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might have fixed some of the boot_drive issues with ext_read

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This commit is contained in:
Elaina Claus
2024-12-19 13:13:46 -05:00
parent e33f010f73
commit 63a1a1beea
4 changed files with 57 additions and 55 deletions
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68
src/stage2/stage2.nasm
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@@ -49,14 +49,18 @@
section .text
begin_text:
; dl = byte boot_drive
; si = word part_offset (active partition offset)
; bx = ptr PartTable_t partition_table
; dx = ptr FAT32_bpb_t fat32_bpb
; ax = word part_offset (active partition offset)
; si = ptr PartTable_t partition_table
; di = ptr FAT32_bpb_t fat32_bpb
ALIGN 4, db 0x90
init:
__BOCHS_MAGIC_DEBUG
cli ; We do not want to be interrupted
mov [vbr_part_table_ptr], bx ; pointer to partition_table
mov [vbr_fat32_bpb_ptr], dx ; pointer to fat32_bpb
mov [boot_drive], dl ; copy boot_drive to globals
mov [partition_offset], ax ; copy partition_offset to globals
mov ax, __STAGE2_SEGMENT ; set all our segments to the configured segment, excep es
mov ds, ax ; *
mov fs, ax ; *
@@ -81,7 +85,7 @@ init:
mov sp, stack_top
mov bp, sp
sub sp, 0x20
sub sp, 0x10
push bp ; setup a somewhat normal stack frame, minus a ret ptr
sti
@@ -121,22 +125,9 @@ struc EarlyBootStruct_t
.fat32_ebpb resb FAT32_ebpb_t_size
endstruc
; bp - 2 : byte boot_drive
; bp - 4 : word part_offset
; bp - 6 : ptr PartTable_t partition_table
; bp - 8 : ptr FAT32_bpb_t fat32_bpb
ALIGN 4, db 0x90
main:
lea ax, [bp - 2]
mov [boot_drive_ptr], ax
lea ax, [bp - 4]
mov [partition_offset_ptr], ax ; setup pointers to boot_drive and partition offset on stack
mov byte [bp - 2], dl ; boot_drive (probably 0x80)
mov word [bp - 4], si ; partition_offset
mov word [bp - 6], bx ; partition_table
mov word [bp - 8], dx ; fat32_bpb
__BOCHS_MAGIC_DEBUG
.check_sig:
mov eax, dword [STAGE2_SIG]
cmp eax, 0xDEADBEEF
@@ -145,20 +136,20 @@ main:
.stage2_main:
mov ax, PartTable_t_size
push ax
mov ax, [bp - 6] ; ptr partition_table
mov ax, word [vbr_part_table_ptr] ; ptr partition_table
push ax
mov ax, partition_table
push ax
call kmemcpy ; copy partition table data
call kmemcpy ; copy partition table data
add sp, 0x6
mov ax, (FAT32_bpb_t_size + FAT32_ebpb_t_size) ; size in byte
push ax
mov ax, [bp - 8]
mov ax, word [vbr_fat32_bpb_ptr]
push ax
mov ax, fat32_bpb ; defined in memory.inc, destination
mov ax, fat32_bpb ; defined in memory.inc, destination
push ax
call kmemcpy ; copy bpb & ebpb to memory
call kmemcpy ; copy bpb & ebpb to memory
add sp, 0x6
call SetTextMode
@@ -503,33 +494,44 @@ section .bss follows=.sign
begin_bss:
; structures
align 16, resb 1
align 8, resb 1
partition_table resb PartTable_t_size
align 16, resb 1
align 8, resb 1
fat32_bpb resb FAT32_bpb_t_size
fat32_ebpb resb FAT32_ebpb_t_size
align 16, resb 1
align 8, resb 1
fat32_nc_data resb 16
align 16, resb 1
align 8, resb 1
lba_packet resb LBAPkt_t_size
align 16, resb 1
align 8, resb 1
fat32_state:
resb FAT32_State_t_size
align 16, resb 1
align 8, resb 1
SteviaInfo:
resd 4
;
; locals
; globals
;
boot_drive_ptr:
align 8, resb 1
boot_drive:
resb 1
align 8, resb 1
partition_offset:
resw 1
partition_offset_ptr:
align 8, resb 1
vbr_fat32_bpb_ptr:
resw 1
align 8, resb 1
vbr_part_table_ptr:
resw 1
;