From ad2d37c63ba70c403ab1265725631685ab6587dc Mon Sep 17 00:00:00 2001
From: Elaina Claus <elaina.claus@chtm.me>
Date: Sun, 13 Oct 2024 20:53:13 -0400
Subject: [PATCH] use bochs magic breakpoints in the error printer makes it
 easier to get a good state to do some investigating before reseting.

---
 include/util/bochs_magic.inc |  3 ++-
 include/util/error_func.nasm |  5 +++++
 src/stage2/stage2.nasm       | 42 ++++++++++++++++++++----------------
 3 files changed, 30 insertions(+), 20 deletions(-)

diff --git a/include/util/bochs_magic.inc b/include/util/bochs_magic.inc
index fa236fc..bc59c80 100644
--- a/include/util/bochs_magic.inc
+++ b/include/util/bochs_magic.inc
@@ -20,7 +20,8 @@
 
 %ifndef __INC_BOCHS_DEBUG_MAGIC
 
-;
+; for things like the error printer, opperate differently when we are targeting a dev (bochs) build
+%define __STEVIA_DEV_DEBUG
 ; port_e9_hack: enabled=1 needs to be set in bochsrc.txt/bxrc
 ;
 %ifnmacro __BOCHS_PRINTC
diff --git a/include/util/error_func.nasm b/include/util/error_func.nasm
index 5682266..271cf97 100644
--- a/include/util/error_func.nasm
+++ b/include/util/error_func.nasm
@@ -22,7 +22,12 @@
 
 %macro ERROR 1
     mov al, %1           ; al = 1 byte error code mapped to ascii values
+    %ifdef __STEVIA_DEV_DEBUG
+    __BOCHS_MAGIC_DEBUG
+    %endif
     jmp error
+    
+    
 %endmacro
 
 ; pass error as ascii character in al, errors a-zA-Z or 0-9
diff --git a/src/stage2/stage2.nasm b/src/stage2/stage2.nasm
index fb4e88a..994530d 100755
--- a/src/stage2/stage2.nasm
+++ b/src/stage2/stage2.nasm
@@ -86,11 +86,13 @@ init:
     mov ss, ax                        ; Set Stack Segment to data segment
     mov sp, stack_top                 ; Set Stack Pointer
 
+    mov ax, init
+    push ax                           ; simulate a return value to the begining of the stage2 loader
+
+    push bp
     mov bp, sp
     sub sp, 0x20                      ; 32 bytes for local varibles
-
     sti
-
     jmp word __STAGE2_SEGMENT:main
 
 ; ###############
@@ -106,11 +108,6 @@ init:
 ; FAT32 Driver
 ; ###############
 
-boot_drive_ptr:
-    dw 0x0000
-partition_offset_ptr:
-    dw 0x0000
-
 %include 'fat32/FAT32_SYS.inc'
 
 ; ###############
@@ -191,7 +188,6 @@ main:
     call InitFATDriver
     print_string InitFATSYS_OK_cstr
 
-    ERROR STEVIA_DEBUG_HALT
     ;
     ; Find first cluster of bootable file
     ;
@@ -201,11 +197,9 @@ main:
     push dword eax
     call PrintDWORD     ; void PrintDWORD(uint32_t dword)
     add sp, 0x4
-    print_string NewLine_cstr
-    
+    print_string NewLine_cstr  
 hcf:
-    hlt
-    jmp short (hcf - $$)
+    ERROR STEVIA_DEBUG_OK
 
 ; ##############################
 ;
@@ -505,6 +499,10 @@ stack_top:
 stage2_main_redzone:
     resb 32
 
+;
+; structures
+;
+
 align 16, resb 1
 partition_table resb PartTable_t_size
 
@@ -518,19 +516,25 @@ fat32_nc_data resb 16
 align 16, resb 1
 lba_packet resb LBAPkt_t_size
 
-align 16, resb 1
-SteviaInfo:
-    resd 4
 align 16, resb 1
 fat32_state:
     resb FAT32_State_t_size
 
 align 16, resb 1
-mbr_sector_data:
-    resb 512
-vbr_sector_data:
-    resb 512
+SteviaInfo:
+    resd 4
 
+;
+; locals
+;
+boot_drive_ptr:
+    resw 1
+partition_offset_ptr:
+    resw 1
+
+;
+; large continuous allocations
+;
 align 16, resb 1
 disk_buffer:
     resb 512