more rtfm'ing with encoding, 25 bytes of free code space in vbr now

mbr now has 93 bytes free for more code

.gitea/workflows/onpush.yaml

@@ -0,0 +1,40 @@
+name: Daily Build and trunk tester
+on:
+  push:
+    branches: [ $default-branch ]
+  pull_request:
+    branches: [ $default-branch ]
+  schedule:
+    - cron: "0 7 * * *"   # daily 07:00
+  workflow_dispatch: {}
+
+jobs:
+  debian_update:
+    runs-on: debian-trixie
+    steps:
+      - name: Checkout (if needed)
+        uses: actions/checkout@v4
+
+      - name: Install CHTM apt cache endpoint into container
+        run: |
+          echo 'Acquire::http::Proxy "http://chtm-aptcache-01.lan.chtm.me:3142";' | tee /etc/apt/apt.conf.d/01aptproxy
+      
+      - name: Ensure image is up to date and install build tools and deps
+        run: |
+          bash -c "apt update && apt upgrade -y"
+          apt install -y build-essential nasm mtools fdisk dosfstools 
+
+      - name: Build stevia
+        run: make
+
+      - name: Upload build artifacts
+        if: always()   # still keep logs/artifacts even if build fails
+        uses: actions/upload-artifact@v3
+        with:
+          name: stevia-${{ 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: 30   # override server default if you like

.github/workflows/daily.yaml

@@ -0,0 +1,35 @@
+name: Daily Build and trunk tester
+on:
+  push:
+    branches: [ $default-branch ]
+  schedule:
+    - cron: "0 7 * * *"   # daily 07:00
+  workflow_dispatch: {}
+
+jobs:
+  debian_update:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout (if needed)
+        uses: actions/checkout@v4
+      
+      - name: Update and install build tools and deps
+        run: |
+          sudo bash -c "apt update && apt upgrade -y"
+          sudo apt install -y build-essential nasm mtools fdisk dosfstools 
+
+      - name: Build stevia
+        run: make
+
+      - name: Upload build artifacts
+        if: always()   # still keep logs/artifacts even if build fails
+        uses: actions/upload-artifact@v4
+        with:
+          name: stevia-${{ 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
+          

.gitignore

@@ -1,10 +1,13 @@
-out/*
 build/*
+build/output/*
 *.img
 *.img.gz
+*.img.gz
 *.elf
 bx_enh_dbg.ini
 stevia-log
 .vscode/
 *.map
 compose-dev.yaml
+eth_null-tx.log
+eth_null-txdump.txt

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/>.

Makefile

@@ -13,74 +13,111 @@
 #     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 \
+    -device usb-ohci,id=ohci0 \
+    -device usb-ehci,id=ehci0 \
+    -device pcspk \
+    -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)
+.DEFAULT_GOAL := all
+.DELETE_ON_ERROR:
+
+.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: $(BOOTTEST_BINS)
+
+# Build Rules
+
+$(BUILD_DIR)/mbr/%.bin: src/mbr/%.nasm | $(DEP_DIR)
+	@mkdir -p $(@D)
+	@nasm $(NASMFLAGS) -MD $(DEP_DIR)/$*.d -MT $@ $< -o $@
+
+$(BUILD_DIR)/vbr/%.bin: src/vbr/%.nasm | $(DEP_DIR)
+	@mkdir -p $(@D)
+	@nasm $(NASMFLAGS) -MD $(DEP_DIR)/$*.d -MT $@ $< -o $@
+
+$(BUILD_DIR)/stage2/%.bin: src/stage2/%.nasm | $(DEP_DIR)
+	@mkdir -p $(@D)
+	@nasm $(NASMFLAGS) -MD $(DEP_DIR)/$*.d -MT $@ $< -o $@
+
+$(BUILD_DIR)/miniboot32/%.bin: src/miniboot32/%.nasm | $(DEP_DIR)
+	@mkdir -p $(@D)
+	@nasm $(NASMFLAGS) -MD $(DEP_DIR)/$*.d -MT $@ $< -o $@
+
+
+$(DEP_DIR):
+	@mkdir -p $@
+
+# Disk image's
+
+$(IMG): $(ALL_BINS) | scripts/create-disk.sh
+	@scripts/create-disk.sh
+
+$(IMGZ): $(IMG)
+	@gzip -9kc $(IMG) > $(IMGZ)
+
+img: $(IMG)
+	@file $(IMG)
+
+imgz: $(IMGZ)
+	@file $(IMGZ)
+
+# Helpers
+
+run: $(IMG)
+	@$(QEMU) $(QEMU_OPTS) -drive file=$(IMG),if=ide,index=0,media=disk,format=raw \
+
+run_bochs: $(IMG)
 	@bochs -q
 
-iso: $(iso)
-	@file $(iso)
+clean:
+	@$(RM) -rv $(BUILD_DIR)/
 
-isoz: $(isoz)
-	@file $(isoz)
+help:
+	@awk '/^[A-Za-z0-9_%-]+:/{print $$1}' $(MAKEFILE_LIST) | sed 's/:$$//' | sort -u
 
-build/%.bin: src/mbr/%.nasm
-	@mkdir -p $(shell dirname $@)
-	@nasm -i$(include) -Wall -f bin $(GIT_NASM_DEFINES) $< -o $@
-
-build/%.bin: src/vbr/%.nasm
-	@mkdir -p $(shell dirname $@)
-	@nasm -i$(include) -Wall -f bin $(GIT_NASM_DEFINES) $< -o $@
-
-build/%.bin: src/stage2/%.nasm
-	@mkdir -p $(shell dirname $@)
-	@nasm -i$(include) -Wall -f bin $(GIT_NASM_DEFINES) $< -o $@
-
-build/%.bin: src/miniboot32/%.nasm
-	@mkdir -p $(shell dirname $@)
-	@nasm -i$(include) -Wall -f bin $(GIT_NASM_DEFINES) $< -o $@
-
-$(iso): $(mbr_binary_files) $(vbr_binary_files) $(stage2_binary_files) $(boottest_binary_files)
-	@echo root access needed to create disk image...
-	@sudo scripts/create-disk.sh
-
-$(isoz): $(iso)
-	@gzip -9kc $(iso) > $(isoz)
+# Include header deps
+-include $(wildcard $(DEP_DIR)/*.d)

README.md

@@ -1,6 +1,6 @@
 # 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 and C, designed for educational purposes. It targets 686+ and aims to be simple, approachable, and understandable, focusing on minimalism and core functionality.
 
 ## Features
 
@@ -10,18 +10,13 @@ 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 +24,38 @@ 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.
-
-## 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.
+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.
 
 ## 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.

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

include/BIOS/func/E820_memory_map.nasm

@@ -35,28 +35,33 @@ endstruc
 
 ALIGN 4, db 0x90
 GetMemoryMap:
-    __CDECL16_ENTRY
+    __CDECL16_PROC_ENTRY
     push es         ; save segment register
 .func:
     mov dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries], 0
 
-    mov eax, 0xE820                         ; select 0xE820 function
+    
     xor ebx, ebx                            ; Continuation value, 0 for the first call
 
-    lea dx, [BIOSMemoryMap]
+    mov 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 ecx, AddressRangeDescStruct_t_size  ; hard request ACPI 3.0 table versions (24 bytes)
+    
 .loop_L1:
+    mov eax, 0x0000E820                     ; select 0xE820 function
+    mov edx, 0x534D4150                     ; 'SMAP' magic
+    clc                                     ; clear carry
     int 0x15
     jc GetMemoryMap.error
     cmp eax, 0x534D4150
     jne GetMemoryMap.no_smap_returned
 .no_error:
-    inc dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries]
+    mov eax, dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries]
+    add eax, 1
+    mov dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries], eax
 
     cmp ecx, 20                             ; TODO: maybe this could be handled better than just panicing
     jb GetMemoryMap.nonstandard_e820        ; non-standard entry found 
@@ -64,9 +69,11 @@ 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 +83,40 @@ 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.MemoryMapEntries]
+    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

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

include/BIOS/func/ext_read.nasm

@@ -76,7 +76,7 @@ endstruc
 ;                         uint16_t count, uint8_t drive_num)
 ALIGN 4, db 0x90
 read_disk_raw:
-    __CDECL16_ENTRY
+    __CDECL16_PROC_ENTRY
 .func:                        
     mov ax, LBAPkt_t_size
     push ax                 ; len
@@ -111,6 +111,7 @@ read_disk_raw:
     mov ah, 0x42                ; call #
     mov dl, byte [bp + 14]      ; drive #             
 
+    clc                         ; clear carry
     int 0x13
     jnc .endf
 
@@ -122,7 +123,7 @@ read_disk_raw:
     ERROR STAGE2_MBR_DISK_READ_ERROR
     %endif
 .endf:
-    __CDECL16_EXIT
+    __CDECL16_PROC_EXIT
     ret
 
 %endif

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

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
@@ -36,19 +39,88 @@
 %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
+%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!
+%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
 

include/fat32/FAT32_SYS.nasm

@@ -0,0 +1,160 @@
+; 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/bpb_offset_bx.inc"
+%include "fat32/fat32_structures.inc"
+
+; 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);
+
+; 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(uint32_t partition_lba, fat32_bpb_t* out);
+
+
+;
+; Accessors
+;
+
+; // Convert cluster -> LBA of first sector of that cluster
+; uint64_t clus_to_lba(const fat32_bpb_t* v, uint32_t clus) {
+;  return v->data_lba + (uint64_t)(clus - 2) * v->secs_per_clus;
+; }
+
+; FAT32 entry is 32-bits; only low 28 bits are meaningful.
+;   EOC if (val & 0x0FFFFFFF) >= 0x0FFFFFF8.
+;   bad if == 0x0FFFFFF7.
+;   free if == 0x00000000.
+
+; // Read 32-bit FAT entry for cluster n
+; int fat32_read_fat(const fat32_bpb_t* v, uint32_t clus, uint32_t* out);
+
+; // Walk to next cluster in chain (validates EOC/bad)
+; int fat32_next_clus(const fat32_bpb_t* v, uint32_t clus, uint32_t* out_next);
+
+;
+; 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

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

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

include/util/arena_alloc.nasm

@@ -0,0 +1,169 @@
+%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)
+;
+arena_init:
+    __CDECL16_PROC_ENTRY
+.func:
+    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
+    mov ax, __ARENA_HEAP_SIZE
+    push ax                     ; len
+    xor ax, ax
+    push ax                     ; val = 0
+    mov ax, __ARENA_HEAP_START
+    push ax                     ; 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
+arena_align_up:
+    __CDECL16_PROC_ENTRY
+.func:
+    ; if a == 0 return x
+    mov ax, [bp + 4]      ; x
+    mov bx, [bp + 6]      ; a
+
+    test bx, bx
+    jz .endp              
+
+    ; 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 .endp
+
+    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
+.endp:
+    __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
+arena_alloc:
+    __CDECL16_PROC_ENTRY 0x10
+.func:
+    ; 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
+
+    mov ax, word [bp + 6]           ; requested next allocation alignment
+    push ax
+    mov ax, word [bp - 2]           ; current arena 'highmark'
+    push ax
+    call arena_align_up
+    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 arena_alloc.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
+.func:
+    ; 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
+.func:
+    ; rewind the arena to a previously marked point
+    ERROR STEVIA_DEBUG_UNIMPLEMENTED
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+
+arena_reset:
+    __CDECL16_PROC_ENTRY
+.func:
+    ; reset the entire heap to a fresh state
+    ERROR STEVIA_DEBUG_UNIMPLEMENTED
+.endp:
+    __CDECL16_PROC_EXIT
+    ret
+
+%endif
+%define __INC_ARENA_ALLOC_FUNC

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

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

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

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 [[ "$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
-
-        # create a DOS disk, with 1 FAT32 partition that is bootable, part1 starts at sector 2048
-        sfdisk $ld < scripts/loop_setup.sfdisk
-
-        # get first partition, this is sloppy might need to review this...
-        firstpart=$(lsblk -ilp -o NAME $ld | tr '\n' ' ' | awk '{print $3}')
-        mkfs.fat -v -F32 -s 1 -n 'STEVIAFS' $firstpart
-
-        #
-        # MBR setup
-        #
-
-        # copy MBR while preserving partition table
-        if ! dd if=$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=$firstpart bs=1 count=3; then
-            echo "Failed to write VBR to disk. (part 1)" >&2
-            exit 1
-        fi
-        # copy bootcode
-        if ! dd if=$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 $disk_tmp_file
-
-    else
-        echo "unable to find MBR/VBR binaries!" >&2
+if ! [ -e "$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
-# 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 > $disk_file_final
-    else
-        echo "unable to find MBR/VBR binaries!"
-        exit 2
+    sync
+else
+    echo "Removing old (partition) disk image..."
+    rm -rfv "$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 [[ "$OSTYPE" == "linux-gnu"* ]]; then
+        echo "[2/7] Write DOS partition table (single FAT32 LBA @ 2048)"
+        "$SF" --no-reread "$disk_img" < /tmp/pt.sfdisk
+
+        # BUG: the default disk img is 256MiB which mkfs.fat wants to create
+        #      a FAT16 FS by default. it needs to be at least 2GiB to to 'lock out'
+        #      FAT16 as an option. Force FAT32 here, might(?) break some things.
+        echo "[3/7] Make FAT filesystem in partition image"
+        "$MKFS" -F32 -v -n 'STEVIAFS' "$part_img"
+
+        echo "[4/7] Patch VBR inside partition image (preserve BPB)"
+
+        # copy jmp short entry; nop
+        dd if=$vbr_file of="$part_img" bs=1 count=3 conv=notrunc
+        # copy bootcode
+        dd if=$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

scripts/loop_setup.sfdisk

@@ -1,5 +0,0 @@
-label: dos
-unit: sectors
-sector-size: 512
-
-start=        2048, type=c, bootable

src/mbr/mbr.nasm

@@ -18,7 +18,7 @@
 [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
@@ -33,7 +33,6 @@ nop
 %include "config.inc"
 %include "error_codes.inc"
 %include "partition_table.inc"
-%include "fat32/fat32_structures.inc"
 
 %undef __STEVIA_DEV_DEBUG
 
@@ -58,7 +57,7 @@ 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
@@ -96,6 +95,8 @@ 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
@@ -119,19 +120,14 @@ 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 VBR_ENTRY                                ; offset = 0x7c00 (2)
+        push 0x00                                          ; segment = 0 (2)
 
         ; uint8_t read_stage2_raw(uint16_t buf_segment, uint16_t buf_offset, 
         ;                         uint32_t lba,
@@ -141,14 +137,11 @@ main:
     .goto_vbr:
         cmp word [VBR_ENTRY + 0x1FE], 0xAA55
         je main.sig_ok
-        ERROR MBR_ERROR_NO_VBR_SIG                        ; no signature present
+        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
+        push PartTable_t_size                   ; len       
+        push DiskSig                            ; src -> start of partition table
+        push partition_table                    ; dst -> addr in bss 
         call kmemcpy                            ; copy partition table to bss
         add sp, 0x6
         
@@ -194,7 +187,7 @@ 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 512 - 16                 ; 512 byte stack early on
 stack_top:
-mbr_redzone resb 32
+mbr_redzone resb 16
 end_bss:

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.
@@ -34,13 +34,6 @@
 %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
@@ -88,7 +81,7 @@ init:
     jmp word __STAGE2_SEGMENT:main
 
 ; ###############
-; Functions
+; Core Functions
 ; ###############
 
 %include "util/kmem_func.nasm"
@@ -96,11 +89,19 @@ 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/bpb_offset_bx.inc"
+%include "fat32/fat32_structures.inc"
+;%include 'fat32/FAT32_SYS.inc'
 
 ; ###############
 ; BIOS functions
@@ -130,55 +131,58 @@ 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
+    ; copy partition table data to .data section in stage2
+    __CDECL16_CALL_ARGS partition_table, word [vbr_part_table_ptr], PartTable_t_size
+    __CDECL16_CALL kmemcpy, 3
 
-    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
+    ; copy bpb & ebpb to memory
+    __CDECL16_CALL_ARGS fat32_bpb, word [vbr_fat32_bpb_ptr], (FAT32_bpb_t_size + FAT32_ebpb_t_size) 
+    __CDECL16_CALL kmemcpy, 3
 
     call SetTextMode
-    call disable_cursor
-    print_string HelloPrompt_info
+    call disable_cursor_bios
+
+    __CDECL16_CALL_ARGS HelloPrompt_info
+    __CDECL16_CALL PrintString, 1
+
+    ; setup the early heap
+    __CDECL16_CALL_ARGS early_heap_state
     
     ; enable A20 gate
     call EnableA20
-    print_string A20_Enabled_OK_info
+    __CDECL16_CALL_ARGS A20_Enabled_OK_info
+    __CDECL16_CALL PrintString, 1
 
     ; get system memory map
     call GetMemoryMap
-    print_string MemoryMap_OK_info
+    __CDECL16_CALL_ARGS MemoryMap_OK_info
+    __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 UnrealMode_OK_info
+    __CDECL16_CALL PrintString, 1
 
     ; FAT Driver setup
-    call InitFATDriver
-    print_string InitFATSYS_OK_info
+    ;call InitFATDriver
+    ;__CDECL16_CALL_ARGS InitFATSYS_OK_info
+    ;__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 FileFound_OK_info
+    ;__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
@@ -187,166 +191,103 @@ 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
-
-    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:
-    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    
+; 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
 
+; for copying between locations in high memory
+%ifnmacro __REFLAT_DS_ES
+%macro __REFLAT_DS_ES 0
+    cli                                   ; no interrupts   
     lgdt [((__STAGE2_SEGMENT << 4) + unreal_gdt_info)]                 ; 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) + unreal_gdt_info)]                 ; 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
+.func:    
+    lgdt [((__STAGE2_SEGMENT << 4) + unreal_gdt_info)]                 ; 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:
 
@@ -361,13 +302,13 @@ begin_data:
 %define CRLF 0Dh, 0Ah
 
 %macro define_cstr 2
-    ALIGN 16
+    align 16
     %1_cstr:
         db %2, 00h
 %endmacro
 
 %macro define_info 2
-    ALIGN 16
+    align 16
     %1_info:
         db %2, CRLF, 00h
 %endmacro
@@ -386,7 +327,7 @@ define_info MaybeFound_Boot, "Maybe found a file...checking..."
 
 define_cstr BootTarget, "BOOT    BIN"
 
-ALIGN 16, db 0
+align 16, db 0
 BootTarget:
     db 'BOOT    BIN'
 
@@ -394,28 +335,28 @@ BootTarget:
 ; pre-bss init globals (generally const...but there are exceptions)
 ;
 
-align 8, db 0x00
+align 8, db 0
 boot_drive:
     db 0x00
 
-align 8, db 0x00
+align 8, db 0
 partition_offset:
     dw 0x0000
 
-align 8, db 0x00
+align 8, db 0
 vbr_fat32_bpb_ptr:
     dw 0x0000
 
-align 8, db 0x00
+align 8, db 0
 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
+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)
@@ -423,14 +364,14 @@ unreal_gdt_start:
     ; 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
@@ -438,7 +379,7 @@ unreal_gdt_start:
     db 0x00              ; Base Address(31:24)
 unreal_gdt_end:
 
-ALIGN 16, db 0
+align 16, db 0
 gdt32_info:
     gdt32_size: dw (gdt32_end - gdt32_start) - 1
     gdt32_ptr:  dd ((__STAGE2_SEGMENT << 4) + gdt32_start)
@@ -474,19 +415,19 @@ gdt32_start:
         db 0x00
 gdt32_end:
 
-ALIGN 8,db 0x00
+align 16,db 0
 BUILD_NASM_VER:
     db "Stevia Stage2 built with NASM - ", __NASM_VER__, 00h
 
-ALIGN 8,db 0x00
+align 16,db 0
 BUILD_DATETIME:
     db 'Assembled - ', __DATE__, ' ', __TIME__, 00h
 
-ALIGN 8,db 0x00
+align 16,db 0
 BUILD_GIT_VER:
     db __GIT_VER__, 00h
 
-ALIGN 8,db 0x00
+align 16,db 0
 BUILD_GIT_HASH:
     db __GIT_HASH__, 00h
 end_data:
@@ -504,26 +445,35 @@ section .bss follows=.sign
 begin_bss:
 ; structures
 
-align 8, resb 1
-partition_table resb PartTable_t_size
+align 16, 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 16, 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 16, resb 1
+fat32_nc_data: 
+    resb 16
 
-align 8, resb 1
-lba_packet resb LBAPkt_t_size
+align 16, resb 1
+lba_packet: 
+    resb LBAPkt_t_size
 
-align 8, resb 1
+align 16, resb 1
 fat32_state:
     resb FAT32_State_t_size
 
-align 8, resb 1
+align 16, resb 1
 SteviaInfo:
     resd 4
+
+align 16, resb 1
+early_heap_state:
+    resb ArenaStateStruc_t_size
 ;
 ; post-bss init globals
 ;
@@ -541,12 +491,15 @@ dir_buffer:
 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
+    resb BIOSMemoryMap_SIZE
 
-align 512, resb 1
+align 16, resb 1
 stack_bottom:
     resb 1024
 stack_top:

src/vbr/vbr.nasm

@@ -17,7 +17,7 @@
 [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:
@@ -72,7 +72,7 @@ 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
@@ -101,22 +101,16 @@ main:
     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
+    push PartTable_t_size                              ; count=                                    
+    push word [bp - 6]                                 ; src= ptr partition_table                                
+    push partition_table                               ; dst=
+    call kmemcpy                                       ; copy partition table data to bss
     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
+    push (FAT32_bpb_t_size + FAT32_ebpb_t_size)        ; size in byte, should be 90 bytes                                     
+    push __ENTRY                                       ; src
+    push fat32_bpb                                     ; dst
+    call kmemcpy                                       ; copy bpb & ebpb to bss
     add sp, 0x6
 
 .check_FAT_size:                     ; we only support a very specific setup of FAT32
@@ -129,17 +123,13 @@ 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,
@@ -166,6 +156,7 @@ 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:
@@ -177,14 +168,11 @@ 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 (512 - 16)                  ; 512b stack early on
 stack_top:
-vbr_redzone resb 32
+vbr_redzone resb 16
 end_bss: