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stick mmap info in SteviaInfo

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This commit is contained in:
Elaina Claus
2025-09-17 16:24:27 -04:00
parent 8b0b73d8a4
commit 59bc1afb7c
2 changed files with 25 additions and 87 deletions
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20
include/BIOS/func/E820_memory_map.nasm
View File

@@ -33,35 +33,27 @@ struc AddressRangeDescStruct_t
.ExtType resd 1
endstruc
; !!! this procedure changes ES !!!
ALIGN 4, db 0x90
GetMemoryMap:
__CDECL16_PROC_ENTRY
push es ; save segment register
.func:
mov dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries], 0
mov word [SteviaInfo + SteviaInfoStruct_t.u16_E820MMapEntryCount], 0
xor ebx, ebx ; Continuation value, 0 for the first call
mov dx, BIOSMemoryMap
shr dx, 4
mov es, dx
xor di, di ; (BIOSMemoryMap >> 4):0 makes di an index into BIOSMemoryMap
mov di, BIOSMemoryMap ; destination is es:di, es should == ds
mov ecx, AddressRangeDescStruct_t_size ; hard request ACPI 3.0 table versions (24 bytes)
.loop_L1:
mov eax, 0x0000E820 ; select 0xE820 function
mov edx, 0x534D4150 ; 'SMAP' magic
clc ; clear carry
int 0x15
int 0x15 ; data will be stored at es:di by e820 call
jc GetMemoryMap.error
cmp eax, 0x534D4150
jne GetMemoryMap.no_smap_returned
.no_error:
mov eax, dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries]
add eax, 1
mov dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries], eax
inc word [SteviaInfo + SteviaInfoStruct_t.u16_E820MMapEntryCount]
cmp ecx, 20 ; TODO: maybe this could be handled better than just panicing
jb GetMemoryMap.nonstandard_e820 ; non-standard entry found
@@ -89,7 +81,7 @@ GetMemoryMap:
PrintMemoryMap:
__CDECL16_PROC_ENTRY
.func:
mov eax, dword [SteviaInfo + SteviaInfoStruct_t.MemoryMapEntries]
mov eax, dword [SteviaInfo + SteviaInfoStruct_t.u16_E820MMapEntryCount]
cmp eax, 0
je PrintMemoryMap.endp ; if entries == 0, exit

92
src/stage2/stage2.nasm
View File

@@ -102,8 +102,10 @@ init:
; structures
struc SteviaInfoStruct_t
.MemoryMapPtr resd 1
.MemoryMapEntries resd 1
.p16_E820MemoryMapPtr resw 1
.u16_E820MMapEntryCount resw 1
.p16_MbrPtr resw 1
.p16_VbrPtr resw 1
endstruc
struc EarlyBootStruct_t
@@ -130,20 +132,20 @@ main:
__CDECL16_CALL_ARGS pszHelloPrompt
__CDECL16_CALL PrintString, 1
; setup and store our vbr/mbr (e)bpb
__CDECL16_CALL_ARGS 0x200, 0x10
__CDECL16_CALL ArenaAlloc, 2
mov word [mbr_ptr], ax
mov word [SteviaInfo + SteviaInfoStruct_t.p16_MbrPtr], ax
push ax ; dst
movzx ax, byte [u8_BootDrive]
push ax ; boot_drive
__CDECL16_CALL ReadMbrData, 2 ; fill mbr buffer
__CDECL16_CALL ReadMbrData, 2 ; fill mbr buffer
__CDECL16_CALL_ARGS 0x200, 0x10
__CDECL16_CALL ArenaAlloc, 2
mov word [vbr_ptr], ax
mov word [SteviaInfo + SteviaInfoStruct_t.p16_VbrPtr], ax
push ax ; dst
movzx ax, byte [u8_BootDrive]
@@ -218,10 +220,6 @@ ReadMbrData:
cmp word [bx + 0x1FE], 0xAA55 ; check for bytes at end
jne ReadMbrData.error
; TODO: this needs error checking, zero checking, check the sig a bunch of stuff...
.update_globals:
mov ax, [bp + 6]
add ax, 0x1B8 ; offset to start of PartTable
mov [part_table_ptr], ax
.endp:
__CDECL16_PROC_EXIT
ret
@@ -233,19 +231,21 @@ ReadMbrData:
ReadVbrData:
__CDECL16_PROC_ENTRY
.proc:
mov bx, word [part_table_ptr] ; calculate offset; base pointer @ partition table
mov bx, SteviaInfo
mov ax, word [bx + SteviaInfoStruct_t.p16_MbrPtr]
add ax, DISK_PARTITION_TABLE_OFFSET
mov bx, ax ; offset to part table
mov cx, 4 ; only checking 4 entries
mov si, PartEntry_t.attributes
.find_active_L0:
mov al, byte [bx + si]
test al, 0x80 ; 0x80 == 1000_0000b
je ReadVbrData.active_found
add si, 0x10 ; add 16 bytes to offset (next part entry's attributes)
add bx, PartEntry_t_size ; next part entry's attributes
loop ReadVbrData.find_active_L0
jmp ReadVbrData.error
.active_found:
add bx, si ; update base to active part
movzx ax, byte [bp + 4]
push ax ; drive_num (2)
push 0x01 ; count (2)
@@ -265,10 +265,6 @@ ReadVbrData:
.check_FAT_size:
test word [bx + FAT32_bpb_t.unused2_ZERO_word], 0 ; TotSectors16 will not be set if FAT32
jnz ReadVbrData.error
.update_globals:
mov word [fat32_bpb_ptr], bx
add bx, FAT32_bpb_t_size ; offset to ebpb
mov word [fat32_ebpb_ptr], bx
.endp:
__CDECL16_PROC_EXIT
ret
@@ -510,72 +506,22 @@ align 16, resb 1
section .bss follows=.sign
begin_bss:
align 4, resb 1
mbr_ptr:
resw 1
align 4, resb 1
vbr_ptr:
resw 1
align 4, resb 1
part_table_ptr:
resw 1
align 4, resb 1
fat32_bpb_ptr:
resw 1
align 4, resb 1
fat32_ebpb_ptr:
resw 1
; structures
align 16, resb 1
partition_table:
resb PartTable_t_size
SteviaInfo:
resd SteviaInfoStruct_t_size
align 16, resb 1
fat32_bpb:
resb FAT32_bpb_t_size
fat32_ebpb:
resb FAT32_ebpb_t_size
align 16, resb 1
fat32_nc_data:
resb 16
early_heap_state:
resb ArenaStateStruc_t_size
align 16, resb 1
lba_packet:
resb LBAPkt_t_size
align 16, resb 1
fat32_state:
resb FAT32_State_t_size
align 16, resb 1
SteviaInfo:
resd 4
align 16, resb 1
early_heap_state:
resb ArenaStateStruc_t_size
;
; post-bss init globals
;
;
; large continuous allocations
;
align 16, resb 1
disk_buffer:
resb 512
fat_buffer:
resb 512
dir_buffer:
resb 512
fat_fsinfo:
resb 512
; TODO: this will hold 42 entries from the map function
; the e820 function needs to check that it doesn't overflow
@@ -593,7 +539,7 @@ end_bss:
; Pad to the cap (emits nothing in the file; only increases .bss virtual size).
; If BSS_SIZE > BSS_MAX_BYTES, this becomes negative and NASM errors out.
%define BSS_MAX_BYTES 0x3000
%define BSS_MAX_BYTES 0x2000
resb (BSS_MAX_BYTES - (end_bss - begin_bss))
; Optional: keep a label for later math: