minor changes in fat32

move stack after bss padding
some structures for okteta
2025-09-20 08:29:43 -04:00 · 2025-09-18 19:16:27 -04:00 · 2025-09-18 17:20:17 -04:00 · 2025-09-18 14:25:27 -04:00 · 2025-09-18 14:19:39 -04:00 · 2025-09-18 14:07:45 -04:00
40 changed files with 1826 additions and 1027 deletions
--- a/.gitea/workflows/onpush.yaml
+++ b/.gitea/workflows/onpush.yaml
@@ -22,7 +22,7 @@ jobs:
      - name: Ensure image is up to date and install build tools and deps
        run: |
          bash -c "apt update && apt upgrade -y"
-          apt install -y build-essential nasm mount fdisk dosfstools 
+          apt install -y build-essential nasm mtools fdisk dosfstools 

      - name: Build stevia
        run: make
@@ -33,8 +33,8 @@ jobs:
        with:
          name: stevia-${{ github.run_number }}
          path: |
-            build/**
-            disk.img
-            disk.img.gz
+            build/output/artifacts.tar.gz
+            build/output/disk.img.gz
+            build/output/part.img.gz
          if-no-files-found: error
          retention-days: 30   # override server default if you like
--- a/.github/workflows/daily.yaml
+++ b/.github/workflows/daily.yaml
@@ -0,0 +1,35 @@
+name: Daily Build and trunk tester
+on:
+  push:
+    branches: [ $default-branch ]
+  schedule:
+    - cron: "0 7 * * 1"   # mondays at 07:00
+  workflow_dispatch: {}
+
+jobs:
+  debian_update:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout (if needed)
+        uses: actions/checkout@v4
+      
+      - name: Update and install build tools and deps
+        run: |
+          sudo bash -c "apt update && apt upgrade -y"
+          sudo apt install -y build-essential nasm mtools fdisk dosfstools 
+
+      - name: Build stevia
+        run: make
+
+      - name: Upload build artifacts
+        if: always()   # still keep logs/artifacts even if build fails
+        uses: actions/upload-artifact@v4
+        with:
+          name: stevia-${{ github.run_number }}
+          path: |
+            build/output/artifacts.tar.gz
+            build/output/disk.img.gz
+            build/output/part.img.gz
+          if-no-files-found: error
+          retention-days: 7   # override server default if you like
+          
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,5 @@
-out/*
 build/*
+build/output/*
 *.img
 *.img.gz
 *.img.gz
@@ -9,3 +9,6 @@ stevia-log
 .vscode/
 *.map
 compose-dev.yaml
+eth_null-tx.log
+eth_null-txdump.txt
+*.log
--- a/LICENSE.md
+++ b/LICENSE.md
@@ -1,14 +0,0 @@
-Copyright (C) 2025 Elaina Claus
-
-    This program is free software: you can redistribute it and/or modify
-    it under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    This program is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    GNU General Public License for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with this program.  If not, see <https://www.gnu.org/licenses/>.
--- a/140
+++ b/140
@@ -13,74 +13,108 @@
 #     You should have received a copy of the GNU General Public License
 #     along with this program.  If not, see <https://www.gnu.org/licenses/>.

-include := './include'
-
-mbr_source_files := $(wildcard src/mbr/*.nasm)
-vbr_source_files := $(wildcard src/vbr/*.nasm)
-stage2_source_files := $(wildcard src/stage2/*.nasm)
-boottest_source_files := $(wildcard src/miniboot32/*.nasm)
-
-mbr_binary_files := $(patsubst src/mbr/%.nasm, build/%.bin, $(mbr_source_files))
-vbr_binary_files := $(patsubst src/vbr/%.nasm, build/%.bin, $(vbr_source_files))
-stage2_binary_files := $(patsubst src/stage2/%.nasm, build/%.bin, $(stage2_source_files))
-boottest_binary_files := $(patsubst src/miniboot32/%.nasm, build/%.bin, $(boottest_source_files))
-
-build_dir := 'build'
+INCDIR := include
+BUILD_DIR := build
+IMG := $(BUILD_DIR)/disk.img
+IMGZ := $(BUILD_DIR)/disk.img.gz
+DEP_DIR     := $(BUILD_DIR)/deps

 # Get current Git version (tag) and hash
-GIT_VERSION := $(shell git describe --tags)
-GIT_HASH := $(shell git rev-parse HEAD)
+GIT_VERSION := $(shell git describe --tags --always --dirty 2>/dev/null || echo unknown)
+GIT_HASH := $(shell git rev-parse HEAD 2>/dev/null || echo unknown)
 GIT_NASM_DEFINES := -D __GIT_VER__='"$(GIT_VERSION)"' -D __GIT_HASH__='"$(GIT_HASH)"'

-iso := '/tmp/disk.img'
-isoz := 'disk.img.gz'
+NASMFLAGS   := -Wall -f bin -i$(INCDIR)/ $(GIT_NASM_DEFINES)

-qemu_args := -L ./bin/ -bios bios.bin -cpu pentium3 -m 128 -S -s -monitor stdio -nic none
-.PHONY: all mbr vbr stage2 boottest clean run run_bochs iso isoz
+QEMU        ?= qemu-system-i386
+QEMU_ARGS := \
+    -M pc-i440fx-8.2,accel=tcg \
+    -cpu pentium3 \
+    -m 64M \
+    -rtc base=localtime \
+    -boot c \
+    -vga std \
+    -display gtk,gl=off \
+    -device e1000,netdev=n0,mac=52:54:00:12:34:56 \
+    -netdev user,id=n0 \
+    -device piix3-usb-uhci \
+    -parallel null \
+    -serial null -serial none -serial none -serial none \
+    -chardev file,id=dbg,path=bochs-e9.log,append=on \
+    -device isa-debugcon,iobase=0xe9,chardev=dbg \
+    -msg timestamp=on

-all: $(iso) $(isoz) $(mbr_binary_files) $(vbr_binary_files) $(stage2_binary_files)
-mbr: $(mbr_binary_files)
-vbr: $(vbr_binary_files)
-stage2: $(stage2_binary_files)
-boottest: $(boottest_binary_files)
+MBR_SRCS 	  := $(wildcard src/mbr/*.nasm)
+VBR_SRCS 	  := $(wildcard src/vbr/*.nasm)
+STAGE2_SRCS   := $(wildcard src/stage2/*.nasm)
+BOOTTEST_SRCS := $(wildcard src/miniboot32/*.nasm)

-clean:
-	@rm -rvf *.map
-	@rm -rvf $(build_dir)/*
-	@rm -rvf $(iso)
-	@rm -rvf $(isoz)
+MBR_BINS 	  := $(patsubst src/mbr/%.nasm, $(BUILD_DIR)/mbr/%.bin, $(MBR_SRCS))
+VBR_BINS 	  := $(patsubst src/vbr/%.nasm, $(BUILD_DIR)/vbr/%.bin, $(VBR_SRCS))
+STAGE2_BINS   := $(patsubst src/stage2/%.nasm, $(BUILD_DIR)/stage2/%.bin, $(STAGE2_SRCS))
+BOOTTEST_BINS := $(patsubst src/miniboot32/%.nasm, $(BUILD_DIR)/miniboot32/%.bin, $(BOOTTEST_SRCS))

-run: $(iso)
-	@sudo qemu-system-i386 $(qemu_args) -hda $(iso)
+ALL_BINS	  := $(MBR_BINS) $(VBR_BINS) $(STAGE2_BINS) $(BOOTTEST_BINS)

-run_bochs: $(iso)
-	@bochs -q
+.DEFAULT_GOAL := all
+.DELETE_ON_ERROR:

-iso: $(iso)
-	@file $(iso)
+.PHONY: all mbr vbr stage2 boottest clean run run_qemu run_bochs img imgz help
+all: $(IMG) $(IMGZ) $(ALL_BINS)
+mbr: $(MBR_BINS)
+vbr: $(VBR_BINS)
+stage2: $(STAGE2_BINS)
+boottest: $(BOOTTEST_BINS)

-isoz: $(isoz)
-	@file $(isoz)
+# Build Rules

-build/%.bin: src/mbr/%.nasm
-	@mkdir -p $(shell dirname $@)
-	@nasm -i$(include) -Wall -f bin $(GIT_NASM_DEFINES) $< -o $@
+$(BUILD_DIR)/mbr/%.bin: src/mbr/%.nasm | $(DEP_DIR)
+	@mkdir -p $(@D)
+	@nasm $(NASMFLAGS) -MD $(DEP_DIR)/$*.d -MT $@ $< -o $@

-build/%.bin: src/vbr/%.nasm
-	@mkdir -p $(shell dirname $@)
-	@nasm -i$(include) -Wall -f bin $(GIT_NASM_DEFINES) $< -o $@
+$(BUILD_DIR)/vbr/%.bin: src/vbr/%.nasm | $(DEP_DIR)
+	@mkdir -p $(@D)
+	@nasm $(NASMFLAGS) -MD $(DEP_DIR)/$*.d -MT $@ $< -o $@

-build/%.bin: src/stage2/%.nasm
-	@mkdir -p $(shell dirname $@)
-	@nasm -i$(include) -Wall -f bin $(GIT_NASM_DEFINES) $< -o $@
+$(BUILD_DIR)/stage2/%.bin: src/stage2/%.nasm | $(DEP_DIR)
+	@mkdir -p $(@D)
+	@nasm $(NASMFLAGS) -MD $(DEP_DIR)/$*.d -MT $@ $< -o $@

-build/%.bin: src/miniboot32/%.nasm
-	@mkdir -p $(shell dirname $@)
-	@nasm -i$(include) -Wall -f bin $(GIT_NASM_DEFINES) $< -o $@
+$(BUILD_DIR)/miniboot32/%.bin: src/miniboot32/%.nasm | $(DEP_DIR)
+	@mkdir -p $(@D)
+	@nasm $(NASMFLAGS) -MD $(DEP_DIR)/$*.d -MT $@ $< -o $@

-$(iso): $(mbr_binary_files) $(vbr_binary_files) $(stage2_binary_files) $(boottest_binary_files)
-	@echo root access needed to create disk image...
+
+$(DEP_DIR):
+	@mkdir -p $@
+
+# Disk image's
+
+$(IMG): $(ALL_BINS) | scripts/create-disk.sh
 	@scripts/create-disk.sh

-$(isoz): $(iso)
-	@gzip -9kc $(iso) > $(isoz)
+$(IMGZ): $(IMG)
+	@gzip -9kc $(IMG) > $(IMGZ)
+
+img: $(IMG)
+	@file $(IMG)
+
+imgz: $(IMGZ)
+	@file $(IMGZ)
+
+# Helpers
+
+run: $(IMG)
+	@$(QEMU) $(QEMU_ARGS) -drive file=$(IMG),if=ide,index=0,media=disk,format=raw \
+
+run_bochs: $(IMG)
+	@bochs -q
+
+clean:
+	@$(RM) -rv $(BUILD_DIR)/
+
+help:
+	@awk '/^[A-Za-z0-9_%-]+:/{print $$1}' $(MAKEFILE_LIST) | sed 's/:$$//' | sort -u
+
+# Include header deps
+-include $(wildcard $(DEP_DIR)/*.d)
--- a/README.md
+++ b/README.md
@@ -1,6 +1,8 @@
 # Stevia Bootloader

-Stevia is a lightweight, hobby bootloader written in Assembly and C, designed for educational purposes. It targets x86 (Pentium III era) and aims to be simple, approachable, and understandable, focusing on minimalism and core functionality.
+Stevia is a lightweight, hobby bootloader written in Assembly (NASM) and is designed for educational purposes. It targets 686+ and aims to be simple, approachable, and understandable, focusing on minimalism and core functionality.
+
+Please note: **Most development currently takes place in Bochs (and maybe is tested on QEMU), due to this, the code in this repo has not been tested throughly aginist real hardware. As with most projects of this nature, there is a risk of damage due to improper programing of hardware, while careful effort is taken to not break the computer...accidents and mistakes can/do happen.**

 ## Features

@@ -10,18 +12,13 @@ Stevia is a lightweight, hobby bootloader written in Assembly and C, designed fo
 - **Stage 2 Bootloader**: Loads the kernel into memory and passes control.
 - **Basic Filesystem Support**: Initial filesystem recognition (details depend on implemented filesystem support).
 - **Memory Map Parsing**: Detects available memory regions via BIOS interrupts.
- **GDT Initialization**: Sets up the Global Descriptor Table for protected mode.
-
-### In Progress
-
- **Interrupt Descriptor Table (IDT) Setup**: Setting up basic interrupt handling.
- **Basic Keyboard Input**: Initial support for capturing keystrokes.
+- **GDT Initialization**: Sets up the Global Descriptor Table for protected/unreal mode.

 ### Planned Features

- **Task Scheduling**: Basic round-robin task switching.
+- **Interrupt Descriptor Table (IDT) Setup**: Setting up basic interrupt handling.
+- **Basic Keyboard Input**: Initial support for capturing keystrokes.
 - **Filesystem Expansion**: Support for additional filesystems.
- **More Robust Driver Support**: Additional hardware drivers, such as for storage devices.

 ## Installation

@@ -29,42 +26,40 @@ Stevia is a lightweight, hobby bootloader written in Assembly and C, designed fo

 To build and run Stevia, you will need the following tools installed on your system:

- **Assembler**: NASM for assembling bootloader components.
- **C Compiler**: GCC (cross-compiler recommended).
- **Emulator**: Bochs or QEMU for testing.
- **GNU Make**: For building the project.
- **Utilities**:
-  - **dd**: For creating raw disk images.
-  - **losetup** (Linux only): For associating loop devices with disk images.
-  - **sfdisk**: For creating DOS disk partitions.
-  - **mkfs.fat**: For formatting partitions as FAT32.
-  - **hdiutil** (macOS only): For attaching disk images.
-  - **newfs\_msdos** (macOS only): For formatting FAT32 partitions.
+- **Assembler**: NASM for assembling bootloader components, you could use a compatible assembler but YMMV.
+- **GNU make**: For building the project.
+- **mtools**: To access the FAT partition
+- **fdisk**: To create disk images and setup partition tables
+- **dosfstools**: FAT32 creation
+- **an x86 Emulator**: Bochs is the primary dev target, but stevia should run on any x86 emulator/hardware with at least a Pentium 3 and 640KiB of memory.

 ### Building and Running

 1. **Clone the repository**:
+
   ```sh
   git clone https://github.com/Nivirx/stevia.git
   cd stevia
   ```
+
 2. **Build the bootloader and create a bootable disk image**:
+
   ```sh
-   sudo make
+   make
   ```
+
 3. **Run using Bochs**:
+
   ```sh
-   bochs -f bochsrc.txt
+   bochs -q -f bochsrc.txt
   ```

 ## Project Goals

-Stevia is intended to be a learning tool for those interested in low-level programming, focusing on understanding the basics of how a computer starts up and manages early system resources. Contributions and forks are welcome, especially from those interested in expanding the functionality.
+Stevia is intended to be a learning tool for those interested in low-level programming, focusing on understanding the basics of how a computer starts up and manages early system resources.

-## Contributing
-
-We welcome contributions! Feel free to open issues for bugs or feature requests, and submit pull requests for any improvements. Please ensure that your code follows the existing style and includes appropriate comments.
+You are welcome to fork/review the code base but I am generally not accepting PR's/Contributions to the code at this time.

 ## License

-This project is licensed under the MIT License. See the [LICENSE](LICENSE) file for more details.
+This project is licensed under the GPLv3 License. See the [LICENSE](LICENSE.md) or [COPYING](COPYING) file for more details.
--- a/bochsrc.txt
+++ b/bochsrc.txt
@@ -1,44 +1,44 @@
-# configuration file generated by Bochs
-plugin_ctrl: voodoo=false, unmapped=true, biosdev=true, speaker=true, extfpuirq=true, parallel=true, serial=true, busmouse=false, e1000=false, es1370=false, gameport=true, ne2k=false, sb16=false, usb_uhci=false, usb_ohci=false, usb_ehci=false, usb_xhci=false
+#
+# Bochs config
+#
 config_interface: textconfig
-display_library: wx
-memory: guest=64, host=64, block_size=128
-romimage: file="/usr/share/bochs/BIOS-bochs-legacy", address=0x00000000, options=none, flash_data=none
-vgaromimage: file="/usr/share/bochs/VGABIOS-lgpl-latest"
-boot: disk
-floppy_bootsig_check: disabled=0
-floppya: type=1_44
-# no floppyb
-ata0: enabled=true, ioaddr1=0x1f0, ioaddr2=0x3f0, irq=14
-ata0-master: type=disk, path="./disk.img", mode=flat, cylinders=0, heads=0, spt=0, sect_size=512, model="Stevia Disk", biosdetect=auto, translation=lba
-ata0-slave: type=none
-ata1: enabled=false
-ata1-master: type=none
-ata1-slave: type=none
-ata2: enabled=false
-ata3: enabled=false
-optromimage1: file=none
-optromimage2: file=none
-optromimage3: file=none
-optromimage4: file=none
-optramimage1: file=none
-optramimage2: file=none
-optramimage3: file=none
-optramimage4: file=none
-pci: enabled=1, chipset=i440fx, slot1=none, slot2=none, slot3=none, slot4=none, slot5=none
-vga: extension=vbe, update_freq=10, realtime=1, ddc=builtin
-cpu: count=1, ips=1000000, model=p3_katmai, reset_on_triple_fault=1, cpuid_limit_winnt=0, ignore_bad_msrs=1, mwait_is_nop=0
-print_timestamps: enabled=0
-port_e9_hack: enabled=false, all_rings=false
+display_library: x, options=gui_debug
+plugin_ctrl: voodoo=false, unmapped=true, biosdev=true, speaker=true, extfpuirq=true, parallel=true, serial=true, busmouse=false, e1000=true, es1370=false, gameport=true, ne2k=false, sb16=false, usb_uhci=true, usb_ohci=false, usb_ehci=false, usb_xhci=false
+print_timestamps: enabled=1
 private_colormap: enabled=0
-clock: sync=none, time0=local, rtc_sync=0
-# no cmosimage
 log: -
 logprefix: %t%e%d
 debug: action=ignore
 info: action=report
 error: action=report
 panic: action=ask
+magic_break: enabled=1
+port_e9_hack: enabled=1, all_rings=false
+#
+# Machine Spec
+# 1x Pentium 3 @ (1M IPS) w/ 64MiB of System memory on the i440fx
+cpu: count=1, ips=1000000, model=p3_katmai, reset_on_triple_fault=0, cpuid_limit_winnt=0, ignore_bad_msrs=1, mwait_is_nop=0
+memory: guest=64, host=64, block_size=128
+romimage: file="/usr/share/bochs/BIOS-bochs-legacy", address=0x00000000, options=none, flash_data=none
+vgaromimage: file="/usr/share/vgabios/vgabios-stdvga.bin"
+pci: enabled=1, chipset=i440fx
+vga: extension=vbe, update_freq=10, realtime=1, ddc=builtin
+clock: sync=none, time0=local, rtc_sync=0
+#
+# Disks
+#
+boot: disk
+floppy_bootsig_check: disabled=0
+floppya: type=1_44
+floppyb: type=1_44
+ata0: enabled=true, ioaddr1=0x1f0, ioaddr2=0x3f0, irq=14
+ata0-master: type=disk, path="./build/disk.img", mode=flat, cylinders=0, heads=0, spt=0, sect_size=512, model="Stevia Disk", biosdetect=auto, translation=lba
+ata0-slave: type=none
+#
+# Other hardware
+#
+usb_ehci: enabled=1, companion=ohci
+e1000: enabled=1, mac=52:54:00:12:34:56, ethmod=null
 keyboard: type=mf, serial_delay=150, paste_delay=100000, user_shortcut=none
 mouse: type=none, enabled=false, toggle=ctrl+mbutton
 sound: waveoutdrv=dummy, waveout=none, waveindrv=dummy, wavein=none, midioutdrv=dummy, midiout=none
@@ -49,5 +49,3 @@ com1: enabled=true, mode=null
 com2: enabled=false
 com3: enabled=false
 com4: enabled=false
-magic_break: enabled=1
-port_e9_hack: enabled=1, all_rings=false
--- a/docs/Stevia
+++ b/docs/Stevia
@@ -207,24 +207,45 @@ Each GDT entry is 8 bytes:

 ## **5. Memory Layout Example**

-### **Low Memory (First MiB)**
+### **Low Memory/Upper Memory map (<= 1MiB)**

 | Start       | End         | Size            | Type                 | Description                    |
-|-------------|-------------|-----------------|-----------------------|----------------------------------|
-| 0x00000000  | 0x000003FF  | 1 KiB           | RAM (partially unusable) | Real Mode IVT (Interrupt Vector Table) |
-| 0x00000400  | 0x000004FF  | 256 bytes       | RAM (partially unusable) | BDA (BIOS data area)             |
-| 0x00000500  | 0x00007BFF  | almost 30 KiB   | RAM - free for use     | Conventional memory              |
-| 0x00007C00  | 0x00007DFF  | 512 bytes       | RAM (partially unusable) | OS BootSector                    |
-| 0x00007E00  | 0x0007FFFF  | 480.5 KiB       | RAM - free for use     | Conventional memory              |
-| 0x00080000  | 0x0009FFFF  | 128 KiB         | RAM (partially unusable) | EBDA (Extended BIOS Data Area)   |
-| 0x000A0000  | 0x000FFFFF  | 384 KiB         | various (unusable)     | Video memory, ROM Area           |
+|-------------|-------------|-----------------|----------------------|--------------------------------|
+| 0x00000000  | 0x000003FF  | 1 KiB           | RAM reclaimable~1~   | Real Mode IVT                  |
+| 0x00000400  | 0x000004FF  | 256 bytes       | RAM reclaimable~1~   | BDA                            |
+| 0x00000500  | 0x00007BFF  | 29 KiB + 767b   | RAM - free           | Conventional memory            |
+| 0x00007C00  | 0x00007DFF  | 512 bytes       | RAM reclaimable~2~   | OS BootSector                  |
+| 0x00007E00  | 0x0007FFFF  | 480.5 KiB       | RAM - free           | Conventional memory            |
+| 0x00080000  | 0x0009FFFF  | 128 KiB         | RAM (unusable)~1~    | EBDA (Extended BIOS Data Area) |
+| 0x000A0000  | 0x000FFFFF  | 384 KiB         | Upper RAM (unusable) | Video memory, ROM Area         |

-### **Extended Memory (Above 1 MiB)**
+1. Reclaimable in the event that you *never* need the BIOS again & once the CPU is in protected mode.
+2. Reclaimable after you are done with with the MBR/VBR stages.
+
+### **Extended Memory (> 1 MiB)**
+
+This is only an example, you should always check the memory map.

 | Start       | End         | Size            | Description                           |
-|-------------|-------------|-----------------|------------------------|
-| 0x00100000  | 0x00EFFFFF  | 14 MiB          | RAM - free for use     |
+|-------------|-------------|-----------------|---------------------------------------|
+| 0x00100000  | 0x00EFFFFF  | 14 MiB          | RAM(?) - free for use                    |
 | 0x00F00000  | 0x00FFFFFF  | 1 MiB           | Possible memory-mapped hardware (ISA) |
 | 0x01000000  | ?           | ?               | More extended memory                  |
 | 0xC0000000  | 0xFFFFFFFF  | 1 GiB           | Memory mapped PCI devices, BIOS, etc. |
-| 0x0000000100000000 | ?     | ?               | RAM - usable in PAE/64-bit mode |
+| 0x0000000100000000 | ?    | ?               | RAM(?) - usable in PAE/64-bit mode      |
+
+
+## **6. Stage2 Memory Layout  **
+
+Overall, Tiny (64 KiB page) Code/Data, Flat 4GiB mapping in gs/fs after unreal switch
+
+| Start       | End         | Size (Bytes) | Type               | Description                |
+|-------------|-------------|--------------|--------------------|----------------------------|
+| 0x00000000  | 0x000003FF  | 0x400        | RAM - (BIOS)       | Real Mode IVT              |
+| 0x00000400  | 0x000004FF  | 0x100        | RAM - (BIOS)       | BDA                        |
+| 0x00000500  | 0x000042FF  | 0x3E00       | RAM - .text/.data  | Code and constants/strings |
+| 0x00004300  | 0x000044FF  | 0x100        | RAM - .sign        | EOF marker/signature       |
+| 0x00004500  | 0x000074FF  | 0x3000       | RAM - bss          | Runtime data/stack         |
+| 0x00007500  | 0x00007FFF  | 0xB00        | RAM - reserved     | Reserved                   |
+| 0x00008000  | 0x0000DFFF  | 0x6000       | RAM - heap         | Conventional memory        |
+| 0x0000F000  | 0x0000FFFF  | 0x1000       | RAM - reserved     | Reserved                   |
--- a/docs/debug/8086_gdb/.gdbinit
+++ b/docs/debug/8086_gdb/.gdbinit
--- a/docs/debug/8086_gdb/target.xml
+++ b/docs/debug/8086_gdb/target.xml
--- a/docs/debug/x86_ddd/.gdbinit
+++ b/docs/debug/x86_ddd/.gdbinit
--- a/docs/debug/x86_gdb/.gdbinit
+++ b/docs/debug/x86_gdb/.gdbinit
--- a/docs/okteta/structures/mbr/main.osd
+++ b/docs/okteta/structures/mbr/main.osd
@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<data>
+  <struct name="MBR">
+    <!-- 446 bytes: bootstrap code -->
+    <array name="bootCode" length="446">
+      <primitive type="UInt8"/>
+    </array>
+
+    <!-- 4 x 16-byte partition entries -->
+    <array name="partitions" length="4">
+      <struct name="PartitionEntry">
+        <primitive name="status" type="UInt8"/>         <!-- 0x80=bootable -->
+        <array name="chsFirst" length="3"><primitive type="UInt8"/></array>
+        <primitive name="type" type="UInt8"/>
+        <array name="chsLast" length="3"><primitive type="UInt8"/></array>
+        <primitive name="lbaStart" type="UInt32"/>
+        <primitive name="lbaSectors" type="UInt32"/>
+      </struct>
+    </array>
+
+    <!-- Signature 0x55AA (little-endian UInt16 == 0xAA55 on disk) -->
+    <primitive name="signature" type="UInt16"/>
+  </struct>
+</data>
--- a/docs/okteta/structures/mbr/metadata.desktop
+++ b/docs/okteta/structures/mbr/metadata.desktop
@@ -0,0 +1,12 @@
+[Desktop Entry]
+Icon=application-x-executable
+Type=Service
+ServiceTypes=KPluginInfo
+Name=Stevia MBR Structure
+X-KDE-PluginInfo-Author=Elaina Claus
+X-KDE-PluginInfo-Name=mbr
+X-KDE-PluginInfo-Version=1.0
+X-KDE-PluginInfo-Website=https://chtm.me
+X-KDE-PluginInfo-Category=structure
+X-KDE-PluginInfo-License=MIT
+X-KDE-PluginInfo-EnabledByDefault=false
--- a/docs/okteta/structures/vbr/main.osd
+++ b/docs/okteta/structures/vbr/main.osd
@@ -0,0 +1,57 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<data>
+  <struct name="VBR">
+    <!-- 3 bytes: jmp over bpb code -->
+    <array name="jmpcode" length="3">
+      <primitive name="opcode" type="UInt8"/>
+    </array>
+
+    <array name="bs_ident" length="8">
+      <primitive type="Char"/>
+    </array>
+
+    <struct name="FAT32_bpb">
+      <primitive name="BytesPerSector" type="UInt16"/>
+      <primitive name="SectorsPerCluster" type="UInt8"/>
+      <primitive name="ReservedSectors" type="UInt16"/>
+      <primitive name="FatCount" type="UInt8"/>
+      <primitive name="RootEntryCount16" type="UInt16"/>
+      <primitive name="TotalSectors16" type="UInt16"/>
+      <primitive name="MediaDesc" type="UInt8"/>
+      <primitive name="FATSize16" type="UInt16"/>
+      <primitive name="SectorsPerTrack" type="UInt16"/>
+      <primitive name="HeadCount" type="UInt16"/>
+      <primitive name="HiddenSectors" type="UInt32"/>
+      <primitive name="TotalSectors32" type="UInt32"/>
+    </struct>
+
+    <struct name="FAT32_ebpb">
+      <primitive name="FATSize32" type="UInt32"/>
+      <primitive name="ExtFlags" type="UInt16"/>
+      <primitive name="FSVersion" type="UInt16"/>
+      <primitive name="RootDirCluster" type="UInt32"/>
+      <primitive name="FSInfoSector" type="UInt16"/>
+      <primitive name="BkBootSector" type="UInt16"/>
+      <array name="reserved0" length="12">
+        <primitive type="uint8"/>
+      </array>
+      <primitive name="DriveNumber" type="UInt8"/>
+      <primitive name="NtFlags" type="UInt8"/>
+      <primitive name="Signature" type="UInt8"/>
+      <primitive name="VolumeId" type="UInt32"/>
+      <array name="VolumeLabel" length="11">
+        <primitive type="Char"/>
+      </array>
+      <array name="FilesystemIdent" length="8">
+        <primitive type="Char"/>
+      </array>
+    </struct>
+
+    <array name="BootCode" length="420">
+      <primitive type="UInt8"/>
+    </array>
+
+    <!-- Signature 0xAA55 -->
+    <primitive name="signature" type="UInt16"/>
+  </struct>
+</data>
--- a/docs/okteta/structures/vbr/metadata.desktop
+++ b/docs/okteta/structures/vbr/metadata.desktop
@@ -0,0 +1,12 @@
+[Desktop Entry]
+Icon=application-x-executable
+Type=Service
+ServiceTypes=KPluginInfo
+Name=Stevia FAT32 VBR Structure
+X-KDE-PluginInfo-Author=Elaina Claus
+X-KDE-PluginInfo-Name=vbr32
+X-KDE-PluginInfo-Version=1.0
+X-KDE-PluginInfo-Website=https://chtm.me
+X-KDE-PluginInfo-Category=structure
+X-KDE-PluginInfo-License=MIT
+X-KDE-PluginInfo-EnabledByDefault=false
--- a/include/BIOS/func/E820_memory_map.nasm
+++ b/include/BIOS/func/E820_memory_map.nasm
@@ -33,30 +33,27 @@ struc AddressRangeDescStruct_t
    .ExtType        resd 1
 endstruc

+; !!! this procedure changes ES !!!
 ALIGN 4, db 0x90
 GetMemoryMap:
-    __CDECL16_ENTRY
+    __CDECL16_PROC_ENTRY
    push es         ; save segment register
 .func:
-    mov dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries], 0
+    mov word [SteviaInfo + SteviaInfoStruct_t.u16_E820MMapEntryCount], 0
    
-    mov eax, 0xE820                         ; select 0xE820 function
    xor ebx, ebx                            ; Continuation value, 0 for the first call
-
-    lea dx, [BIOSMemoryMap]
-    shr dx, 4
-    mov es, dx
-    xor di, di                              ; (BIOSMemoryMap >> 4):0 makes di an index into BIOSMemoryMap
-
-    mov ecx, AddressRangeDescStruct_t_size
-    mov edx, 0x534D4150                     ; 'SMAP' magic
+    mov di, BIOSMemoryMap                   ; destination is es:di, es should == ds
+    mov ecx, AddressRangeDescStruct_t_size  ; hard request ACPI 3.0 table versions (24 bytes)
 .loop_L1:
-    int 0x15
+    mov eax, 0x0000E820                     ; select 0xE820 function
+    mov edx, 0x534D4150                     ; 'SMAP' magic
+    clc                                     ; clear carry
+    int 0x15                                ; data will be stored at es:di by e820 call
    jc GetMemoryMap.error
    cmp eax, 0x534D4150
    jne GetMemoryMap.no_smap_returned
 .no_error:
-    inc dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries]
+    inc word [SteviaInfo + SteviaInfoStruct_t.u16_E820MMapEntryCount]

    cmp ecx, 20                             ; TODO: maybe this could be handled better than just panicing
    jb GetMemoryMap.nonstandard_e820        ; non-standard entry found 
@@ -64,9 +61,11 @@ GetMemoryMap:
    cmp ebx, 0
    je GetMemoryMap.endp                    ; 0 in ebx means we have reached the end of memory ranges

-    add di, AddressRangeDescStruct_t_size   ; increment di to next descriptor
-    mov edx, eax                            ; 'SMAP' to edx
-    mov eax, 0xE820                         ; select E820 function
+    ; setup for next loop, ebx is our next index and has already been set.
+    xor ecx, ecx
+    mov ecx, AddressRangeDescStruct_t_size  ; set ecx (requested_size) to 24 bytes
+    add di, cx                              ; increment di to next descriptor so es:di points to the next free space
+
    jmp GetMemoryMap.loop_L1
 .error:
    ERROR STAGE2_MM_E820_MISC_ERR
@@ -76,8 +75,40 @@ GetMemoryMap:
    ERROR STAGE2_MM_E820_NO_SMAP
 .endp:
    pop es
-    __CDECL16_EXIT
+    __CDECL16_PROC_EXIT
    ret

+PrintMemoryMap:
+    __CDECL16_PROC_ENTRY
+.func:
+    mov eax, dword [SteviaInfo + SteviaInfoStruct_t.u16_E820MMapEntryCount]
+    cmp eax, 0
+    je PrintMemoryMap.endp          ; if entries == 0, exit
+
+    mov ecx, eax                    ; store # of entries in counter
+    mov eax, BIOSMemoryMap          ; address to start of e820 mmap
+
+    push dword ecx
+    push dword eax
+    call FormatMemoryMapEntry
+    add sp, 0x8
+
+    ; ax contains segment offset to string after call
+    ; TODO: going to need an allocator for strings and stuff...
+    ; print_string strformat_buffer
+    
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+
+FormatMemoryMapEntry:
+    __CDECL16_PROC_ENTRY
+.func:
+    ; create a string buffer somewhere and return address to result string in ax
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+
+
 %endif
 %define __INC_E820MEMORY_MAP
--- a/include/BIOS/func/a20enable.nasm
+++ b/include/BIOS/func/a20enable.nasm
@@ -64,7 +64,7 @@
 ;    Bits 6-7 - 00: HDD activity LED off; any other value is "on"
 ALIGN 4, db 0x90
 EnableA20:
-    __CDECL16_ENTRY
+    __CDECL16_PROC_ENTRY
    push ds
    push es
 .a20_check:
@@ -105,6 +105,7 @@ EnableA20:
    je EnableA20.endp         ; A20 is already enabled

    mov ax, 0x2403
+    clc                             ; clear carry
    int 0x15
    jc EnableA20.do_fallback_a20    ; carry = error...not supported?
    cmp ah, 0
@@ -121,6 +122,7 @@ EnableA20:
    ERROR STAGE2_A20_FAILED
 .do_bios_a20:
    mov ax, 0x2401
+    clc                             ; clear carry
    int 0x15
    jmp EnableA20.a20_check
 .do_fast_a20:
@@ -132,7 +134,7 @@ EnableA20:
 .endp:
    pop es
    pop ds
-    __CDECL16_EXIT
+    __CDECL16_PROC_EXIT
    ret
    
 %endif
--- a/include/BIOS/func/ext_read.nasm
+++ b/include/BIOS/func/ext_read.nasm
@@ -31,29 +31,6 @@ struc LBAPkt_t
    .lower_lba   resd 1
    .upper_lba   resd 1
 endstruc
-; call_read_disk_raw <word segment> <word offset> <dword lba> <word count> <word drive_num>
-%macro call_read_disk_raw 5
-    movzx ax, %5
-    push ax                                            ; drive_num
-
-    movzx ax, %4
-    push ax                                            ; count
-
-    movzx dword eax, %3
-    push dword eax                                     ; lba
-
-    movzx ax, %2
-    push ax                                            ; offset
-
-    movzx ax, %1
-    push ax                                            ; segment = 0
-
-    ; uint8_t read_stage2_raw(uint16_t buf_segment, uint16_t buf_offset, 
-    ;                         uint32_t lba,
-    ;                         uint16_t count, uint16_t drive_num)
-    call read_disk_raw
-    add sp, 0xC
-%endmacro

 ; Wrapper for AH=0x42 INT13h (Extended Read)
 ;
@@ -70,21 +47,17 @@ endstruc
 ; disk address packet's block count field set to number of blocks
 ; successfully transferred
 ;
-;
 ; uint8_t read_stage2_raw(uint16_t buf_segment, uint16_t buf_offset, 
 ;                         uint32_t lba,
 ;                         uint16_t count, uint8_t drive_num)
 ALIGN 4, db 0x90
-read_disk_raw:
-    __CDECL16_ENTRY
+BIOS_int13h_ext_read:
+    __CDECL16_PROC_ENTRY
 .func:                         
-    mov ax, LBAPkt_t_size
-    push ax                 ; len
-    xor ax, ax
-    push ax                 ; val = 0
-    mov ax, lba_packet
-    push ax                 ; dest = lba_packet address
-    call kmemset        
+    push LBAPkt_t_size        ; len
+    push 0x00                 ; val = 0
+    push lba_packet           ; dest = lba_packet address
+    call kmemset              ; kmemset(dst, val, len)
    add sp, 0x06

    mov bx, lba_packet
@@ -97,7 +70,8 @@ read_disk_raw:
    mov dword [bx + LBAPkt_t.lower_lba], eax

    ; upper_lba is zero from kmemset
-    ; TODO: possiblly support >32bit LBA addresses in the future, this limits us to 4GiB
+    ; TODO: possiblly support >32bit LBA addresses in the future
+    ; this will limit us to (4GiB * sector size) of readable lba's from the disk

    mov ax, [bp + 6]
    mov word [bx + LBAPkt_t.offset], ax
@@ -111,6 +85,7 @@ read_disk_raw:
    mov ah, 0x42                ; call #
    mov dl, byte [bp + 14]      ; drive #             

+    clc                         ; clear carry
    int 0x13
    jnc .endf

@@ -119,10 +94,10 @@ read_disk_raw:
    %elifdef __STEVIA_VBR
    ERROR VBR_ERROR_DISK_READ_ERR
    %else
-    ERROR STAGE2_MBR_DISK_READ_ERROR
+    ERROR STAGE2_INT13_DISK_READ_ERR
    %endif
 .endf:
-    __CDECL16_EXIT
+    __CDECL16_PROC_EXIT
    ret

 %endif
--- a/include/BIOS/func/video.nasm
+++ b/include/BIOS/func/video.nasm
@@ -20,25 +20,27 @@
 ALIGN 4, db 0x90
 SetTextMode:
 .prolog:
-    __CDECL16_ENTRY
+    __CDECL16_PROC_ENTRY
    pushf
 .func:
    xor ah, ah                  ; Set Video mode BIOS function
-    mov al, 0x02                ; 16 color 80x25 Text mode
+    mov al, 0x03                ; 16 color 80x25 Text mode
    int 0x10                    ; Call video interrupt
                                
+
    mov ah, 0x05                ; Select active display page BIOS function
    xor al, al                  ; page 0
    int 0x10                    ; call video interrupt
 .endp:
    popf
-    __CDECL16_EXIT
+    __CDECL16_PROC_EXIT
    ret

-; disables blinking text mode cursor
+; disables blinking text mode cursor via crtc pokes
+; 0x3D4/0x3D5 for color, mono at 0x3B4/0x3B5
 ALIGN 4, db 0x90
-disable_cursor:
-    __CDECL16_ENTRY
+disable_cursor_crtc:
+    __CDECL16_PROC_ENTRY
 .func:
    mov dx, 0x3D4
 	mov al, 0xA	    ; low cursor shape register
@@ -48,8 +50,126 @@ disable_cursor:
 	mov al, 0x20	; bits 6-7 unused, bit 5 disables the cursor, bits 0-4 control the cursor shape
 	out dx, al
 .endp:
-    __CDECL16_EXIT
+    __CDECL16_PROC_EXIT
    ret

+; disables blinking text mode cursor via BIOS int 10h, ah = 01
+ALIGN 4, db 0x90
+disable_cursor_bios:
+    __CDECL16_PROC_ENTRY
+.func:
+    push bx
+    mov  ah, 03h      ; read cursor pos & shape
+    xor  bh, bh
+    int  10h          ; CH=top scanline, CL=bottom
+
+    or   ch, 20h      ; set bit 5 = disable
+    mov  ah, 01h      ; set leaf 01h
+    int  10h
+    pop  bx
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+
+; Prints a C-Style string (null terminated) using BIOS vga teletype call
+; void PrintString(char* buf)
+ALIGN 4, db 0x90
+PrintString:
+    __CDECL16_PROC_ENTRY
+    mov di, [bp + 4]    ; first arg is char[] 
+.str_len:
+    xor cx, cx         ; ECX = 0
+    not cx             ; ECX = -1 == 0xFFFF
+    xor ax, ax         ; search for al = 0x0
+
+    cld
+    repne scasb        ; deincrement cx while searching for al
+
+    not cx             ; the inverse of a neg number = abs(x) - 1
+    dec cx             ; CX contains the length of the string - nul byte at end
+.print:
+    mov si, [bp + 4]            ; source string
+.print_L0:
+    movzx ax, byte [si]
+    %ifdef __STEVIA_DEV_DEBUG
+    out 0xe9, byte al           ; bochs magic debug port
+    %endif
+    push ax
+    call PrintCharacter
+    add sp, 0x2
+
+    inc si
+    dec cx
+
+    jcxz PrintString.endp
+    jmp PrintString.print_L0    ; Fetch next character from string
+.endp:
+    __CDECL16_PROC_EXIT
+    ret                         ; Return from procedure
+
+; Prints a single character
+; void PrintCharacter(char c);
+ALIGN 4, db 0x90
+PrintCharacter:
+    __CDECL16_PROC_ENTRY
+.func:
+    mov al, byte [bp + 4]       ; AL = character c
+    mov ah, 0x0E                ; INT 0x10, AH=0x0E call
+    mov bx, 0x0007              ; BH = page no. BL =Text attribute
+    int 0x10                    ; call video interrupt
+                                ; TODO: check for carry and clear carry before call
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+
+; TODO: fix the prolog, epilog and stack usage to confirm with cdecl16
+; prints the hex representation of of val
+; void PrintDWORD(uint32_t val);
+ALIGN 4, db 0x90
+PrintDWORD:
+    __CDECL16_PROC_ENTRY
+.func: 
+    mov si, IntToHex_table
+    mov ebx, 16     ; base-16
+
+    mov eax, dword [bp + 4]     ;val
+
+    xor edx, edx
+    xor cx, cx
+.next_digit:
+    div ebx            ; dividend in edx:eax -> quotient in eax, remainder in edx
+    push dx            ; save remainder
+    inc cx
+
+    xor dx, dx
+    test eax, eax
+    jnz PrintDWORD.next_digit
+
+.zero_pad:
+    cmp cx, 0x0008
+    je PrintDWORD.print_stack
+    xor ax, ax
+    push ax
+    inc cx
+    jmp PrintDWORD.zero_pad
+
+.print_stack:
+    pop bx
+    dec cx
+    push cx
+
+    movzx ax, byte [bx+si+0]    ; bx = index into Hex lookup table
+    push ax
+    call PrintCharacter
+    add sp, 0x2
+
+    pop cx
+
+    jcxz PrintDWORD.endp
+    jmp PrintDWORD.print_stack
+
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
 %endif
 %define __INC_VIDEO
--- a/include/cdecl16.inc
+++ b/include/cdecl16.inc
@@ -13,20 +13,23 @@
 ;     You should have received a copy of the GNU General Public License
 ;     along with this program.  If not, see <https://www.gnu.org/licenses/>.

-%ifnmacro __CDECL16_ENTRY
-%macro __CDECL16_ENTRY 0
+%ifnmacro __CDECL16_PROC_ENTRY
+%macro __CDECL16_PROC_ENTRY 0-1
    push bp
    mov bp, sp
-    sub sp, 0x10

    push si
    push di
    push bx
+
+    %if %0 = 1
+    sub  sp, %1        ; reserve locals only when needed
+    %endif
 %endmacro
 %endif

-%ifnmacro __CDECL16_EXIT
-%macro __CDECL16_EXIT 0
+%ifnmacro __CDECL16_PROC_EXIT
+%macro __CDECL16_PROC_EXIT 0
    pop bx
    pop di
    pop si
@@ -36,29 +39,108 @@
 %endmacro
 %endif

-%ifnmacro __CDECL16_CALLER_SAVE
-%macro __CDECL16_CALLER_SAVE 0
-    push ax
-    push cx
-    push dx
+; __CDECL16_PROC_ARGS nargs
+;   Creates %$arg1 .. %$argN as [bp+4], [bp+6], ...
+;   for use inside of function bodies
+; BUG: still needs to be tested
+%ifnmacro __CDECL16_PROC_ARGS
+%macro __CDECL16_PROC_ARGS 1
+    %push __CDECL16_PROC_ARGS
+    %assign %$__i 1
+    %rep %1
+        %xdefine %$arg%$__i  [bp + 4 + 2*(%$__i-1)]
+        %assign  %$__i %$__i + 1
+    %endrep
+    %pop
 %endmacro
 %endif

-%ifnmacro __CDECL16_CALLER_RESTORE
-%macro __CDECL16_CALLER_RESTORE 0
-    pop dx
-    pop cx
-    pop ax
+; __CDECL16_CALL_ARGS a,b,c  ==> push c / push b / push a
+;   handles pushing values to the stack in the correct order
+%ifnmacro __CDECL16_CALL_ARGS
+%macro __CDECL16_CALL_ARGS 1-*
+    %rep %0
+        %rotate -1      ; move the last argument into %1
+        push %1         ; push last, then next-to-last, ...
+    %endrep
 %endmacro
 %endif

+; __CDECL16_CALL func, nargs   ; adds sp by nargs*2 after call
+;   adds up word pushes to restore stack frame
+;   WARNING: if you push a dword it will only count 2, use __CDECL16_CALL_ARGS_SIZED
+%ifnmacro __CDECL16_CALL
+%macro __CDECL16_CALL 2
+    call %1
+    add  sp, %2*2
+%endmacro
+%endif
+
+; __CDECL16_CALL_ARGS_SIZED func, size1[, size2 ...]  ; sizes in BYTES
+;   if you *need* to pass dword sized args in 16-bit mode, use this to properly
+;   count the stack frame to restore later!
+; BUG: still needs to be tested
+%ifnmacro __CDECL16_CALL_ARGS_SIZED
+%macro __CDECL16_CALL_ARGS_SIZED 2-*
+    %push __CDECL16_CALL_ARGS_SIZED
+    call %1
+    %assign %$__sum 0
+    %assign %$__i 2
+    %rep %0-1
+        %assign %$__sum %$__sum + %[%$__i]   ; sizes may be expressions
+        %assign %$__i %$__i + 1
+    %endrep
+    %if %$__sum & 1
+        %error "__CDECL16_CALL_ARGS_SIZED: total size is odd; pushes must sum to whole bytes actually pushed (usually even)."
+    %endif
+    add sp, %$__sum
+    %pop
+%endmacro
+%endif
+
+%ifnmacro __CDECL16_CLOB
+; Save registers in the order listed. Supports "flags" as a pseudo-reg.
+%macro __CDECL16_CLOB 1-*
+    %rep %0
+        %ifidni %1, flags
+            pushf
+        %else
+            push %1
+        %endif
+        %rotate 1
+    %endrep
+%endmacro
+%endif
+
+%ifnmacro __CDECL16_UNCLOB
+; Restore in reverse order of CLOB. Supports "flags".
+%macro __CDECL16_UNCLOB 1-*
+    %rep %0
+        %rotate -1
+        %ifidni %1, flags
+            popf
+        %else
+            pop %1
+        %endif
+    %endrep
+%endmacro
+%endif
+
+;
+; Only setup the minimum stack frame
+; unlike the above, everything is caller save
+;
 %ifnmacro __FASTCALL16_ENTRY
-%macro __FASTCALL16_ENTRY 0
+%macro __FASTCALL16_ENTRY 0-1
    push bp
    mov bp, sp
+    %if %0 = 1
+    sub  sp, %1        ; reserve locals only when needed
+    %endif
 %endmacro
 %endif

+; restore minimum stack frame, all regs are caller save
 %ifnmacro __FASTCALL16_EXIT
 %macro __FASTCALL16_EXIT 0
    mov sp, bp
--- a/include/config.inc
+++ b/include/config.inc
@@ -15,7 +15,7 @@

 %ifndef __INC_STEVIA_CONFIG

-%define SECTOR_SIZE             512
+%define SECTOR_SIZE            0x200
 %define STAGE2_SECTOR_COUNT    0x20
 ; 16 KiB
 %define MAX_STAGE2_BYTES      (SECTOR_SIZE * STAGE2_SECTOR_COUNT)
--- a/include/early_mem.inc
+++ b/include/early_mem.inc
@@ -1,28 +0,0 @@
-; Copyright (C) 2025 Elaina Claus
-; 
-;     This program is free software: you can redistribute it and/or modify
-;     it under the terms of the GNU General Public License as published by
-;     the Free Software Foundation, either version 3 of the License, or
-;     (at your option) any later version.
-; 
-;     This program is distributed in the hope that it will be useful,
-;     but WITHOUT ANY WARRANTY; without even the implied warranty of
-;     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-;     GNU General Public License for more details.
-; 
-;     You should have received a copy of the GNU General Public License
-;     along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-%ifndef __INC_EARLY_MEM
-
-;PhysicalAddress = Segment * 16 + Offset
-%define SEG_TO_LINEAR(s,o) ((s << 4) + o)
-
-; Offset = physical / (Segment * 16)
-%define LINEAR_TO_OFFSET(p,s) ((p / (s << 4)))
-
-; Seg = (physical - offset) / 16
-%define LINEAR_TO_SEGMENT(p,o) ((p - o) >> 4)
-
-%endif
-%define __INC_EARLY_MEM
--- a/include/entry.inc
+++ b/include/entry.inc
@@ -15,7 +15,7 @@

 %ifndef __INC_ENTRY

-%define MBR_ENTRY                    0x8C00
+%define MBR_ENTRY                    0x6C00
 %define VBR_ENTRY                    0x7C00
 %define STAGE2_ENTRY                 0x0500

--- a/include/error_codes.inc
+++ b/include/error_codes.inc
@@ -15,8 +15,7 @@

 %ifndef __INC_ERROR_CODES

-; Errors
-; 12 Errors, 5 in use
+; MBR Error codes
 %define MBR_ERROR_DISK_T_ERR         'a'
 %define MBR_ERROR_NO_INT32E          'b'
 %define MBR_ERROR_NO_NO_BOOT_PART    'c'
@@ -30,7 +29,7 @@
 %define MBR_ERROR_RESERVED_k         'k'
 %define MBR_ERROR_INT13h_EREAD_ERR   'l'

-; 12 Error
+; VBR Error codes
 %define VBR_ERROR_WRONG_FAT_SIZE     'm'
 %define VBR_ERROR_NO_SIGNATURE       'n'
 %define VBR_ERROR_DISK_READ_ERR      'o'
@@ -44,31 +43,31 @@
 %define VBR_ERROR_RESERVED_w         'w'
 %define VBR_ERROR_RESERVED_x         'x'

-; 22 errors, 8 in use
+; Stage2 Error codes
 %define STAGE2_A20_FAILED            'A'
 %define STAGE2_SIGNATURE_MISSING     'B'
 %define STAGE2_MM_E820_NO_SUPPORT    'C'
 %define STAGE2_MM_E820_MISC_ERR      'D'
 %define STAGE2_MM_E820_NONSTANDARD   'E'
 %define STAGE2_MM_E820_NO_SMAP       'F'
-%define STAGE2_MBR_DISK_READ_ERROR   'G'
-%define STAGE2_FAT32_INIT_ERROR      'H'
-%define STAGE2_FAT32_NO_FILE         'I'
-%define STAGE2_FAT32_END_OF_CHAIN    'J'
-%define STAGE2_FAT32_NCLUS_CFDIVZ    'K'
-%define STAGE2_FAT32_CLS2LBA_CF      'L'
-%define STAGE2_FAT32_INIT_CF         'M'
-%define STAGE2_ERROR_INFOPRINTER     'N'
-%define STAGE2_ERROR_RESERVED_O      'O'
-%define STAGE2_ERROR_RESERVED_P      'P'
-%define STAGE2_ERROR_RESERVED_Q      'Q'
-%define STAGE2_ERROR_RESERVED_R      'R'
-%define STAGE2_ERROR_RESERVED_S      'S'
-%define STAGE2_ERROR_RESERVED_T      'T'
-%define STAGE2_ERROR_RESERVED_U      'U'
-%define STAGE2_ERROR_RESERVED_V      'V'
+%define STAGE2_INT13_DISK_READ_ERR   'G'
+%define STAGE2_FAT32_E_FMT           'H'
+%define STAGE2_FAT32_E_RANGE         'I'
+%define STAGE2_FAT32_E_NOSUCH        'J'
+%define STAGE2_FAT32_E_ISDIR         'K'
+%define STAGE2_FAT32_E_TOOLONG       'L'
+%define STAGE2_FAT32_E_UNSUPPORTED   'M'
+%define STAGE2_FAT32_E_UNIMPLEMENTED 'N'
+%define STAGE2_ERROR_BAD_MBR         'O'
+%define STAGE2_VBR_E_ACTIVE          'P'
+%define STAGE2_VBR_E_SIGN            'Q'
+%define STAGE2_VBR_E_TOT             'R'
+%define STAGE2_VBR_E_FATSZ           'S'
+%define STAGE2_VBR_E_DIRENT          'T'
+%define STAGE2_VBR_E_PARTTYPE        'U'
+%define STAGE2_RESERVED_E_V          'V'

-; for development only, specific errors should be above.
+; Debug error codes
 %define STEVIA_DEBUG_OK              'W'
 %define STEVIA_DEBUG_ERR             'X'
 %define STEVIA_DEBUG_UNIMPLEMENTED   'Y'
--- a/include/fat32/FAT32_SYS.nasm
+++ b/include/fat32/FAT32_SYS.nasm
@@ -0,0 +1,290 @@
+; Copyright (C) 2025 Elaina Claus
+; 
+;     This program is free software: you can redistribute it and/or modify
+;     it under the terms of the GNU General Public License as published by
+;     the Free Software Foundation, either version 3 of the License, or
+;     (at your option) any later version.
+; 
+;     This program is distributed in the hope that it will be useful,
+;     but WITHOUT ANY WARRANTY; without even the implied warranty of
+;     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;     GNU General Public License for more details.
+; 
+;     You should have received a copy of the GNU General Public License
+;     along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+%ifndef __INC_FAT32_SYS
+
+%include "partition_table.inc"
+%include "fat32/fat32_structures.inc"
+
+; int read_mbr(int boot_drive, void* dst)
+; destination buffer needs 512 bytes of space
+FAT32_load_mbr:
+    __CDECL16_PROC_ENTRY
+.proc:
+    ; read mbr on boot drive to memory (for the partition table)
+    movzx ax, byte [bp + 4]
+    push ax                                 ; drive_num (2)
+    push 0x01                               ; count (2)
+
+    push dword 0x0                          ; lba (4)
+
+    push word [bp + 6]                      ; offset = dst
+    push __STAGE2_SEGMENT                   ; this segment 
+    call BIOS_int13h_ext_read
+    add sp, 0xC
+.check_sig:
+    mov bx, [bp + 6]
+    cmp word [bx + 0x1FE], 0xAA55           ; check for bytes at end
+    jne .error_nosign
+    ; TODO: this needs more error checking, zero checking, check the sig a bunch of stuff...
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+.error_nosign:
+    ERROR STAGE2_ERROR_BAD_MBR
+
+; int read_vbr(int boot_drive, void* buf)
+; read vbr on boot partition to memory (for fat bpb/ebpb)
+; TODO: seperate validation and loading the sector, just check the 0xAA55 at the end here...
+FAT32_load_vbr:
+    __CDECL16_PROC_ENTRY
+.proc:
+    mov bx, SteviaInfo
+    mov ax, word [bx + SteviaInfoStruct_t.p16_MbrPtr]      
+    add ax, DISK_PARTITION_TABLE_OFFSET                           
+    mov bx, ax                              ; offset to part table
+    mov cx, 4                               ; only checking 4 entries
+
+.find_active_L0:
+    mov al, [bx + PartEntry_t.attributes]
+    cmp al, 0x80                            ; 0x80 == 1000_0000b
+    je .check_fstype
+    add bx, PartEntry_t_size                ; next part entry's attributes
+    loop .find_active_L0
+    jmp .error_noactive
+.check_fstype:
+    ; check for part_type = 0x0C (DOS 7.1+/W95 FAT32 w/ LBA) or 0x1C (Hidden 0x0C)
+    __BOCHS_MAGIC_DEBUG
+    mov al, [bx + PartEntry_t.part_type]
+    cmp al, 0x0C
+    je .active_ok
+    ; *or*
+    cmp al, 0x1C
+    je .active_ok
+
+    jmp .error_badparttype        ; error if part_type != 0x1C or 0x0C
+.active_ok:
+    movzx ax, byte [bp + 4]
+    push ax                                 ; drive_num (2)
+    push 0x01                               ; count (2)
+
+    mov eax, dword [bx + PartEntry_t.lba_start]
+    push dword eax                          ; lba (4)
+
+    push word [bp + 6]                      ; offset = dst
+    push __STAGE2_SEGMENT                   ; this segment 
+    call BIOS_int13h_ext_read
+    add sp, 0xC
+    ; vbr (with fat bpb/ebpb) is at the buffer now
+.check_sig:
+    mov bx, [bp + 6]
+    cmp word [bx + 0x1FE], 0xAA55           ; check for bytes at end
+    jne .error_nosign
+.check_FAT_sanity:
+    ; we only quickly validate that this is *probably* a FAT32 volume
+
+    add bx, 11                                             ; point bx at start of bpb (skip jmp code and ident)
+    cmp word [bx + FAT32_bpb_t.u16_TotalSectors16], 0      ; TotalSectors16 should be 0 (use TotalSectors32 in bpb)
+    jne .error_totsectors
+
+    cmp word [bx + FAT32_bpb_t.u16_FATSize16], 0           ; FatSize16 will be 0 if FAT32 (use FATSize32 in ebpb)
+    jne .error_fatsz
+
+    cmp word [bx + FAT32_bpb_t.u16_RootEntryCount16], 0    ; root dir info is in data clusters on fat32
+    jne .error_rootdir
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+.error_noactive:
+    ERROR STAGE2_VBR_E_ACTIVE
+.error_nosign:
+    ERROR STAGE2_VBR_E_SIGN
+.error_totsectors:
+    ERROR STAGE2_VBR_E_TOT
+.error_fatsz:
+    ERROR STAGE2_VBR_E_FATSZ
+.error_rootdir:
+    ERROR STAGE2_VBR_E_DIRENT
+.error_badparttype:
+    ERROR STAGE2_VBR_E_PARTTYPE
+
+; what a 'mount' should probably do at this point...
+; - read VBR at partition_lba
+; - validate FAT32 signatures
+; - fill fat32_bpb_t and compute derived fields
+; - read FSInfo (free count/next free)
+; - ???
+; int fat32_mount(FAT32_State_t* state, uint32_t partition_lba);
+FAT32_mountfs:
+    __CDECL16_PROC_ENTRY
+.proc:
+    ; mount: parse BPB, derive fat0_lba, data_lba, cluster0_lba.
+
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+.error:
+    ERROR STEVIA_DEBUG_ERR
+
+
+; int fat32_read_fat(FAT32_State_t* state, uint32_t clus, uint32_t* out);
+FAT32_read_fat:
+    __CDECL16_PROC_ENTRY
+.proc:
+    ; Read 32-bit FAT entry for cluster n
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+.error:
+    ERROR STEVIA_DEBUG_ERR
+
+; FAT32 entry is 32-bits; only low 28 bits are meaningful.
+;   EOC if (val & 0x0FFFFFFF) >= 0x0FFFFFF8.
+;   bad if == 0x0FFFFFF7.
+;   free if == 0x00000000.
+; int fat32_next_clus(FAT32_State_t* state, uint32_t clus, uint32_t* out_next);
+FAT32_next_cluster:
+    __CDECL16_PROC_ENTRY
+.proc:
+    ; Walk to next cluster in chain (validates EOC/bad)
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+.error:
+    ERROR STEVIA_DEBUG_ERR
+
+; e.g:
+; uint64_t clus_to_lba(FAT32_State_t* state, uint32_t clus) {
+;  return v->data_lba + (uint64_t)(clus - 2) * v->secs_per_clus;
+; }
+FAT32_clus_to_lba:
+    __CDECL16_PROC_ENTRY
+.proc:
+    ; Convert cluster -> LBA of first sector of that cluster
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+.error:
+    ERROR STEVIA_DEBUG_ERR
+
+; Prototyping for now...
+
+; TODO:
+;   - bio_read_sectors (BIOS int13h LBA or CHS) + tiny sector cache.
+;   - mount: parse BPB, derive fat0_lba, data_lba, cluster0_lba.
+;   - FAT read: fat32_read_fat, fat32_next_clus.
+;   - dir iterator (SFN only) + path lookup.
+;   - file reader (fopen/fread) with cluster crossing.
+;   - contiguity probe for speed (optional).
+;   - (later) LFN support & code page handling.
+
+
+; keep count <= 127
+; int bio_read_sectors(uint64_t lba, uint16_t count, void* dst);
+; will also need a bio_bios_int13h() (refactor ext_disk_read?)
+; to abstract the backend 'sector getter'
+
+; Error codes
+
+; FS_OK 0
+; FS_E_IO 1 (bio read failed)
+; FS_E_FMT 2 (not FAT32 or bad BPB)
+; FS_E_RANGE 3 (bad cluster or out of range)
+; FS_E_END 4 (iterator end)
+; FS_E_NOSUCH 5 (file/dir not found)
+; FS_E_ISDIR 6 (opened dir as file)
+; FS_E_TOOLONG 7 (path segment too long for 8.3)
+; FS_E_UNSUPPORTED 8 (LFN present but disabled)
+; FS_E_UNIMPLEMENTED 0xffff (procedure call unimplmented)
+
+;
+; Cache methods
+;
+; TODO: make a cache for ~4-8 disk sectors
+; TODO: make a cache for FATs to avoid having to re-read the FAT
+;
+; // uses bio_read_sectors + cache
+; int cache_read_sector(uint64_t lba, void* dst);   
+; int cache_invalidate_all(void);
+
+;
+; SFN directories
+;
+
+; typedef struct {
+;   char     name83[12];   // "FILENAMEEXT" (no dot), NUL-terminated
+;   uint8_t  attr;         // ATTR_DIRECTORY=0x10, ATTR_VOLUME=0x08
+;   uint32_t first_clus;   // (hi<<16)|lo
+;   uint32_t size;         // bytes
+; } fat32_dirent_sfn_t;
+
+; typedef struct { // iterator
+;   fat32_bpb_t* v;
+;   uint32_t     cur_clus;
+;   uint32_t     offs_in_clus; // byte offset
+; } fat32_dir_iter_t;
+
+;int fat32_dir_iter_open_root(fat32_bpb_t* v, fat32_dir_iter_t* it);
+;int fat32_dir_iter_open(fat32_bpb_t* v, uint32_t first_clus, fat32_dir_iter_t* it);
+;int fat32_dir_iter_next(fat32_dir_iter_t* it, fat32_dirent_sfn_t* out); // FS_OK or FS_E_END
+
+; typedef struct {
+;   uint32_t first_clus;
+;   uint32_t size;
+;   uint8_t  attr; // dir or file
+; } fat32_node_t;
+
+; split by / or \.
+; start at root (v->root_clus).
+; for each component:
+; iterate directory with dir_iter_* to find case-insensitive 8.3 match (fold to upper and space-pad during compare).
+; if final component: return file’s cluster & size.
+; if intermediate: ensure ATTR_DIRECTORY and descend.
+;
+; int fat32_path_lookup(fat32_bpb_t* v, const char* path, fat32_node_t* out);
+
+; an example 'do the thing' proc to load a file to a location
+;
+; // loads file at path into dst, up to max_bytes; returns size read.
+; int fat32_load_file(fat32_bpb_t* v, const char* path, void* dst,
+;                     uint32_t max_bytes, uint32_t* out_size);
+
+; streamed reads
+;
+; typedef struct {
+;   fat32_bpb_t* v;
+;   uint32_t     first_clus;
+;   uint32_t     cur_clus;
+;   uint32_t     cur_clus_index;   // which cluster within file we’re on
+;   uint32_t     size;             // total bytes
+;   uint32_t     pos;              // current byte position
+; } fat32_file_t;
+; 
+; 
+; int fat32_fopen(fat32_bpb_t* v, const char* path, fat32_file_t* f);
+; int fat32_fread(fat32_file_t* f, void* dst, uint32_t nbytes, uint32_t* out_read);
+; int fat32_fseek(fat32_file_t* f, uint32_t new_pos);   // forward seeks only is fine
+; int fat32_fclose(fat32_file_t* f);
+
+
+; an example 'do the thing' proc to load a file to a location
+;
+; // loads file at path into dst, up to max_bytes; returns size read.
+; int fat32_load_file(fat32_bpb_t* v, const char* path, void* dst,
+;                     uint32_t max_bytes, uint32_t* out_size);
+
+
+%endif
+%define __INC_FAT32_SYS
--- a/include/fat32/fat32_structures.inc
+++ b/include/fat32/fat32_structures.inc
@@ -58,20 +58,18 @@
 ;                           resulting in a value which does not fit in the Number of Sectors entry at 0x13. 

 struc FAT32_bpb_t
-    .reserved_jmpboot               resb 3
-    .ident                          resb 8
-    .bytes_per_sector_word          resb 2
-    .sectors_per_cluster_byte       resb 1
-    .reserved_sectors_word          resb 2
-    .fat_count_byte                 resb 1
-    .unused1_ZERO_word              resb 2      ; Root entry count field, 0 on fat32
-    .unused2_ZERO_word              resb 2      ; total sectors size 16, 0 on fat32
-    .media_desc_byte                resb 1
-    .unused3_ZERO_word              resb 2      ; FAT size 16, 0 on fat32
-    .sectors_per_track_word         resb 2
-    .head_count_word                resb 2
-    .hidden_sectors_dword           resb 4
-    .total_sectors_dword            resb 4
+    .u16_BytesPerSector      resw 1
+    .u8_SectorsPerCluster    resb 1
+    .u16_ReservedSectors     resw 1
+    .u8_FatCount             resb 1
+    .u16_RootEntryCount16    resw 1      ; Root dir entry count field, 0 on fat32
+    .u16_TotalSectors16      resw 1      ; total number of sectors size, 0 on fat32
+    .u8_MediaDesc            resb 1
+    .u16_FATSize16           resw 1      ; FAT size 16, 0 on fat32
+    .u16_SectorsPerTrack     resw 1
+    .u16_HeadCount           resw 1
+    .u32_HiddenSectors       resd 1
+    .u32_TotalSectors32      resd 1
 endstruc

 ; EBPB Information (FAT32)
@@ -91,19 +89,19 @@ endstruc
 ;   8 	System identifier string. Always "FAT32   ". The spec says never to trust the contents of this string for any use.

 struc FAT32_ebpb_t
-    .FATSz_dword                resb 4
-    .extflags_word              resb 2
-    .FSVersion_word             resb 2
-    .root_clus_dword            resb 4
-    .FSInfo_word                resb 2
-    .BkBootSec_word             resb 2
-    .reserved1                  resb 12
-    .drive_number_byte          resb 1
-    .nt_flags_byte              resb 1
-    .signature_byte             resb 1
-    .volume_id_dword            resb 4
-    .volume_label_bytea         resb 11
-    .system_ident_bytea         resb 8
+    .u32_FATSize32         resd 1      ; size of *each* fat in sectors, total = FATSz * (# of FATs)
+    .u16_ExtFlags          resw 1
+    .u16_FSVersion         resw 1
+    .u32_RootDirCluster    resd 1
+    .u16_FSInfoSector      resw 1
+    .u16_BkBootSector      resw 1
+    .reserved0             resb 12
+    .u8_DriveNumber        resb 1
+    .u8_NtFlags            resb 1
+    .u8_Signature          resb 1
+    .u32_VolumeId          resd 1
+    .volume_label          resb 11
+    .system_ident          resb 8      ; Should always be 'FAT32   '
 endstruc

 ; ## Standard 8.3 structure ###
@@ -197,20 +195,11 @@ endstruc

 ; 32 bytes
 struc FAT32_State_t
-    .first_data_sector_32     resd 1
-    .first_fat_sector_32      resd 1
-    .fat_size_32              resd 1
-    .curr_FAT_cluster_32      resd 1
-    .curr_dir_cluster_32      resd 1
-    .curr_drive_lba_32        resd 1
-endstruc
-
-; 16 bytes
-struc FAT32_NextClusterData_t
-    .fat_offset               resd 1
-    .fat_sector               resd 1
-    .entry_offset             resd 1
-    .reserved_1               resd 1
+    .u32_TotalClusters        resd 1
+    .u32_DataAreaStartSector  resd 1
+    .u32_FATAreaStartSector   resd 1
+    .p16_FATBuffer            resw 1
+    .p16_ClustBuffer          resw 1
 endstruc

 ; FAT32 Attributes
--- a/include/fat32/old/FAT32_SYS.old.inc
+++ b/include/fat32/old/FAT32_SYS.old.inc
@@ -23,16 +23,11 @@
 ; returns: none
 ALIGN 4, db 0x90
 InitFATDriver:
-    __CDECL16_ENTRY
+    __CDECL16_PROC_ENTRY
 .func:
-    mov ax, FAT32_State_t_size
-    push ax                     ; length of fat32_state structure
-    xor ax, ax
-    push ax                     ; init fat32_state with zero
-    mov ax, fat32_state
-    push ax                     ; address of structure
-    call kmemset
-    sub sp, 0x6
+
+    __CDECL16_CALL_ARGS fat32_state, 0x0000, FAT32_State_t_size
+    __CDECL16_CALL kmemset, 3

 .calc_active_part:
    mov ax, word [partition_offset]            
@@ -70,14 +65,14 @@ InitFATDriver:
    mov eax, dword [bx + FAT32_ebpb_t.root_clus_dword]
    mov dword [di + FAT32_State_t.curr_dir_cluster_32], eax
 .endp:
-    __CDECL16_EXIT
+    __CDECL16_PROC_EXIT
    ret
 .error:
    ERROR STAGE2_FAT32_INIT_CF

 ALIGN 4, db 0x90
 FSInfoPrinter:
-    __CDECL16_ENTRY
+    __CDECL16_PROC_ENTRY
 .func:
    ;info we want to print to validate we are loading stuff from the disk correctly
    ; boot_drive # (i.e 0x80)
@@ -88,7 +83,7 @@ FSInfoPrinter:
    ; print entire FAT32 state
    ;
 .endp:
-    __CDECL16_EXIT
+    __CDECL16_PROC_EXIT
    ret
 .error:
    ERROR STAGE2_ERROR_INFOPRINTER
@@ -104,18 +99,19 @@ FSInfoPrinter:
 ; uint32_t SearchFATDIR(uint8_t* SFN);
 ALIGN 4, db 0x90
 SearchFATDIR:
-    __CDECL16_ENTRY
+    __CDECL16_PROC_ENTRY
 .file_lookup:
-    print_string SearchFATDIR_info
+    __CDECL16_CALL_ARGS SearchFATDIR_info
+    __CDECL16_CALL PrintString, 1
+
    mov bx, fat32_state
    .load_first_dir:
-        mov eax, dword [bx + FAT32_State_t.curr_dir_cluster_32]
-        push dword eax          ; cluster
-        mov ax, dir_buffer
-        push ax                 ; offset
-        xor ax, ax
-        push ax                 ; segment
-        call ReadFATCluster     ; uint8_t ReadFATCluster(uint16_t seg, uint16_t offset, uint32_t cluster)
+
+        ; uint8_t ReadFATCluster(uint16_t seg, uint16_t offset, uint32_t cluster)
+        push dword [bx + FAT32_State_t.curr_dir_cluster_32]          ; cluster
+        push dir_buffer                                              ; offset
+        push 0x0000                                                  ; segment
+        call ReadFATCluster
        add sp, 0x8

        mov si, dir_buffer
@@ -125,9 +121,9 @@ SearchFATDIR:
        ; if eax >= 0x0FFFFFF8 then there are no more clusters (end of chain)
        ; if eax == 0x0FFFFFF7 then this is a cluster that is marked as bad

-        mov eax, dword [bx + FAT32_State_t.curr_dir_cluster_32]
-        push dword eax
-        call NextCluster        ; uint32_t NextCluster(uint32_t active_cluster);
+        ; uint32_t NextCluster(uint32_t active_cluster);
+        push dword [bx + FAT32_State_t.curr_dir_cluster_32]
+        call NextCluster        
        add sp, 0x4

        cmp eax, 0x0fff_fff7
@@ -137,16 +133,14 @@ SearchFATDIR:

    .load_next_dir_next_OK:
        ; load 512 bytes of directory entries from data sector
-        mov eax, [bx + FAT32_State_t.curr_dir_cluster_32]
-        push dword eax          ; cluster

-        mov ax, dir_buffer    
-        push ax                 ; offset
+        ; uint8_t ReadFATCluster(uint16_t seg, uint16_t offset, uint32_t cluster)
+        push dword [bx + FAT32_State_t.curr_dir_cluster_32] ; cluster   
+        push dir_buffer                                     ; offset
+        push 0x0000                                         ; segment
+        call ReadFATCluster     
+        add sp, 0x8

-        xor ax, ax
-        push ax                 ; segment
-        call ReadFATCluster     ; uint8_t ReadFATCluster(uint16_t seg, uint16_t offset, uint32_t cluster)
-        sub sp, 0x8
    .empty_dir_entry:
        ; check for 0x0 in first byte, if true then there are no more files
        ; if true we did not find the file, we should error here
@@ -176,7 +170,9 @@ SearchFATDIR:

    ; TODO: move this to a seperate string search function
    .parse_dir:
-        print_string MaybeFound_Boot_info
+        __CDECL16_CALL_ARGS MaybeFound_Boot_info
+        __CDECL16_CALL PrintString, 1
+        
        .lfn_check:
            ; check for ATTR_READ_ONLY | ATTR_HIDDEN | ATTR_SYSTEM | ATTR_VOLUME_ID  (0x0F) in offset 11
            ; TODO: going to skip LFN for now, since all valid volumes will have SFN's
@@ -201,7 +197,7 @@ SearchFATDIR:
            mov ax, [si + FAT32_SFN_t.cluster_16_low]
            ; eax == first cluster of file
 .endp:
-    __CDECL16_EXIT
+    __CDECL16_PROC_EXIT
    ret

 ; BUG: this function needs review
@@ -210,20 +206,15 @@ SearchFATDIR:
 ; if eax == 0x0FFFFFF7 then this is a cluster that is marked as bad
 ALIGN 4, db 0x90
 NextCluster:
-    __CDECL16_ENTRY
+    __CDECL16_PROC_ENTRY
 .func:
-    print_string NextFATCluster_info
+    __CDECL16_CALL_ARGS NextFATCluster_info
+    __CDECL16_CALL PrintString, 1

-    mov ax, FAT32_NextClusterData_t_size
-    push ax                     ; length
-    xor ax, ax
-    push ax                     ; init with zero
-    mov ax, fat32_nc_data
-    push ax                     ; address of structure
-    call kmemset
-    sub sp, 0x6
+    __CDECL16_CALL_ARGS fat32_nc_data, 0x0000, FAT32_NextClusterData_t_size
+    __CDECL16_CALL kmemset, 3

-    mov edx, dword [bp + 4]
+    mov edx, dword [bp + 4]                      ; active_cluster
    mov si, fat32_nc_data                        ; instead of push/pop and moving the data back
    mov di, fat32_bpb                            ; load si & di then use xchg
    mov bx, fat32_state
@@ -270,12 +261,13 @@ NextCluster:
 ;                         uint32_t lba,
 ;                         uint16_t count, uint16_t drive_num)
 .read_cluster:
-; next_cluster = fat_buffer[entry_offset]
+    ; next_cluster = fat_buffer[entry_offset]
    mov ebx, dword [si + FAT32_NextClusterData_t.entry_offset]
    mov si, fat_buffer
    mov eax, dword [bx+si+0]
+    ; BUG: ???
 .endp:
-    __CDECL16_EXIT
+    __CDECL16_PROC_EXIT
    ret
 .error_cfdivz:
    ERROR STAGE2_FAT32_NCLUS_CFDIVZ
@@ -283,9 +275,10 @@ NextCluster:
 ; uint8_t ReadFATCluster(uint16_t seg, uint16_t offset, uint32_t cluster)
 ALIGN 4, db 0x90
 ReadFATCluster:
-    __CDECL16_ENTRY
+    __CDECL16_PROC_ENTRY
 .func:
-    print_string ReadFATCluster_info
+    __CDECL16_CALL_ARGS ReadFATCluster_info
+    __CDECL16_CALL PrintString, 1

    mov bx, fat32_bpb
    mov si, fat32_ebpb
@@ -318,7 +311,7 @@ ReadFATCluster:
    call read_disk_raw  
    add sp, 0xC
 .endp:
-    __CDECL16_EXIT
+    __CDECL16_PROC_EXIT
    ret
 .error:
    ERROR STAGE2_FAT32_CLS2LBA_CF
--- a/include/fat32/old/bpb_offset_bx.inc
+++ b/include/fat32/old/bpb_offset_bx.inc
--- a/include/fat32/old/fat32_structures.inc
+++ b/include/fat32/old/fat32_structures.inc
@@ -0,0 +1,228 @@
+; Copyright (C) 2025 Elaina Claus
+; 
+;     This program is free software: you can redistribute it and/or modify
+;     it under the terms of the GNU General Public License as published by
+;     the Free Software Foundation, either version 3 of the License, or
+;     (at your option) any later version.
+; 
+;     This program is distributed in the hope that it will be useful,
+;     but WITHOUT ANY WARRANTY; without even the implied warranty of
+;     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;     GNU General Public License for more details.
+; 
+;     You should have received a copy of the GNU General Public License
+;     along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+%ifndef __INC_FAT32_STRUCT
+
+; ## FAT32 Info ##
+;   total_sectors = bsSectorsHuge
+;   fat_size = bsSectorsPerFat
+; 
+;       first_data_sector = bsResSectors + (bsFATs * bsSectPerFAT);
+;       total_data_sectors = bsSectorsHuge - (bsResSectors + (bsFATs * bsSectPerFAT));
+;       total_clusters = total_data_sectors / bsSectsPerClust
+;       first_fat_sector = bsResSectors
+;
+; ## FAT32 Table information ##
+;
+;   fat_offset = active_cluster * 4
+;   fat_sector = first_fat_sector + (fat_offset / sector_size)
+;   entry_offset = fat_offset % sector_size
+;   
+;   table_value = fat_table[entry_offset] & 0x0FFF_FFFF
+;
+; ## FAT32 Directory Entries ##
+;   root_dir_cluster = bsRootDirCluster
+;   root_dir_sectors = ? (this is varible on FAT32 since the root dir is a cluster chain)
+;   first_sector_of_cluster = ((cluster - 2) * bsSectPerClust) + first_data_sector;
+
+; BPB Information
+; Size   Description
+;   8 	OEM identifier.
+;   2 	The number of Bytes per sector (remember, all numbers are in the little-endian format).
+;   1 	Number of sectors per cluster.
+;   2 	Number of reserved sectors. The boot record sectors are included in this value.
+;   1 	Number of File Allocation Tables (FAT's) on the storage media. Often this value is 2.
+;   2 	Number of directory entries (must be set so that the root directory occupies entire sectors).
+;   2 	The total sectors in the logical volume. 
+;            If this value is 0, it means there are more than 65535 sectors in the volume, 
+;            and the actual count is stored in the Large Sector Count entry at 0x20.
+;
+;   1 	This Byte indicates the media descriptor type.
+;   2 	Number of sectors per FAT. FAT12/FAT16 only.
+;   2 	Number of sectors per track.
+;   2 	Number of heads or sides on the storage media.
+;   4 	Number of hidden sectors. (i.e. the LBA of the beginning of the partition.)
+;   4 	Large sector count. This field is set if there are more than 65535 sectors in the volume, 
+;                           resulting in a value which does not fit in the Number of Sectors entry at 0x13. 
+
+struc FAT32_bpb_t
+    .reserved_jmpboot               resb 3
+    .ident                          resb 8
+    .bytes_per_sector_word          resb 2
+    .sectors_per_cluster_byte       resb 1
+    .reserved_sectors_word          resb 2
+    .fat_count_byte                 resb 1
+    .unused1_ZERO_word              resb 2      ; Root entry count field, 0 on fat32
+    .unused2_ZERO_word              resb 2      ; total sectors size 16, 0 on fat32
+    .media_desc_byte                resb 1
+    .unused3_ZERO_word              resb 2      ; FAT size 16, 0 on fat32
+    .sectors_per_track_word         resb 2
+    .head_count_word                resb 2
+    .hidden_sectors_dword           resb 4
+    .total_sectors_dword            resb 4
+endstruc
+
+; EBPB Information (FAT32)
+; Size   Description
+;   4 	Sectors per FAT. The size of the FAT in sectors.
+;   2 	Flags.
+;   2 	FAT version number. The high byte is the major version and the low byte is the minor version. FAT drivers should respect this field.
+;   4 	The cluster number of the root directory. Often this field is set to 2.
+;   2 	The sector number of the FSInfo structure.
+;   2 	The sector number of the backup boot sector.
+;   12 	Reserved. When the volume is formated these bytes should be zero.
+;   1 	Drive number. The values here are identical to the values returned by the BIOS interrupt 0x13. 0x00 for a floppy disk and 0x80 for hard disks.
+;   1 	Flags in Windows NT. Reserved otherwise.
+;   1 	Signature (must be 0x28 or 0x29).
+;   4 	Volume ID 'Serial' number. Used for tracking volumes between computers. You can ignore this if you want.
+;   11 	Volume label string. This field is padded with spaces.
+;   8 	System identifier string. Always "FAT32   ". The spec says never to trust the contents of this string for any use.
+
+struc FAT32_ebpb_t
+    .FATSz_dword                resb 4
+    .extflags_word              resb 2
+    .FSVersion_word             resb 2
+    .root_clus_dword            resb 4
+    .FSInfo_word                resb 2
+    .BkBootSec_word             resb 2
+    .reserved1                  resb 12
+    .drive_number_byte          resb 1
+    .nt_flags_byte              resb 1
+    .signature_byte             resb 1
+    .volume_id_dword            resb 4
+    .volume_label_bytea         resb 11
+    .system_ident_bytea         resb 8
+endstruc
+
+; ## Standard 8.3 structure ###
+;   Offset      Length (Bytes)      Description
+;   0               11              8.3 file name. The first 8 characters are the name and the last 3 are the extension.
+;   11              1               File Atrributes
+;                                      READ_ONLY=0x01 
+;                                      HIDDEN=0x02 
+;                                      SYSTEM=0x04 
+;                                      VOLUME_ID=0x08 
+;                                      DIRECTORY=0x10 
+;                                      ARCHIVE=0x20 
+;                                      LFN=READ_ONLY|HIDDEN|SYSTEM|VOLUME_ID == 0x0F
+;
+;   12              1                NT Reserved
+;   13              1                Creation time in tenths of a second.
+;   14              2                File creation time, Hour 5 bits, Minutes 6 bits, Seconds 5 Bits, multiply seconds by 2
+;   16              2                File creation date, Year 7 bits, month 4 bits, day 5 bits
+;   18              2                Last Accessed date. same format at creation date
+;   20              2                High 16 bits of entry's first cluster
+;   22              2                Last modification time. same format at creation time
+;   24              2                Last modification date. same format as creation date
+;   26              2                Low 16 bits of entry's first cluster
+;   28              4                File size in bytes
+
+; FSInfo 
+; 0 	0x0 	4 	    Lead signature (must be 0x41615252 to indicate a valid FSInfo structure)
+; 4 	0x4 	480 	Reserved, these bytes should never be used
+; 484 	0x1E4 	4 	    Another signature (must be 0x61417272)
+; 488 	0x1E8 	4 	    Contains the last known free cluster count on the volume. If the value is 0xFFFFFFFF, then the free count is unknown and must be computed. 
+;                       However, this value might be incorrect and should at least be range checked (<= volume cluster count)
+;
+; 492 	0x1EC 	4 	    Indicates the cluster number at which the filesystem driver should start looking for available clusters. 
+;                       If the value is 0xFFFFFFFF, then there is no hint and the driver should start searching at 2. 
+;                       Typically this value is set to the last allocated cluster number. As the previous field, this value should be range checked.
+;
+; 496 	0x1F0 	12 	    Reserved
+; 508 	0x1FC 	4 	    Trail signature (0xAA550000)
+
+struc FAT32_FSInfo_t
+    .head_sig_dword         resd 1          ; 0x41615252
+    .reserved1              resb 480        ; fill zero
+    .body_sig_dword         resd 1          ; 0x61417272
+    .free_count_dword       resd 1
+    .next_free_dword        resd 1
+    .reserved2              resb 12         ; fill zero
+    .tail_sig_dword         resd 1          ; 0xAA550000
+endstruc
+
+struc FAT32_SFN_t
+    .label_83               resb 11
+    .attributes_byte        resb 1
+    .nt_res_byte            resb 1
+    .csec_byte              resb 1
+    .ctime_word             resb 2
+    .cdate_word             resb 2
+    .adate_word             resb 2
+    .cluster_16_high        resb 2
+    .mtime_word             resb 2
+    .mdate_word             resb 2
+    .cluster_16_low         resb 2
+    .size_dword             resb 4
+endstruc
+
+; ## Long file name (LFN) structure format ##
+;
+; 0 	1 	The order of this entry in the sequence of long file name entries. This value helps you to know where in the file's name the characters from this entry should be placed.
+; 1 	10 	The first 5, 2-byte characters of this entry.
+; 11 	1 	Attribute. Always equals 0x0F. (the long file name attribute)
+; 12 	1 	Long entry type. Zero for name entries.
+; 13 	1 	Checksum generated of the short file name when the file was created. The short filename can change without changing the long filename in cases where the partition is mounted on a system which does not support long filenames.
+; 14 	12 	The next 6, 2-byte characters of this entry.
+; 26 	2 	Always zero.
+; 28 	4 	The final 2, 2-byte characters of this entry. 
+;
+; LFN entries are always placed immediately before their respective 8.3 entry
+; 
+; LAST_LFN_ENTRY == 0x40
+; Max of 20 in sequence == 0x14
+
+struc FAT32_LFN_t
+    .order                  resb 1
+    .lfn_first5             resb 10
+    .attributes_8           resb 1
+    .zero1                  resb 1
+    .checksum               resb 1
+    .lfn_next6              resb 12
+    .zero2                  resb 2
+    .lfn_last2              resb 4
+endstruc
+
+; 32 bytes
+struc FAT32_State_t
+    .first_data_sector_32     resd 1
+    .first_fat_sector_32      resd 1
+    .fat_size_32              resd 1
+    .curr_FAT_cluster_32      resd 1
+    .curr_dir_cluster_32      resd 1
+    .curr_drive_lba_32        resd 1
+endstruc
+
+; 16 bytes
+struc FAT32_NextClusterData_t
+    .fat_offset               resd 1
+    .fat_sector               resd 1
+    .entry_offset             resd 1
+    .reserved_1               resd 1
+endstruc
+
+; FAT32 Attributes
+%define FAT32_ATTR_RO           0x01
+%define FAT32_ATTR_HIDDEN       0x02
+%define FAT32_ATTR_SYSTEM       0x04
+%define FAT32_ATTR_VOLID        0x08
+%define FAT32_ATTR_DIR          0x10
+%define FAT32_ATTR_ARC          0x20
+
+; LFN == RO | HIDDEN | SYSTEM | VOLID == 0x0F
+%define FAT32_ATTR_LFN          0x0F
+
+%endif
+%define __INC_FAT32_STRUCT
--- a/include/partition_table.inc
+++ b/include/partition_table.inc
@@ -15,6 +15,9 @@

 %ifndef __INC_PART_TABLE

+%define DISK_SIGNATURE_OFFSET 0x1B8
+%define DISK_PARTITION_TABLE_OFFSET 0x1BE
+
 ; Partition table entry format
 ; Off.  Size.       Description
 ;0x00 	  1 	Drive attributes (bit 7 set = active or bootable)
@@ -34,8 +37,6 @@ struc PartEntry_t
 endstruc

 struc PartTable_t
-    .signature resb 4
-    .reserved  resb 2
    .partition1 resb PartEntry_t_size
    .partition2 resb PartEntry_t_size
    .partition3 resb PartEntry_t_size
--- a/include/util/arena_alloc.nasm
+++ b/include/util/arena_alloc.nasm
@@ -0,0 +1,164 @@
+%ifndef __INC_ARENA_ALLOC_FUNC
+
+%define __ARENA_HEAP_START 0x8000
+%define __ARENA_HEAP_SIZE  0x6000   ; 0x8000 -> 0xE000 = 24KiB of Heap
+
+struc ArenaStateStruc_t
+    .start resw 1
+    .end resw 1
+    .mark resw 1
+endstruc
+
+; void arena_init(ArenaState *a)
+;
+ArenaInit:
+    __CDECL16_PROC_ENTRY
+.proc:
+    mov ax, word [bp + 4]     ; ptr to state structure
+    mov di, ax
+
+    xor ax, ax
+    mov word [di + ArenaStateStruc_t.mark], ax
+    mov word [di + ArenaStateStruc_t.end], word (__ARENA_HEAP_START + __ARENA_HEAP_SIZE)
+    mov word [di + ArenaStateStruc_t.start], __ARENA_HEAP_START
+
+    ; zero out heap area on init
+    ; void* kmemset_byte(void* dst, uint8_t val, uint16_t len);
+    ; TODO: use word or qword spacing at least to speed this up
+    push __ARENA_HEAP_SIZE       ; len
+    push 0x0                     ; val = 0
+    push __ARENA_HEAP_START      ; dst
+    call kmemset
+    add sp, 0x6
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+
+; size_t align_up(size_t x, size_t a)
+; ax, bx. cx are all clobbered
+; align x up to the nearest specified alignment (a), a should be a power of 2
+; (x + (a-1)) & ~(a-1)
+; return value in ax
+ArenaAlignUp:
+    __CDECL16_PROC_ENTRY
+.func:
+    ; if a == 0 return x
+    mov ax, [bp + 4]      ; x
+    mov bx, [bp + 6]      ; a
+
+    test bx, bx
+    jz .endf              
+
+    ; enforce power-of-two for alignment, return x
+    ; for example...
+    ; alignment = 0x0010,
+    ;    0x0010 & (0x0010 - 0x0001)
+    ;    0x0010 & 0x000F -> 1_0000000b & 0_11111111b => 0b == zero
+    ;
+    ; alignment = 0x0006
+    ;    0x0006 & (0x0006 - 0x0001)
+    ;    0x0006 & 0x0005 -> 00000110b & 00000101b => 00000100b != 0
+    ;
+    ; i.e any power of 2 has only 1 bit set in binary (2 = 0010b, 4 = 0100b, 8 = 1000b and so on)
+    ;  subtracting 1 from a power of 2 'flips' lower bits ( 7 = 0111b, 15 = 1111b ...) 
+    ;  so 'and'ing a power of two with (itself - 1) will result in none of the bit's being set
+    mov cx, bx
+    dec cx
+    test bx, cx
+    jnz .endf
+
+    dec bx                ; a - 1
+
+    mov cx, ax
+    add cx, bx            ; x + (a-1)
+    not bx                ; ~(a-1)
+
+    and cx, bx            ; and with the inverse
+
+    mov ax, cx            ; move to ax and return
+.endf:
+    __CDECL16_PROC_EXIT
+    ret
+
+; void* arena_alloc(size_t bytes, size_t align)
+; bp-2 - current used arena (i.e 'highmark')
+; bp-4 - aligned_ptr 
+; bp-6 - new_end
+ArenaAlloc:
+    __CDECL16_PROC_ENTRY 0x10
+.proc:
+    ; remove bytes from pool and increment mark to the new cursor location
+    ; return a pointer to the begining of  allocated segment
+    mov bx, early_heap_state
+    
+    mov ax, word [bx + ArenaStateStruc_t.start]
+    mov dx, word [bx + ArenaStateStruc_t.mark]
+    add ax, dx                      ; i.e the total used arena
+    mov word [bp - 2], ax           ; save as a local
+
+    push bx                         ; save heap_state pointer
+
+              
+    push word [bp + 6]              ; requested next allocation alignment     
+    push word [bp - 2]              ; current arena 'highmark'
+    call ArenaAlignUp
+    add sp, 0x4
+    mov word [bp - 4], ax           ; save return value
+
+    pop bx                          ; restore heap_state pointer
+
+    ; new_end = aligned_ptr + bytes 
+    add ax, word [bp + 4]           ; add to total (so current aligned mark + bytes)
+    mov word [bp - 6], ax           ; save as local
+
+    mov dx, word [bx + ArenaStateStruc_t.end]
+    cmp ax, dx
+    ja .error                       ; if our heap end is < the requested throw an error, heap is full
+                                    ; else update the mark to the new value & return  the aligned pointer
+
+    ; mark_delta = new_end - curr_used
+    mov dx, word [bp - 6]
+    sub dx, word [bp - 2]
+
+    ; mark += mark_delta
+    mov ax, word [bx + ArenaStateStruc_t.mark]
+    add ax, dx
+    mov word [bx + ArenaStateStruc_t.mark], ax
+    
+    ; return aligned_ptr
+    mov ax, word [bp - 4]
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+.error:
+    ERROR STEVIA_DEBUG_ERR
+
+arena_mark:
+    __CDECL16_PROC_ENTRY
+.proc:
+    ; return the current location of the 'cursor' in the allocator
+    ERROR STEVIA_DEBUG_UNIMPLEMENTED
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+
+arena_reset_to:
+    __CDECL16_PROC_ENTRY
+.proc:
+    ; rewind the arena to a previously marked point
+    ERROR STEVIA_DEBUG_UNIMPLEMENTED
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+
+arena_reset:
+    __CDECL16_PROC_ENTRY
+.proc:
+    ; reset the entire heap to a fresh state
+    ERROR STEVIA_DEBUG_UNIMPLEMENTED
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+
+%endif
+%define __INC_ARENA_ALLOC_FUNC
--- a/include/util/kmem_func.nasm
+++ b/include/util/kmem_func.nasm
@@ -19,7 +19,7 @@
 ; void* kmemset_byte(void* dst, uint8_t val, uint16_t len);
 ALIGN 4, db 0x90
 kmemset:
-    __CDECL16_ENTRY
+    __CDECL16_PROC_ENTRY
 .func:
    mov     cx, [bp + 8]        ; uint16_t len
    mov     al, byte [bp + 6]   ; uint8_t val
@@ -29,14 +29,14 @@ kmemset:
    rep     stosb
    mov     ax, di         ; return pointer to dest + len (last elem of dest)
 .endp:
-    __CDECL16_EXIT
+    __CDECL16_PROC_EXIT
    ret

 ; uint8_t* kmemset(uint16_t* dest, uint16_t* src, uint16_t len);
 ; not overlap safe
 ALIGN 4, db 0x90
 kmemcpy:
-    __CDECL16_ENTRY
+    __CDECL16_PROC_ENTRY
 .func:
    mov cx, [bp + 8]        ; len
    mov si, [bp + 6]        ; src
@@ -46,7 +46,7 @@ kmemcpy:
    rep movsb
    mov ax, di              ; return pointer to dest
 .endf:
-    __CDECL16_EXIT
+    __CDECL16_PROC_EXIT
    ret

 %endif
--- a/include/util/kmemcpy5_func.nasm
+++ b/include/util/kmemcpy5_func.nasm
@@ -20,7 +20,7 @@
 ; not overlap safe, only for
 ALIGN 4, db 0x90
 kmemcpy5:
-    __CDECL16_ENTRY
+    __CDECL16_PROC_ENTRY
    push ds
    push es
 .setup_segments:
@@ -41,7 +41,7 @@ kmemcpy5:
    pop es
    pop ds
 .endf:
-    __CDECL16_EXIT
+    __CDECL16_PROC_EXIT
    ret

 %define __INC_KMEMCPY5_FUNC
--- a/include/util/kmemset4_func.nasm
+++ b/include/util/kmemset4_func.nasm
@@ -19,7 +19,7 @@
 ; word kmemset_byte(word segment, word dst, byte val, word len);
 ALIGN 4, db 0x90
 kmemset4:
-    __CDECL16_ENTRY
+    __CDECL16_PROC_ENTRY
 .setup_segment:
    push es
    mov ax, [bp + 4]
@@ -35,7 +35,7 @@ kmemset4:
 .restore_segments:
    pop es
 .endf:
-    __CDECL16_EXIT
+    __CDECL16_PROC_EXIT
    ret

 %endif
--- a/scripts/create-disk.sh
+++ b/scripts/create-disk.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+set -euo pipefail

 # Copyright (C) 2025 Elaina Claus
 # 
@@ -15,246 +16,161 @@
 #     You should have received a copy of the GNU General Public License
 #     along with this program.  If not, see <https://www.gnu.org/licenses/>.

-if ! [ $(id -u) = 0 ]; then
-   echo "Script must be run as root!" >&2
-   exit 1
+if [ $(id -u) = 0 ]; then
+   echo "Script should not be run as root, it could break something!" >&2
 fi

 # paths to bootcode
-mbr_file=build/mbr.bin
-vbr_file=build/vbr.bin
-stage2_file=build/stage2.bin
-boottest_file=build/BOOTi686.bin
-
+mbr_file=build/mbr/mbr.bin
+vbr_file=build/vbr/vbr.bin
+stage2_file=build/stage2/stage2.bin
+boottest_file=build/miniboot32/BOOTi686.bin

 # Disk creation options
-mount_point=/tmp/stevia_disk
-disk_tmp_file=/tmp/disk.img
-disk_file_final=./disk.img.gz
+disk_img=build/disk.img
+disk_img_final=build/output/disk.img.gz
+
+part_img=build/part.img
+part_img_final=build/output/part.img.gz
+
+artifacts_archive=build/output/artifacts.tar.gz

 # $disk_sector_size * $disk_size = total bytes, default is 256MiB
-disk_size=(524288 * 2)
+disk_sectors=(524288 * 2)
 disk_sector_size=512
+part_start=2048
+part_sectors=$((disk_sectors - part_start))

-if ! [ -e $disk_tmp_file ]; then
+#
+# Build sanity section
+#
+
+echo "*** Performing pre-build sanity checks ***"
+
+# Tools needed:
+#   sfdisk dosfstools (mkfs.fat), mtools (mcopy,mmd), gzip, dd, truncate, awk
+for t in mcopy mmd gzip dd truncate awk; do
+  command -v "$t" >/dev/null || { echo "Missing tool: $t" >&2; exit 1; }
+done
+
+# these are normally in the sbin paths so I've had issues detecting them with command -v
+SF=$(command -v sfdisk || echo /usr/sbin/sfdisk)
+MKFS=$(command -v mkfs.fat || echo /usr/sbin/mkfs.fat)
+
+[[ -x "$SF" ]] || { echo "sfdisk not found"; exit 1; }
+[[ -x "$MKFS" ]] || { echo "mkfs.fat not found"; exit 1; }
+
+# check that required build files exist
+for f in "$mbr_file" "$vbr_file" "$stage2_file" "$boottest_file"; do
+  [[ -f "$f" ]] || { echo "missing $f" >&2; exit 1; }
+done
+
+cat > /tmp/pt.sfdisk <<EOF
+label: dos
+unit: sectors
+sector-size: $disk_sector_size
+label-id: 0xa0b0c0d0
+
+start=$part_start, size=$((disk_sectors - part_start)), type=c, bootable
+EOF
+
+mtool_src=/tmp/mtools.conf
+cat > $mtool_src <<EOF
+drive c: file="$part_img"
+EOF
+
+#
+# Create disk images
+#
+
+echo "[1/7] Create disk.img and part.img"
+
+if ! [ -e "$disk_img" ]; then
    # create raw disk image
-    if ! dd if=/dev/zero of=$disk_tmp_file bs=$disk_sector_size count=$disk_size; then
+    if ! truncate -s $((disk_sectors * disk_sector_size)) "$disk_img"; then
        echo "Failed creating blank disk image." >&2
        exit 1
    fi
    sync
 else
    echo "Removing old disk image..."
-    rm -rfv $disk_tmp_file
-    if ! dd if=/dev/zero of=$disk_tmp_file bs=$disk_sector_size count=$disk_size; then
+    rm -rfv "$disk_img"
+    if ! truncate -s $((disk_sectors * disk_sector_size)) "$disk_img"; then
        echo "Failed creating blank disk image." >&2
        exit 1
    fi
    sync
 fi

+if ! [ -e "$part_img" ]; then
+    # create raw partition disk image
+    if ! truncate -s $((part_sectors * disk_sector_size)) "$part_img"; then
+        echo "Failed creating blank partition image." >&2
+        exit 1
+    fi
+    sync
+else
+    echo "Removing old (partition) disk image..."
+    rm -rfv "$part_img"
+    if ! truncate -s $((part_sectors * disk_sector_size)) "$part_img"; then
+        echo "Failed creating blank partition image." >&2
+        exit 1
+    fi
+    sync
+fi
+
+
 if [[ "$OSTYPE" == "linux-gnu"* ]]; then
-        if [ -e $mbr_file ] && [ -e $vbr_file ]; then
-        # get next loop device and mount it
-        ld=$(losetup -f)
-        losetup -P -b 512 $ld $disk_tmp_file
+        echo "[2/7] Write DOS partition table (single FAT32 LBA @ 2048)"
+        "$SF" --no-reread "$disk_img" < /tmp/pt.sfdisk

-        # create a DOS disk, with 1 FAT32 partition that is bootable, part1 starts at sector 2048
-        sfdisk $ld < scripts/loop_setup.sfdisk
+        # BUG: the default disk img is 256MiB which mkfs.fat wants to create
+        #      a FAT16 FS by default. it needs to be at least 2GiB to to 'lock out'
+        #      FAT16 as an option. Force FAT32 here, might(?) break some things.
+        echo "[3/7] Make FAT filesystem in partition image"
+        "$MKFS" -F32 -v -n 'STEVIAFS' "$part_img"

-        # get first partition, this is sloppy might need to review this...
-        firstpart=$(lsblk -ilp -o NAME $ld | tr '\n' ' ' | awk '{print $3}')
-        mkfs.fat -v -F32 -s 1 -n 'STEVIAFS' $firstpart
+        echo "[4/7] Patch VBR inside partition image (preserve BPB)"

-        #
-        # MBR setup
-        #
-
-        # copy MBR while preserving partition table
-        if ! dd if=$mbr_file of=$ld bs=1 count=440; then
-            echo "Failed to write MBR to disk. (part 1)" >&2
-            exit 1
-        fi
-
-        # copy MBR 0xAA55
-        if ! dd if=$mbr_file of=$ld bs=1 seek=510 skip=510 count=2; then
-            echo "Failed to write MBR to disk. (part 2)" >&2
-            exit 1
-        fi
-
-        #
-        # VBR Setup & backup VBR
-        # 
-
-        # copy VBR to partition 1 while preserving partition information
        # copy jmp short entry; nop
-        if ! dd if=$vbr_file of=$firstpart bs=1 count=3; then
-            echo "Failed to write VBR to disk. (part 1)" >&2
-            exit 1
-        fi
+        dd if=$vbr_file of="$part_img" bs=1 count=3 conv=notrunc
        # copy bootcode
-        if ! dd if=$vbr_file of=$firstpart bs=1 seek=90 skip=90 count=420; then
-            echo "Failed to write VBR to disk. (part 2)" >&2
-            exit 1
-        fi
-        # copy 0xAA55
-        if ! dd if=$vbr_file of=$firstpart bs=1 seek=510 skip=510 count=2; then
-            echo "Failed to write VBR to disk. (part 3)" >&2
-            exit 1
-        fi
-
-        # write backup VBR
-        if ! dd if=$firstpart of=$firstpart bs=$disk_sector_size count=1 seek=6; then
-            echo "Failed to copy VBR (sector 1) to backup VBR." >&2
-            exit 1
-        fi
-
-
-        #
-        # Stage2 Setup
-        #
-
-        #stage2 to sectors 1-64
-        if ! dd if=$stage2_file of=$ld bs=$disk_sector_size seek=1; then
-            echo "Failed to write Stage2 to disk." >&2
-            exit 1
-        fi
-
-        # copy boot32 boot test file to disk image
-        if ! [ -e $mount_point ]; then
-            mkdir $mount_point
-        fi
-        mount $firstpart $mount_point
-
-        # ensure mountpoint is actually a mountpoint
-        if ! mountpoint -q $mount_point; then
-            echo "Failed to mount partition at $mount_point." >&2
-            exit 1
-        fi
-
-        # copy kernel to filesystem 
-        if [ -e $boottest_file ]; then
-            cp -v $boottest_file $mount_point/BOOT.BIN
-        else
-            echo "Failed to write $boottest_file to disk image" >&2
-            exit 1
-        fi
-
-        #
-        # Final Cleanup
-        #
-
-        # detach loop device
-        umount $mount_point
-        sync
-        sleep 1
-        losetup -d $ld
-
-        # chown to the real user to prevent issues with reading/writing the file later
-        # BUG: ${logname}:$(id $(logname -g)) doesn't work right on WSL because of runlevel hacks in WSL
-        # BUG: https://github.com/microsoft/WSL/issues/1761
-        # as a work around I'll just reference LICENSE.md...WHICH SHOULD ALWAYS BE THERE 👀
-        chown --from=root:root --reference=LICENSE.md $disk_tmp_file
-
-    else
-        echo "unable to find MBR/VBR binaries!" >&2
-        exit 1
-    fi
-# requires util-linux from homebrew
-elif [[ "$OSTYPE" == "darwin"* ]]; then
-        sfdisk_path="/usr/local/opt/util-linux/sbin/sfdisk"
-        if [ -e $mbr_file ] && [ -e $vbr_file ]; then
-        # use hdiutil to attach our empty disk image
-        ld_path_raw=$(hdiutil attach -readwrite -imagekey diskimage-class=CRawDiskImage -nomount -blocksize 512 -noverify /tmp/disk.img)
-        ld=$(echo $ld_path_raw | sed s:/dev/::)
-        ld_path="/dev/$ld"
-
-        # create a DOS disk, with 1 FAT32 partition
-        if ! [ -e $sfdisk_path ]; then
-            echo "sfdisk utility was not found...We cannot use diskutil to make disks due to the fact that it only makes Hybrid MBR's & GPT disks...blame Apple"
-            exit 4
-        else
-            $sfdisk_path $ld_path < scripts/loop_setup.sfdisk
-        fi
-
-        # give stuff a chance to settle, macOS has problems here
-        sync
-        sleep .5
-
-        # reattch the raw image file since macOS doesn't have a partprobe...
-        # this is the only way I know to get macOS to reprobe the disk
-        hdiutil eject $ld
-        unset ld_path
-        unset ld
-        unset ld_path_raw
-
-        ld_path_raw=$(hdiutil attach -readwrite -imagekey diskimage-class=CRawDiskImage -nomount -blocksize 512 -noverify /tmp/disk.img)
-        ld=$(echo $ld_path_raw | grep "FDisk_partition_scheme" | awk '{print $1}' | sed s:/dev/::)
-        ld_path="/dev/$ld"
-
-        if ! [ -b /dev/$ld ]; then
-            echo "Unable to remount disk! exitting before I do some damage!"
-            exit 5
-        fi
-
-        # get first partition and format as FAT32
-        firstpart=$(diskutil list $ld | grep 1: | awk '{print $6}')
-        firstpart_direct="r$firstpart"
-
-        newfs_msdos -F 32 /dev/$firstpart_direct
-        sync
-        
-        # copy MBR while preserving partition table
-        dd if=$mbr_file of=$ld_path bs=1 count=440 conv=sync
-        # copy MBR 0xAA55
-        dd if=$mbr_file of=$ld_path bs=1 seek=510 skip=510 count=2 conv=sync
-
-        # copy VBR to partition 1 while preserving partition information
-        # copy jmp short entry; nop
-        dd if=$vbr_file of=/dev/$firstpart bs=1 count=3 conv=sync
-        # copy bootcode
-        dd if=$vbr_file of=/dev/$firstpart bs=1 seek=90 skip=90 count=420 conv=sync
-        # copy 0xAA55
-        dd if=$vbr_file of=/dev/$firstpart bs=1 seek=510 skip=510 count=2 conv=sync
-
-        #stage2 to sectors 1-64
-        dd if=$stage2_file of=$ld_path bs=$disk_sector_size seek=1 conv=sync
-
-        #sync pending dd stuff
-        sync
-
-        # copy boot32 boot test file to disk image
-        if ! [ -e $mount_point ]; then
-            mkdir $mount_point
-        else
-            echo "$mount_point exists! clearing contents..."
-            rm -rfv $mount_point
-            mkdir $mount_point
-        fi
-        mount -t msdos /dev/$firstpart $mount_point
-
-        if [ -e $boottest_file ]; then
-            cp -v $boottest_file $mount_point
-        else
-            echo "unable to find boot32.bin!"
-            exit 3
-        fi
-
-        # detach loop device
-        sync
-        umount /dev/$firstpart
-        hdiutil eject $ld
-
-        # chown to the real user to prevent issues with reading/writing the file later
-        SUDOUSER=$(logname)
-        chown ${SUDOUSER}:staff disk.img
-        gzip -9kc $disk_tmp_file > $disk_file_final
-    else
-        echo "unable to find MBR/VBR binaries!"
-        exit 2
+        dd if=$vbr_file of="$part_img" bs=1 seek=90 skip=90 count=420 conv=notrunc
+        # copy signature (should be 0xAA55)
+        dd if=$vbr_file of="$part_img" bs=1 seek=510 skip=510 count=2 conv=notrunc
+
+        # copy backup VBR within the created partition image
+        # Linux dosfstools will complain (read: not work) unless this is done it seems
+        # HACK: sector 6 is the **default** location of the BPB_BkBootSec, it **can** be different.
+        dd if="$part_img" of="$part_img" bs=$disk_sector_size count=1 seek=6 conv=notrunc
+
+        echo "[5/7] Copy boot payload to FAT32 filesystem using mtools as BOOT.BIN"
+        MTOOLSRC="$mtool_src" mcopy "$boottest_file" C:BOOT.BIN
+        MTOOLSRC="$mtool_src" mdir C:
+
+        echo "[6/7] Patch MBR and install stage2 loader to disk image"
+        # patch MBR+signature while preserving partition table
+        dd if="$mbr_file" of="$disk_img" bs=1 count=440 conv=notrunc
+        dd if="$mbr_file" of="$disk_img" bs=1 seek=510 skip=510 count=2 conv=notrunc
+
+        # copy stage2 to absolute LBA 1
+        dd if="$stage2_file" of="$disk_img" bs=$disk_sector_size seek=1 conv=notrunc
+
+        echo "[7/7] Assembling final disk image"
+        # place partition at it's place in the disk image
+        dd if="$part_img" of="$disk_img" bs=$disk_sector_size seek=$part_start conv=notrunc
+
+        echo " *** Outputing disk images will be in ./build/output/* *** "
+        
+        if [ ! -d ./build/output ]; then
+            echo "./build/output does not exist. creating"
+            mkdir -p ./build/output
        fi
+        gzip -9c "$disk_img" > "$disk_img_final"
+        gzip -9c "$part_img" > "$part_img_final"
+        tar caf "$artifacts_archive" --exclude ./build/output ./build/ 
 else
        # Unknown.
-        echo "Unknown OS type! Supported build hosts systems are GNU/Linux (WSL) and macOS."
+        echo "Unknown OS type! Supported build hosts systems are GNU/Linux (& WSL)"
        exit 1
 fi
--- a/scripts/loop_setup.sfdisk
+++ b/scripts/loop_setup.sfdisk
@@ -1,5 +0,0 @@
-label: dos
-unit: sectors
-sector-size: 512
-
-start=        2048, type=c, bootable
--- a/src/mbr/mbr.nasm
+++ b/src/mbr/mbr.nasm
@@ -14,11 +14,11 @@
 ;     along with this program.  If not, see <https://www.gnu.org/licenses/>.

 [BITS 16]
-[ORG 0x8C00]
+[ORG 0x6C00]
 [CPU KATMAI]
 [WARNING -reloc-abs-byte]
 [WARNING -reloc-abs-word]                   ; Yes, we use absolute addresses. surpress these warnings.
-[map all mbr.map]
+[map all build/mbr.map]
 %define __STEVIA_MBR
 jmp short (init - $$)
 nop
@@ -33,10 +33,10 @@ nop
 %include "config.inc"
 %include "error_codes.inc"
 %include "partition_table.inc"
-%include "fat32/fat32_structures.inc"

 %undef __STEVIA_DEV_DEBUG

+; BIOS will load 1st sector of boot drive to 0x7c00, init and relocate
 ALIGN 4
 init:
    cli                             ; We do not want to be interrupted
@@ -58,14 +58,14 @@ init:
    cld
    rep stosb                         ; zero bss section

-    sub sp, 0x20                    ; local varible space
+    sub sp, 0x10                    ; local varible space (32 bytes)
    push bp                         ; setup top of stack frame

    xor cx, cx
    mov ch, 0x02                    ; 0x0200 in cx
    mov si, 0x7C00                  ; Current MBR Address (loaded here by BIOS)
    mov di, MBR_ENTRY               ; New MBR Address (our new relocation address)
-    rep movsb                       ; copy 512 bytes from 0x0000:7c00 to 0x0000:MBR_ENTRY (7A00 as of writing)
+    rep movsb                       ; copy 512 bytes from 0x0000:7c00 to 0x0000:MBR_ENTRY (6C00 as of writing)

    sti

@@ -96,6 +96,8 @@ main:
        mov ah, 0x41
        mov bx, 0x55AA
        mov dl, 0x80
+
+        clc
        int 0x13
        jnc main.find_active
        ERROR MBR_ERROR_NO_INT32E                         ; no extended function support
@@ -107,7 +109,7 @@ main:
        mov al, byte [bx + PartEntry_t.attributes]
        test al, 0x80                           ; 0x80 == 1000_0000b
        jnz main.active_found
-        add bx, 0x10                            ; add 16 bytes to offset
+        add bx, PartEntry_t_size                ; add 16 bytes to offset
        loop main.find_active_L0

        ERROR MBR_ERROR_NO_NO_BOOT_PART
@@ -119,42 +121,26 @@ main:
        mov word [bp - 4], ax                   ; update part_offset
    .read_data:
        movzx ax, byte [bp - 2]
-        push ax                                            ; drive_num
-
-        mov ax, 0x1
-        push ax                                            ; count
+        push ax                                            ; drive_num (2)
+        push 0x01                                          ; count (2)

        mov dword eax, dword [bx + PartEntry_t.lba_start]
-        push dword eax                                     ; lba
+        push dword eax                                     ; lba (4)

-        mov ax, VBR_ENTRY
-        push ax                                            ; offset = 0x7c00
-
-        xor ax, ax
-        push ax                                            ; segment = 0
+        push word 0x7C00                                   ; offset = 0x7c00 (2)
+        push 0x00                                          ; segment = 0 (2)

        ; uint8_t read_stage2_raw(uint16_t buf_segment, uint16_t buf_offset, 
        ;                         uint32_t lba,
        ;                         uint16_t count, uint16_t drive_num)
-        call read_disk_raw
+        call BIOS_int13h_ext_read
        add sp, 0xC
    .goto_vbr:
        cmp word [VBR_ENTRY + 0x1FE], 0xAA55
        je main.sig_ok
        ERROR MBR_ERROR_NO_VBR_SIG              ; no signature present
    .sig_ok:  
-        mov ax, PartTable_t_size                
-        push ax
-        mov ax, DiskSig                         ; start of partition table
-        push ax
-        mov ax, partition_table                 
-        push ax
-        call kmemcpy                            ; copy partition table to bss
-        add sp, 0x6
-        
-        mov si, word [bp - 4]
-        mov dl, byte [bp - 2]
-        mov bx, partition_table
+        mov dl, byte [bp - 2]                   ; pass drive # from BIOS to VBR in dl
        jmp word 0x0000:VBR_ENTRY

 ; ###############
@@ -183,18 +169,15 @@ PartEntry4:
    times 16 db 0x00
 BootSig:
    dw 0xAA55                    ; Add boot signature at the end of bootloader
-
+; !!! end of MBR !!!
 section .bss follows=.text
 begin_bss:

-align 16, resb 1
-partition_table resb PartTable_t_size
-
 align 16, resb 1
 lba_packet resb LBAPkt_t_size

 align 512, resb 1
-stack_bottom resb 512                  ; 512 byte stack early on
+stack_bottom resb 1024 - 16                 ; 512 byte stack early on
 stack_top:
-mbr_redzone resb 32
+mbr_redzone resb 16
 end_bss:
--- a/src/stage2/stage2.nasm
+++ b/src/stage2/stage2.nasm
@@ -15,8 +15,8 @@

 [BITS 16]
 [ORG 0x0500]                            ; IF YOU CHANGE ORG CHANGE THE SIGN OFFSET AT THE END
-[CPU KATMAI]
-[map all stage2.map]
+[CPU 686]
+[map all build/stage2.map]
 [WARNING -reloc-abs-byte]
 [WARNING -reloc-abs-word]
 [WARNING -reloc-abs-dword]              ; Yes, we use absolute addresses. surpress these warnings.
@@ -31,31 +31,15 @@
 %include "cdecl16.inc"
 %include "entry.inc"
 %include "config.inc"
-%include "early_mem.inc"
 %include "error_codes.inc"

-%macro print_string 1
-    mov ax, %1
-    push ax
-    call PrintString
-    add sp, 0x2
-%endmacro
-
 section .text
 begin_text:
 ; dl = byte boot_drive
-; ax = word part_offset (active partition offset)
-; si = ptr PartTable_t partition_table
-; di = ptr FAT32_bpb_t fat32_bpb
-ALIGN 4, db 0x90
+ALIGN 16, db 0x90
 init:
    cli                               ; We do not want to be interrupted
-
-    ; these 4 are stored in the .data section and are effectivly const types
-    mov [vbr_part_table_ptr], si             ; pointer to partition_table
-    mov [vbr_fat32_bpb_ptr], di              ; pointer to fat32_bpb
-    mov [boot_drive], dl                     ; copy boot_drive to globals
-    mov [partition_offset], ax               ; copy partition_offset to globals
+    mov [u8_BootDrive], dl              ; copy boot_drive to globals

    mov ax, __STAGE2_SEGMENT          ; set all our segments to the configured segment, except es
    mov ds, ax                        ; *
@@ -88,7 +72,7 @@ init:
    jmp word __STAGE2_SEGMENT:main

 ; ###############
-; Functions
+; Core Functions
 ; ###############

 %include "util/kmem_func.nasm"
@@ -96,11 +80,18 @@ init:
 %include "util/kmemset4_func.nasm"
 %include "util/error_func.nasm"

+; ###############
+; Functions
+; ###############
+%include "util/arena_alloc.nasm"
+
 ; ###############
 ; FAT32 Driver
 ; ###############

-%include 'fat32/FAT32_SYS.inc'
+%include "partition_table.inc"
+%include "fat32/fat32_structures.inc"
+%include 'fat32/FAT32_SYS.nasm'

 ; ###############
 ; BIOS functions
@@ -111,14 +102,10 @@ init:
 ; structures

 struc SteviaInfoStruct_t
-    .MemoryMapPtr      resd 1
-    .MemoryMapEntries  resd 1
-endstruc
-
-struc EarlyBootStruct_t
-    .partition_table resb PartTable_t_size
-    .fat32_bpb       resb FAT32_bpb_t_size
-    .fat32_ebpb      resb FAT32_ebpb_t_size
+    .p16_E820MemoryMapPtr       resw 1
+    .u16_E820MMapEntryCount     resw 1
+    .p16_MbrPtr                 resw 1
+    .p16_VbrPtr                 resw 1
 endstruc

 ALIGN 4, db 0x90
@@ -130,55 +117,71 @@ main:
    je main.stage2_main
    ERROR STAGE2_SIGNATURE_MISSING
 .stage2_main:
-    mov ax, PartTable_t_size
-    push ax                                                 ; len = PartTable_t_size
-    mov ax, word [vbr_part_table_ptr]                       ; src = ptr to vbr partition_table
-    push ax
-    mov ax, partition_table                                 ; dst
-    push ax
-    call kmemcpy                                            ; copy partition table data to .data section in stage2
-    add sp, 0x6
-
-    mov ax, (FAT32_bpb_t_size + FAT32_ebpb_t_size)          ; len
-    push ax
-    mov ax, word [vbr_fat32_bpb_ptr]                        ; src            
-    push ax
-    mov ax, fat32_bpb                                       ; dst
-    push ax
-    call kmemcpy                                            ; copy bpb & ebpb to memory
-    add sp, 0x6
-
    call SetTextMode
-    call disable_cursor
-    print_string HelloPrompt_info
+    call disable_cursor_bios
+
+    ; setup the early heap
+    __CDECL16_CALL_ARGS early_heap_state
+    __CDECL16_CALL ArenaInit, 1
+
+    __CDECL16_CALL_ARGS pszHelloPrompt
+    __CDECL16_CALL PrintString, 1
+ 
+    ; setup heap space for mbr data
+    __CDECL16_CALL_ARGS 0x200, 0x10
+    __CDECL16_CALL ArenaAlloc, 2
+    mov word [SteviaInfo + SteviaInfoStruct_t.p16_MbrPtr], ax
+
+    push ax                                         ; dst
+    movzx ax, byte [u8_BootDrive]                     
+    push ax                                         ; boot_drive
+    __CDECL16_CALL FAT32_load_mbr, 2                ; fill/validate mbr buffer
+
+    ; setup heap space for vbr data
+    __CDECL16_CALL_ARGS 0x200, 0x10
+    __CDECL16_CALL ArenaAlloc, 2
+    mov word [SteviaInfo + SteviaInfoStruct_t.p16_VbrPtr], ax
+
+    push ax                                         ; dst
+    movzx ax, byte [u8_BootDrive]
+    push ax                                         ; boot_drive
+    __CDECL16_CALL FAT32_load_vbr, 2                ; fill/validate vbr buffer

    ; enable A20 gate
    call EnableA20
-    print_string A20_Enabled_OK_info
+    __CDECL16_CALL_ARGS pszA20EnabledOk
+    __CDECL16_CALL PrintString, 1

    ; get system memory map
    call GetMemoryMap
-    print_string MemoryMap_OK_info
+    __CDECL16_CALL_ARGS pszMemoryMapOk
+    __CDECL16_CALL PrintString, 1

-    ; enter unreal mode
+    ; enter unreal mode (enter PM w/ 16 bit code, 32 bit flat memory model & return to real)
+    ; ds, es will be set to the 64KiB STAGE2_SEGMENT, fs/gs will be flat/huge memory (4GiB)
+    ; use __REFLAT macros to re-flat ds/es for easy transfers to >1MiB
+    ; NOTE: if you modify a segment register you will need to re-unreal it
    call EnterUnrealMode
-    print_string UnrealMode_OK_info
+    __CDECL16_CALL_ARGS pszUnrealModeOk
+    __CDECL16_CALL PrintString, 1

    ; FAT Driver setup
-    call InitFATDriver
-    print_string InitFATSYS_OK_info
+    ;call InitFATDriver
+    ;__CDECL16_CALL_ARGS pszInitFAT32Ok
+    ;__CDECL16_CALL PrintString, 1

    ;
    ; Find first cluster of bootable file
-    call SearchFATDIR
-    push dword eax      ; save first cluster of bootable file
+    ;call SearchFATDIR
+    ;push dword eax      ; save first cluster of bootable file

-    print_string FileFound_OK_info
+    ;__CDECL16_CALL_ARGS pszFileFoundMsg
+    ;__CDECL16_CALL PrintString, 1

-    pop dword eax
-    push dword eax      ; print Cluster of boot file
-    call PrintDWORD     ; void PrintDWORD(uint32_t dword)
-    add sp, 0x4
+    ;pop dword eax
+    ;push dword eax      ; print Cluster of boot file
+    ;call PrintDWORD     ; void PrintDWORD(uint32_t dword)
+    ;add sp, 0x4

    ; TODO: using first cluster information, start loading the kernel to memory
    ; TODO: going to need an elf parser,  some unreal mode file buffer functions to move the data
@@ -187,171 +190,109 @@ hcf:

 ; ##############################
 ;
-; SYSTEM CONFIGURATION FUNCTIONS
+; SYSTEM CONFIGURATION FUNCTIONS & MACROS
 ;
 ; ##############################

-; Prints a C-Style string (null terminated) using BIOS vga teletype call
-; void PrintString(char* buf)
-ALIGN 4, db 0x90
-PrintString:
-    __CDECL16_ENTRY
-    mov di, [bp + 4]    ; first arg is char[] 
-.str_len:
-    xor cx, cx         ; ECX = 0
-    not cx             ; ECX = -1 == 0xFFFF
-    xor ax, ax         ; search for al = 0x0
+; set ds and es segments back to the base of the loader
+%ifnmacro __TINY_DS_ES
+%macro __TINY_DS_ES 0
+    mov ax, __STAGE2_SEGMENT
+    mov ds, ax
+    mov es, ax
+%endmacro
+%endif

-    cld
-    repne scasb        ; deincrement cx while searching for al
-
-    not cx             ; the inverse of a neg number = abs(x) - 1
-    dec cx             ; CX contains the length of the string - nul byte at end
-.print:
-    mov si, [bp + 4]            ; source string
-.print_L0:
-    movzx ax, byte [si]
-    push ax
-    call PrintCharacter
-    add sp, 0x2
-
-    inc si
-    dec cx
-
-    jcxz PrintString.endp
-    jmp PrintString.print_L0    ; Fetch next character from string
-.endp:
-    __CDECL16_EXIT
-    ret                         ; Return from procedure
-
-; Prints a single character
-; void PrintCharacter(char c);
-ALIGN 4, db 0x90
-PrintCharacter:
-    __CDECL16_ENTRY
-.func:
-    movzx ax, byte [bp + 4]     ; AL = character c
-    mov ah, 0x0E                ; INT 0x10, AH=0x0E call
-    mov bx, 0x0007              ; BH = page no. BL =Text attribute 0x07 is lightgrey font on black background
-    int 0x10                    ; call video interrupt
-.endp:
-    __CDECL16_EXIT
-    ret
-
-; TODO: fix the prolog, epilog and stack usage to confirm with cdecl16
-; prints the hex representation of of val
-; void PrintDWORD(uint32_t val);
-ALIGN 4, db 0x90
-PrintDWORD:
-    __CDECL16_ENTRY
-.func: 
-    mov si, IntToHex_table
-    mov ebx, 16     ; base-16
-
-    mov eax, dword [bp + 4]     ;val
-
-    xor edx, edx
-    xor cx, cx
-.next_digit:
-    div ebx            ; dividend in edx:eax -> quotient in eax, remainder in edx
-    push dx            ; save remainder
-    inc cx
-
-    xor dx, dx
-    test eax, eax
-    jnz PrintDWORD.next_digit
-
-.zero_pad:
-    cmp cx, 0x0008
-    je PrintDWORD.print_stack
-    xor ax, ax
-    push ax
-    inc cx
-    jmp PrintDWORD.zero_pad
-
-.print_stack:
-    pop bx
-    dec cx
-    push cx
-
-    movzx ax, byte [bx+si+0]    ; bx = index into Hex lookup table
-    push ax
-    call PrintCharacter
-    add sp, 0x2
-
-    pop cx
-
-    jcxz PrintDWORD.endp
-    jmp PrintDWORD.print_stack
-
-.endp:
-    __CDECL16_EXIT
-    ret
-
-; ##############################
-;
-; SYSTEM CONFIGURATION FUNCTIONS
-;
-; ##############################
-ALIGN 4, db 0x90
-EnterUnrealMode:
-    __CDECL16_ENTRY
-.func:
+; for copying between locations in high memory
+%ifnmacro __REFLAT_DS_ES
+%macro __REFLAT_DS_ES 0
    cli                                   ; no interrupts   
-    push ds                     ; save real mode data/stack selectors
-    push es
-    push fs
-    push gs
-    push ss
-
-    push cs                               ; save real mode code selector
-    xor ax, ax                            ;
-    pop ax                                ; save cs to ax to setup far jump
-    mov word [__UNREAL_SEGMENT], ax    
-
-    lgdt [((__STAGE2_SEGMENT << 4) + unreal_gdt_info)]                 ; load unreal gdt
+    lgdt [((__STAGE2_SEGMENT << 4) + UnrealGdtInfo)]                 ; load unreal gdt

    mov eax, cr0                          
-    or al,1                               ; set pmode bit
+    or eax, 1                             ; set pmode bit
    mov cr0, eax                          ; switch to pmode
-    jmp short $+2
+    jmp short $+2                         ; i-cache flush

-    ;jmp far 0x0008:EnterUnrealMode.load_cs
-    db 0xEA                               ; jmp far imm16:imm16
-    dw EnterUnrealMode.load_cs            ; error_far_ptr
-    dw 0x0008                             ; error_far_seg
-.load_cs:
-    mov bx, 0x10                          ; select descriptor 2
-    mov ds, bx                            ; 10h = 0001_0000b
+    mov ax, 0x10                          ; select descriptor 2
+    mov ds, ax
+    mov es, ax               

-    mov ss, bx
-    mov es, bx
-    mov fs, bx
-    mov gs, bx                            ; other data/stack to index 2 (off 0x10)
-    
-    and al,0xFE                           ; toggle bit 1 of cr0
+    mov eax, cr0
+    and eax, ~1                           ; toggle bit 1 of cr0
    mov cr0, eax                          ; back to realmode
-    jmp short $+2
-    
-    ;jmp far 0x0008:EnterUnrealMode.unload_cs
-    db 0xEA                               ; jmp far imm16:imm16
-    dw EnterUnrealMode.unload_cs          ; error_far_ptr
-__UNREAL_SEGMENT:
-    dw 0x0000                             ; error_far_seg
-EnterUnrealMode.unload_cs:
-    pop ss
-    pop gs
-    pop fs
-    pop es
-    pop ds                                ; get back old segments
+    jmp short $+2                         ; i-cache flush
    sti
+
+%endmacro
+%endif
+
+; for copying from low memory to high memory (ds on a real segment, es in flat mode)
+%ifnmacro __REFLAT_ES
+%macro __REFLAT_ES 0
+    cli                                   ; no interrupts   
+    lgdt [((__STAGE2_SEGMENT << 4) + UnrealGdtInfo)]                 ; load unreal gdt
+
+    mov eax, cr0                          
+    or eax, 1                             ; set pmode bit
+    mov cr0, eax                          ; switch to pmode
+    jmp short $+2                         ; i-cache flush
+
+    mov ax, 0x10                          ; select descriptor 2
+    mov es, ax                            
+
+    mov eax, cr0
+    and eax, ~1                           ; toggle bit 1 of cr0
+    mov cr0, eax                          ; back to realmode
+    jmp short $+2                         ; i-cache flush
+    sti
+
+%endmacro
+%endif
+
+ALIGN 4, db 0x90
+EnterUnrealMode:
+    __CDECL16_PROC_ENTRY
+    cli                                   ; no interrupts
+.proc:    
+    lgdt [((__STAGE2_SEGMENT << 4) + UnrealGdtInfo)]                 ; load unreal gdt
+
+    mov eax, cr0                          
+    or eax, 1                             ; set pmode bit
+    mov cr0, eax                          ; switch to pmode
+
+    ; set cs to a pm code segment (0x8) w/ the following
+    jmp 0x0008:EnterUnrealMode.set_segs
+.set_segs:
+    mov ax, 0x10                          ; select descriptor 2
+    mov ds, ax                            ; 10h = 0001_0000b
+    mov es, ax                            ; es to big data
+
+    mov fs, ax
+    mov gs, ax                            ; extra segments to big data as well
+.pm_start:
+    ; code here is running in protected mode w/ descriptor 0x8
+    ; insert any PM test code needed here
+.pm_end:
+    mov eax, cr0
+    and eax, ~1                           ; toggle bit 1 of cr0
+    mov cr0, eax                          ; back to realmode
+    jmp __STAGE2_SEGMENT:EnterUnrealMode.endp
 .endp:
-    __CDECL16_EXIT
+    sti                                   ; re-enable interupts
+
+    ; set ds, es to the STAGE2_SEGMENT, for our model (generally) ds == es == cs
+    ; fs, gs & ss are all still huge data model, and the macro(s) "__REFLAT_xxx" exists
+    ; to easily access data outside of 64KiB boundries using ds/es addressing
+    __TINY_DS_ES
+
+    __CDECL16_PROC_EXIT
    ret
 end_text:

 section .data follows=.text
-align 512
+align 16, db 0
+
 begin_data:
 ; #############
 ;
@@ -360,90 +301,70 @@ begin_data:
 ; #############
 %define CRLF 0Dh, 0Ah

-%macro define_cstr 2
-    ALIGN 16
-    %1_cstr:
+%macro define_cstr 2-*
+%if %0 > 2
+    align 16
+    %1:
+        db %{2:-1}, 00h
+%else
+    align 16
+    %1:
        db %2, 00h
+%endif
 %endmacro

-%macro define_info 2
-    ALIGN 16
-    %1_info:
-        db %2, CRLF, 00h
-%endmacro
+define_cstr pszHelloPrompt, "Hello from Stevia Stage2!", CRLF
+define_cstr pszA20EnabledOk, "A20 Enabled OK", CRLF
+define_cstr pszMemoryMapOk, "Memory map OK", CRLF
+define_cstr pszUnrealModeOk, "Unreal mode OK", CRLF
+define_cstr pszInitFAT32Ok, "FAT32 Driver Init OK", CRLF

-define_info HelloPrompt, "Hello from Stevia Stage2!"
-define_info A20_Enabled_OK, "A20 Enabled OK"
-define_info MemoryMap_OK, "Memory map OK"
-define_info UnrealMode_OK, "Unreal mode OK"
-define_info FileFound_OK, "Found SFN entry for bootable binary, first cluster -> "
-define_info InitFATSYS_OK, "FAT32 Driver Init..."
-
-define_info SearchFATDIR, "Searching FAT DIR for bootable file..."
-define_info NextFATCluster, "Attempting to find next FAT cluster..."
-define_info ReadFATCluster, "Attempting to load next FAT"
-define_info MaybeFound_Boot, "Maybe found a file...checking..."
+define_cstr pszFileFoundMsg, "Found SFN entry for bootable binary, first cluster -> ", CRLF
+define_cstr pszSearchFAT32DirMsg, "Searching FAT fs for bootable file...", CRLF
+define_cstr pszReadFAT32ClusterMsg, "Attempting to load next FAT", CRLF
+define_cstr pszMaybeFoundBootMsg, "Maybe found a file...checking...", CRLF

 define_cstr BootTarget, "BOOT    BIN"

-ALIGN 16, db 0
-BootTarget:
-    db 'BOOT    BIN'
-
-;
-; pre-bss init globals (generally const...but there are exceptions)
-;
-
-align 8, db 0x00
-boot_drive:
+; set to boot_drive passed from BIOS almost first thing in init
+align 4, db 0
+u8_BootDrive:
    db 0x00

-align 8, db 0x00
-partition_offset:
-    dw 0x0000
-
-align 8, db 0x00
-vbr_fat32_bpb_ptr:
-    dw 0x0000
-
-align 8, db 0x00
-vbr_part_table_ptr:
-    dw 0x0000
-
-ALIGN 16
+align 16, db 0
 IntToHex_table:
    db '0123456789ABCDEF'

 ; see docs/gdt.txt for a quick refresher on GDT 
-ALIGN 16, db 0
-unreal_gdt_info:
-    unreal_gdt_size: dw (unreal_gdt_end - unreal_gdt_start) - 1
-    unreal_gdt_ptr:  dd ((__STAGE2_SEGMENT << 4) + unreal_gdt_start)
-unreal_gdt_start:
+align 16, db 0
+UnrealGdtInfo:
+    u16_UnrealGdt_size: dw (UnrealGdtEnd - UnrealGdtStart) - 1
+    pF_UnrealGdtPtr:  dd ((__STAGE2_SEGMENT << 4) + UnrealGdtStart)
+UnrealGdtStart:
    ; entry 0 (null descriptor)
    dq 0                    ; first entry is null

-    ; entry 1 (16bit code 64KiB limit)
+    ; entry 1 (0x8) (16bit code 64KiB limit)
    dd 0x0000FFFF        ; Base Address(15:0) 31:16, Segment Limit(15:0) 15:0
    db 0x00              ; Base Address 23:16
    db 1001_1010b        ; Access Byte: Present, ring0, S = 1, executable (1), non-conforming, readable, Accessed
    db 0000_0000b        ; Flags: GR = 4KiB, attr = <DB/L/Avl>, Granularity = 4KiB & 16:19 of limit
    db 0x00              ; Base Address 31:24

-    ; entry 2 (16bit data segment with 4 GiB flat mapping)
+    ; entry 2 (0x10) (16bit data segment with 4 GiB flat mapping)
    dd 0x0000FFFF        ; Base Address(15:0) 31:16, Segment Limit(15:0) 15:0
    db 0x00              ; Base Address(23:16)
    db 1001_0010b        ; Access Byte: Present, ring0, S = 1, data (0), non-confirming, writable, present
    db 1000_1111b        ; Flags: GR = 4KiB, attr = <16-bit/?/?>, Granularity = 4KiB & 16:19 of limit
    db 0x00              ; Base Address(31:24)
-unreal_gdt_end:
+UnrealGdtEnd:

-ALIGN 16, db 0
-gdt32_info:
-    gdt32_size: dw (gdt32_end - gdt32_start) - 1
-    gdt32_ptr:  dd ((__STAGE2_SEGMENT << 4) + gdt32_start)
-gdt32_start:
-    dq 0
+align 16, db 0
+Gdt32Info:
+    gdt32_size: dw (Gdt32End - Gdt32Start) - 1
+    gdt32_ptr:  dd ((__STAGE2_SEGMENT << 4) + Gdt32Start)
+Gdt32Start:
+        dq 0            ; null segment
    .gdt32_code:
        dw 0xFFFF       ; code segment (RX)
        dw 0x0000
@@ -472,82 +393,79 @@ gdt32_start:
        db 1001_0000b    ; Access: readable, not writable
        db 1100_1111b    ; 4KB granularity, 32-bit
        db 0x00
-gdt32_end:
+Gdt32End:

-ALIGN 8,db 0x00
-BUILD_NASM_VER:
+align 16,db 0
+BuildNasmVer:
    db "Stevia Stage2 built with NASM - ", __NASM_VER__, 00h

-ALIGN 8,db 0x00
-BUILD_DATETIME:
+align 16,db 0
+BuildDateTime:
    db 'Assembled - ', __DATE__, ' ', __TIME__, 00h

-ALIGN 8,db 0x00
-BUILD_GIT_VER:
+align 16,db 0
+BuildGitVer:
    db __GIT_VER__, 00h

-ALIGN 8,db 0x00
-BUILD_GIT_HASH:
+align 16,db 0
+BuildGitHash:
    db __GIT_HASH__, 00h
 end_data:

-%assign bytes_remaining ((MAX_STAGE2_BYTES - 4) - (($ - $$) + (end_text - begin_text)))
-%warning STAGE2 has bytes_remaining bytes remaining for code/data (MAX: MAX_STAGE2_BYTES)
+%define SIG_BYTES 0x4
+
+; Optional: fail fast if we overflowed
+%if ((MAX_STAGE2_BYTES - 512) - (($ - $$) + (end_text - begin_text))) < 0
+    %error "Stage2 overflow: code+data exceed MAX_STAGE2_BYTES - SIG_BYTES"
+%endif

 ; section start location needs to be a 'critical expression'
-; i.e resolvable at build time, we are setting 0x7E00 as the offset since
+; i.e resolvable at build time, we are setting 0x0500 as the offset since
 section .sign start=((MAX_STAGE2_BYTES - 512) + 0x0500)
 times ((512 - 4) - ($ -$$) ) db 0x90     ; nop
 STAGE2_SIG: dd 0xDEADBEEF                ; Signature to mark the end of the stage2
-
+; !!! END Stage2 .text/.data !!!
+align 16, resb 1
 section .bss follows=.sign
 begin_bss:
+
 ; structures
-
-align 8, resb 1
-partition_table resb PartTable_t_size
-
-align 8, resb 1
-fat32_bpb resb FAT32_bpb_t_size
-fat32_ebpb resb FAT32_ebpb_t_size
-
-align 8, resb 1
-fat32_nc_data resb 16
-
-align 8, resb 1
-lba_packet resb LBAPkt_t_size
-
-align 8, resb 1
-fat32_state:
-    resb FAT32_State_t_size
-
-align 8, resb 1
+align 16, resb 1
 SteviaInfo:
-    resd 4
-;
-; post-bss init globals
-;
+    resd SteviaInfoStruct_t_size
+
+align 16, resb 1
+early_heap_state:
+    resb ArenaStateStruc_t_size
+
+align 16, resb 1
+lba_packet: 
+    resb LBAPkt_t_size

 ;
 ; large continuous allocations
 ;
-align 16, resb 1
-disk_buffer:
-    resb 512
-fat_buffer:
-    resb 512
-dir_buffer:
-    resb 512
-fat_fsinfo:
-    resb 512

+; TODO: this will hold 42 entries from the map function
+; the e820 function needs to check that it doesn't overflow
+; but realisticly 42 entries is enough for dev work
 align 16, resb 1
-%define BIOSMemoryMap_SIZE 2048
+%define BIOSMemoryMap_SIZE 1024
 BIOSMemoryMap:
-    resb 2048
-
-align 512, resb 1
-stack_bottom:
-    resb 1024
-stack_top:
+    resb BIOSMemoryMap_SIZE
 end_bss:
+; !!! End bss data !!!
+%define STACK_SIZE 0x1000       ; 4 KiB
+
+; Pad to the cap (emits nothing in the file; only increases .bss virtual size).
+; If BSS_SIZE > BSS_MAX_BYTES, this becomes negative and NASM errors out.
+%define BSS_MAX_BYTES (0x2000 - STACK_SIZE)
+resb (BSS_MAX_BYTES - (end_bss - begin_bss))
+
+align 16, resb 1
+stack_bottom:
+    resb STACK_SIZE
+stack_top:
+
+; Optional: keep a label for later math:
+bss_cap_end:
--- a/src/vbr/vbr.nasm
+++ b/src/vbr/vbr.nasm
@@ -17,18 +17,25 @@
 [CPU KATMAI]
 [WARNING -reloc-abs-byte]
 [WARNING -reloc-abs-word]
-[map all vbr.map]                   ; Yes, we use absolute addresses. surpress these warnings.
+[map all build/vbr.map]                   ; Yes, we use absolute addresses. surpress these warnings.
 %define __STEVIA_VBR
 section .text
 __ENTRY:
+    ; try to force encode a short jmp nop: i.e 0xEB 0x5A 0x90
+    ; will jump right 0x5A (90 bytes) after the end of the ebpb
+    ; this could also be encoded as 0xE9 0x?? 0x?? for a near jump
+    ; if init ends up being >= 128 bytes from entry.
    jmp short (init - $$)
    nop

-; fill BPB area with 0x00 since we skip writing this part to disk
-; but we need it for the 'jmp short entry; nop' above
-times 33 db 0x00
+; 8 ascii bytes, "MSWIN 4.1", ""
+phy_bs_ident:
+times 8 db 0x00
+
+phy_bpb_start:
+times 25 db 0x00
+
 phy_ebpb_start:
-; fill eBPB area with 0x00 since we skip writing this part to disk
 times 54 db 0x00

 ; ###############
@@ -41,7 +48,6 @@ times 54 db 0x00
 %include "cdecl16.inc"
 %include "entry.inc"
 %include "config.inc"
-%include "early_mem.inc"
 %include "error_codes.inc"
 %include "partition_table.inc"
 %include "fat32/fat32_structures.inc"
@@ -72,7 +78,7 @@ init:
    cld
    rep stosb                          
    
-    sub sp, 0x20                    ; local varible space
+    sub sp, 0x10                    ; local varible space (32 bytes)
    push bp

    sti                             ; all done with inital setup and relocation, reenable interupts
@@ -86,10 +92,6 @@ init:
 %include "util/kmem_func.nasm"
 %include "util/error_func.nasm"

-; ###############
-; End Section
-; ###############
-
 ;
 ; byte boot_drive @ bp - 2
 ; word part_offset @ bp - 4
@@ -97,31 +99,9 @@ init:
 ALIGN 4, db 0x90
 main:
    mov byte [bp - 2], dl                                  ; boot_drive
-    mov word [bp - 4], si                 ; part_offset
-    mov word [bp - 6], bx                 ; partition_table
-
-.load_fs_data:
-    mov ax, PartTable_t_size                           ; count=
-    push ax                                             
-    mov ax, [bp - 6]                                   ; src= ptr partition_table
-    push ax
-    mov ax, partition_table                            ; dst=      
-    push ax
-    call kmemcpy                                       ; copy partition table data
-    add sp, 0x6
-
-    mov ax, (FAT32_bpb_t_size + FAT32_ebpb_t_size)     ; size in byte, should be 90 bytes
-    push ax
-    mov ax, __ENTRY                                    
-    push ax
-    mov ax, fat32_bpb                                  ; 
-    push ax
-    call kmemcpy                                       ; copy bpb & ebpb to memory
-    add sp, 0x6
-
 .check_FAT_size:                                           ; we only support a very specific setup of FAT32
-    mov bx, fat32_bpb
-    test word [bx + FAT32_bpb_t.unused2_ZERO_word], 0      ; TotSectors16 will not be set if FAT32
+    mov bx, phy_bpb_start
+    test word [bx + FAT32_bpb_t.u16_TotalSectors16], 0      ; TotSectors16 will not be set if FAT32
    jz main.load_stage2
    ERROR VBR_ERROR_WRONG_FAT_SIZE
 .load_stage2:
@@ -129,28 +109,21 @@ main:
    movzx ax, byte [bp - 2]
    push ax                                            ; drive_num

-    mov ax, STAGE2_SECTOR_COUNT
-    push ax                                            ; count
+    push STAGE2_SECTOR_COUNT                           ; count

    mov dword eax, 0x1
    push dword eax                                     ; lba

-    mov ax, STAGE2_ENTRY
-    push ax                                            ; offset
-
-    xor ax, ax
-    push ax                                            ; segment = 0
+    push STAGE2_ENTRY                                  ; offset
+    push 0x00                                          ; segment = 0

    ; uint8_t read_stage2_raw(uint16_t buf_segment, uint16_t buf_offset, 
    ;                         uint32_t lba,
    ;                         uint16_t count, uint16_t drive_num)
-    call read_disk_raw
+    call BIOS_int13h_ext_read
    add sp, 0xC
 .enter_stage2:
    mov dl, byte [bp - 2]                ; byte boot_drive
-    mov ax, word [bp - 4]               ; word part_offset
-    mov si, partition_table             ; ptr partition_table
-    mov di, fat32_bpb                   ; ptr fat32_bpb
    jmp word 0x0000:STAGE2_ENTRY

 ; ###############
@@ -166,25 +139,16 @@ times (510 - ($ - $$)) nop     ; Fill the rest of sector with nop

 BootSig:
    dw 0xAA55                    ; Add boot signature at the end of bootloader
+; !!! END VBR !!!

 section .bss follows=.text
 begin_bss:

-align 16, resb 1
-partition_table resb PartTable_t_size
-
-align 16, resb 1
-fat32_bpb resb FAT32_bpb_t_size
-fat32_ebpb resb FAT32_ebpb_t_size
-
-align 16, resb 1
-fat32_nc_data resb 16
-
 align 16, resb 1
 lba_packet resb LBAPkt_t_size

 align 512, resb 1
-stack_bottom resb 512                  ; 512b stack early on
+stack_bottom resb (1024 - 16)                  ; 512b stack early on
 stack_top:
-vbr_redzone resb 32
+vbr_redzone resb 16
 end_bss:
Author	SHA1	Message	Date
Elaina Claus	4a944bc493	minor changes in fat32	2025-09-20 08:29:43 -04:00
Elaina Claus	137735431a	move stack after bss padding	2025-09-18 19:16:27 -04:00
Elaina Claus	6caaf6aa6d	some structures for okteta put in $(qtpaths --paths GenericDataLocation)	2025-09-18 17:20:17 -04:00
Elaina Claus	1e9de446f0	a few fixes to complete the move	2025-09-18 14:25:27 -04:00
Elaina Claus	5f2ca55af7	move mbr/vbr code to FAT32 system	2025-09-18 14:19:39 -04:00
Elaina Claus	11656c2827	more error codes and checks in vbr	2025-09-18 14:07:45 -04:00
Elaina Claus	f87f88a0dc	fix qemu launch	2025-09-18 14:06:52 -04:00
Elaina Claus	7baa53178a	update gitignore	2025-09-18 14:06:32 -04:00
Elaina Claus	8002d1cb54	more fat fs type checks	2025-09-18 11:50:27 -04:00
Elaina Claus	d8a89cfd2b	remove shortjmp and ident from bpb	2025-09-18 11:20:05 -04:00
Nivirx	6c402b5c4f	update structures	2025-09-17 21:48:37 -04:00
Elaina Claus	a3c9897291	prototyping	2025-09-17 20:59:48 -04:00
Elaina Claus	831d45c33c	rename ext_disk_read to BIOS_int13h_ext_read	2025-09-17 18:54:59 -04:00
Elaina Claus	918e94689f	2KiB stack	2025-09-17 18:44:55 -04:00
Elaina Claus	8d2cde0a31	added no planned fat32 error codes and added mbr/vbr reading error codes	2025-09-17 17:02:08 -04:00
Elaina Claus	8d3788a76e	remove unused structure	2025-09-17 16:50:59 -04:00
Elaina Claus	4a27e09872	use partition entry size constant	2025-09-17 16:24:45 -04:00
Elaina Claus	59bc1afb7c	stick mmap info in SteviaInfo	2025-09-17 16:24:27 -04:00
Elaina Claus	8b0b73d8a4	start partition table at entry 1	2025-09-17 16:22:47 -04:00
Elaina Claus	803be58c10	Merge branch 'trunk' into fat_v2	2025-09-16 08:36:46 -04:00
Elaina Claus	528e3d69fe	update github workflow since github includes firefox & snaps in the default runner image, which causes the build to fail. All checks were successful Daily Build and trunk tester / debian_update (push) Successful in 1m11s Details going to need a custom runner I guess...might as well only do actions on gitea.	2025-09-16 08:34:22 -04:00
Elaina Claus	51bd250925	minor corrections	2025-09-13 15:30:11 -04:00
Elaina Claus	460165a8d1	re-naming	2025-09-13 15:07:36 -04:00
Elaina Claus	935cbd1089	naming changes to ReadMbr/Vbr	2025-09-13 14:56:26 -04:00
Elaina Claus	7f1b4fa632	more naming changes	2025-09-13 14:51:30 -04:00
Elaina Claus	14f6788a22	renaming things to a hungarian style and adding "types"	2025-09-13 14:41:09 -04:00
Elaina Claus	526c3e7ea5	remove define_info macro, improved cstr macro and renamed all the OK/Msg debug strings	2025-09-13 13:45:37 -04:00
Elaina Claus	721ff2e62d	cap bss, clean up some padding issues and clean up sign section	2025-09-13 12:50:42 -04:00
Elaina Claus	a50af35abd	cleaned up memory maps and added a map for stage2	2025-09-13 12:48:19 -04:00
Elaina Claus	7cd6baa74d	added 2 proc's to read mbr/vbr to a buffer and setup some early ptr's to partition tables and the like	2025-09-12 23:16:04 -04:00
Elaina Claus	40fa4062ce	1KiB stack stage2 gets doesn't need extra information from the mbr/vbr now.	2025-09-12 23:13:57 -04:00
Elaina Claus	a8b24c7b01	add functions to get the mbr/vbr in stage2	2025-09-11 19:05:50 -04:00
Elaina Claus	58fc4a08dd	more me just reviewing the code base and comments	2025-09-11 17:33:08 -04:00
Elaina Claus	3da2af2d2d	add comments to args passed to vbr	2025-09-11 17:06:35 -04:00
Elaina Claus	75d77e92e1	🤔	2025-09-11 17:06:08 -04:00
Elaina Claus	8e6c823a00	modified: include/cdecl16.inc	2025-09-11 14:01:30 -04:00
Elaina Claus	fca8a5d573	update readme	2025-09-11 12:25:03 -04:00
Elaina Claus	f341a50b78	removed unused macro for calling read_disk_raw more simplification of push's	2025-09-11 12:12:48 -04:00
Elaina Claus	ef22bc9cd3	quick todo	2025-09-10 21:14:34 -04:00
Elaina Claus	507a05949f	account for .sign section in bytes_remaining calculation	2025-09-10 11:36:40 -04:00
Elaina Claus	caed66a243	don't relocate the MBR to the stage2 heap space this will save us disk reads for patition table info	2025-09-10 11:36:10 -04:00
Elaina Claus	d5cd8d6c45	remove unused early_mem.inc	2025-09-09 18:54:28 -04:00
Elaina Claus	b0f118b139	remove unused	2025-09-09 18:54:15 -04:00
Elaina Claus	71d50cdbd8	move the bpb_offset_bx file to old fat32	2025-09-09 18:50:34 -04:00
Elaina Claus	3c654b1be0	more rtfm'ing with encoding, 25 bytes of free code space in vbr now	2025-09-09 18:37:39 -04:00
Elaina Claus	0d90b3efd6	I rtfm'ed and saw there was a push m/16 encoding mbr now has 93 bytes free for more code	2025-09-09 18:25:24 -04:00
Elaina Claus	b08605f295	remove dep on fat32_structures	2025-09-09 17:47:17 -04:00
Elaina Claus	aa0efe5ff8	a bunch of planning for what the new FAT driver should probably look like.	2025-09-09 17:02:35 -04:00
Elaina Claus	700148a2f6	disable fat32 parts to keep the build...building	2025-09-09 17:01:44 -04:00
Elaina Claus	14ef0151ca	move old fat32 system to fat32/old	2025-09-09 17:01:14 -04:00
Elaina Claus	1d696371d2	updated QEMU args to match as close as possible to bochs	2025-09-09 17:00:41 -04:00
Elaina Claus	d30abe7a27	don't need to keep these dir's	2025-09-09 17:00:12 -04:00
Elaina Claus	d6f6076d45	don't need the directory here	2025-09-09 12:09:31 -04:00
Elaina Claus	4e05efaa6b	Big cleanup in Makefile to follow Makefile standards a bit better. minor edits to create-disk.sh to work with some of the changes for now	2025-09-09 11:03:50 -04:00
Elaina Claus	7cc0b4a392	first round of refactoring for the Makefile	2025-09-09 10:06:35 -04:00
Elaina Claus	9a6fea658d	bugs All checks were successful Daily Build and trunk tester / debian_update (push) Successful in 51s Details	2025-09-07 18:43:03 -04:00
Elaina Claus	891bff9509	use __CDECL16 macros and clean up a few proc calls	2025-09-07 17:38:21 -04:00
Elaina Claus	1e181bc22c	remove print_string macro	2025-09-07 16:25:08 -04:00
Elaina Claus	68c8200aa4	remove invoke macro for now	2025-09-07 16:21:19 -04:00
Elaina Claus	766c67c041	first calls to use the new cdecl16 macros	2025-09-07 16:11:18 -04:00
Elaina Claus	49d82be0e8	use rotate instead of stack context in macros	2025-09-07 16:10:59 -04:00
Elaina Claus	69bd7d8f56	small clean up and use configured segment for return to real mode	2025-09-07 14:50:40 -04:00
Elaina Claus	875527aa98	output to bochs magic debug port as well	2025-09-07 14:49:21 -04:00
Elaina Claus	c0d47d4db0	re-organize bochs config, added USB 1.0/1.1/2.0 and e1000 network	2025-09-07 14:48:35 -04:00
Elaina Claus	81a3442ac5	remove magic debug from unrealmode entry	2025-09-07 13:51:23 -04:00
Elaina Claus	3ec55f5a39	change some macro names to make them more clear	2025-09-07 13:33:26 -04:00
Elaina Claus	9493aefa68	rename __CDECL16_ENTRY and EXIT	2025-09-07 13:29:24 -04:00
Elaina Claus	6f2fc627be	new fancy macros to make it nicer to call functions	2025-09-07 13:16:37 -04:00
Elaina Claus	20c715fadd	update notes on unreal entry	2025-09-07 13:15:40 -04:00
Elaina Claus	920c623a93	update README.md All checks were successful Daily Build and trunk tester / debian_update (push) Successful in 1m5s Details	2025-09-06 13:56:00 -04:00
Elaina Claus	af8e7d74d3	I don't plan on using mmx/sse, set the minimum cpu to a 686	2025-09-06 13:55:45 -04:00
Elaina Claus	fde7abc544	replace or opcode with test test only updates flags	2025-09-06 08:38:16 -04:00
Elaina Claus	69223a1ad2	explaination on the power of two stuff All checks were successful Daily Build and trunk tester / debian_update (push) Successful in 1m21s Details	2025-09-05 20:54:29 -04:00
Elaina Claus	130cd22ff1	remove unreal mode stuff from cdecl16.inc	2025-09-05 20:33:00 -04:00
Elaina Claus	4e5112b45b	move unreal mode hackery back to stage2.nasm	2025-09-05 20:32:19 -04:00
Elaina Claus	66e8e3c7fc	prototype allocate function	2025-09-05 19:55:08 -04:00
Elaina Claus	b0bd4b27b0	🎉 simple allocator init in the code	2025-09-05 16:48:24 -04:00
Elaina Claus	cd316afdd1	basic arena allocator implementation	2025-09-05 16:42:25 -04:00
Elaina Claus	9a478aa4d4	added another __REFLAT variant	2025-09-05 16:28:01 -04:00
Elaina Claus	31d05c35e5	move __TINY_DS_ES to unreal_mode function also some cleanup	2025-09-05 16:18:34 -04:00
Elaina Claus	534e04ef34	fix a typo	2025-09-05 15:48:43 -04:00
Elaina Claus	f58bf93507	don't exit if we are running as root just warn	2025-09-05 15:45:33 -04:00
Elaina Claus	b5ae11f850	set ds/es to a tiny memory model after entering Unreal mode ss/fs/gs will all be huge/flat model after	2025-09-05 15:43:22 -04:00
Elaina Claus	b9b3e92632	actually set cs to 16-bit segment for a bit in-case we want to run some pm code	2025-09-05 15:26:24 -04:00
Elaina Claus	5fac10f02c	use easier to read logic	2025-09-05 14:40:44 -04:00
Elaina Claus	fa4524aa59	add macros to go from real <-> unreal	2025-09-05 14:39:16 -04:00
Elaina Claus	01ec6da0cc	make unreal mode unreal again	2025-09-05 11:45:46 -04:00
Elaina Claus	2e2b4f991d	add cursor manipulation via bios or crtc	2025-09-05 11:45:20 -04:00
Elaina Claus	d7b29d9113	__CDECL16_ENTRY now takes 0-1 params, if you give it a size it sets up local varible redzone	2025-09-05 11:44:30 -04:00
Elaina Claus	69d82dc0c2	small comment update	2025-09-05 11:43:41 -04:00
Elaina Claus	a53534acd2	clear the carry flag before calling BIOS functions	2025-09-05 10:33:42 -04:00
Elaina Claus	c3871d2b7d	move string functions to video.nasm caught a bug where SetTextMode was setting mono text not 16-color mode	2025-09-05 10:33:03 -04:00
Elaina Claus	d824493ba2	small clarification on what "unreal" mode really is	2025-09-05 09:12:55 -04:00
Elaina Claus	cb089681cf	make arena_align_up use 16-bit values	2025-09-05 09:12:26 -04:00
Elaina Claus	d868008726	another oopsie from when I changed the calling convention...	2025-09-05 08:43:41 -04:00
Nivirx	935427509a	inital code for align_up function	2025-09-05 08:27:56 -04:00
Elaina Claus	f5e4927d70	add basic arena area init code Some checks failed Daily Build and trunk tester / debian_update (push) Failing after 1m14s Details	2025-09-04 20:04:25 -04:00
Elaina Claus	b106eae066	fix alignment macros	2025-09-04 20:04:03 -04:00
Elaina Claus	f2657fdc01	seems I found a /little/ oopsie in the fat32 system	2025-09-04 19:59:36 -04:00
Elaina Claus	86d966811b	prototypes for displaying some memory maps but now I need to write an arena allocator...so brb	2025-09-04 17:51:52 -04:00
Elaina Claus	c10394a0cd	early allocator prototypes	2025-09-04 17:49:57 -04:00
Elaina Claus	28b23b9ce2	paragraph align the values in bss	2025-09-04 15:32:42 -04:00
Elaina Claus	105ceb8b8b	make sure eax and edx are set each call to E820	2025-09-04 15:32:28 -04:00
Elaina Claus	7fd5b9b85d	wx is still broken, also point to disk.img in build/	2025-09-04 15:31:39 -04:00
Elaina Claus	a618a837d4	added root check back in, but check that we aren't root changed how mtools accesses images, should functionally be the same.	2025-09-04 12:29:57 -04:00
Elaina Claus	930d49c353	Delete LICENSE.md GPLv3 is in COPYING, remove LICENSE.md	2025-09-04 10:11:36 -04:00
Elaina Claus	06d00d02e2	Update .github/workflows/daily.yaml oh boy, github actions as well	2025-09-04 09:19:23 -04:00
Elaina Claus	61379e8116	add a daily cron and general build action for github actions	2025-09-04 08:58:45 -04:00
Elaina Claus	828428e73b	removed debug files (they were moved earlier) All checks were successful Daily Build and trunk tester / debian_update (push) Successful in 1m19s Details	2025-08-24 10:47:54 -04:00
Elaina Claus	402bf9974d	moved map file output to build moved output of builds to build/output updated gitea action	2025-08-24 10:47:18 -04:00
Elaina Claus	5dfc3533d9	ignore everything in build output manually track .keep_dir files	2025-08-24 10:19:10 -04:00
Elaina Claus	d9225718c2	moving some documentation around and a bit of build cleanup	2025-08-24 10:18:01 -04:00
Elaina Claus	8a6730bc9c	Update README.md All checks were successful Daily Build and trunk tester / debian_update (push) Successful in 1m27s Details	2025-08-23 09:32:44 -04:00
Elaina Claus	67523208b3	Update scripts/create-disk.sh fix label-id, was a bit over the ballmer ridge	2025-08-23 08:35:26 -04:00
Elaina Claus	ffe887b6a9	Update .gitea/workflows/onpush.yaml All checks were successful Daily Build and trunk tester / debian_update (push) Successful in 1m34s Details	2025-08-22 22:45:59 -04:00
Elaina Claus	c45e62ecc2	Merge branch 'trunk' of chtm-lapp-02.lan.chtm.me:nivirx/stevia into trunk	2025-08-22 22:43:40 -04:00
Elaina Claus	d7c50575cf	re-wrote crate-disk.sh to not need root access, now requires mtools removed macOS support in disk creation script	2025-08-22 22:43:24 -04:00