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Implement lba read

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This commit is contained in:
Nero 2020-05-08 20:48:23 +00:00
parent a472c396e7
commit 2cb39a4ff1
1 changed files with 40 additions and 16 deletions
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56
kernel/diskio.asm
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@ -9,27 +9,28 @@ disk_current:
lba_supported: lba_supported:
resb 1 resb 1
; Seek state and geometry info for CHS access
disk_chs: ; DL, DH, CL, CH for int 13h CHS functions disk_chs: ; DL, DH, CL, CH for int 13h CHS functions
resb 4 resb 4
disk_dap: ; disk access packet for int 13h EBIOS functions
resb 0x10
disk_spc: ; sectors per cylinder = heads * spt disk_spc: ; sectors per cylinder = heads * spt
resw 1 resw 1
disk_spt: disk_spt:
resb 1 resb 1
; Partition conf from MBR or dummy for floppies
part_offset: part_offset:
resd 1 resd 1
part_size: part_size:
resd 1 resd 1
; Disk access packet for EBIOS extensions dap: ; Disk access packet for EBIOS extensions
dapps: equ 0 ; byte packet size resw 1
dapnum: equ 2 ; word number of sectors to transfer dap_sectors:
dapbuf: equ 4 ; dword transfer buffer resw 1
dapsec: equ 8 ; qword absolute sector number dap_buffer:
dapsiz: equ 16 resd 1
dap_sector:
resq 1
section .text section .text
@ -46,14 +47,15 @@ dncl: rcl dl, 1
ret ret
; Select a drive for I/O ; Select a drive for I/O
; This leave the first sector of the partition in the buffer
; IN dl 0=A, 1=B, 2=C, 3=D ; IN dl 0=A, 1=B, 2=C, 3=D
select: mov byte [disk_current], 0xFF select: mov byte [disk_current], 0xFF
mov byte [lba_supported], 0 mov byte [lba_supported], 0
cmp dl, 0x02
jc select_floppy
; detect EBIOS/LBA extensions
call dnconv call dnconv
mov byte [disk_chs], dl mov byte [disk_chs], dl
cmp dl, 0x80
jc select_floppy
; detect EBIOS/LBA extensions
mov ah, 0x41 mov ah, 0x41
mov bx, 0x55AA mov bx, 0x55AA
int 0x13 int 0x13
@ -123,6 +125,9 @@ seek: push ax
pop ax pop ax
jz seek_zero jz seek_zero
test byte [lba_supported], 1
jnz seek_lba
; dx:ax = lba ; dx:ax = lba
div word [disk_spc] div word [disk_spc]
xchg ax, dx xchg ax, dx
@ -147,14 +152,26 @@ seek_zero:
mov byte [disk_chs+1], 0 mov byte [disk_chs+1], 0
mov word [disk_chs+2], 1 mov word [disk_chs+2], 1
; set lba data to first sector ; set lba data to first sector
lea di, [disk_dap+dapsec]
mov cx, 4
xor ax, ax xor ax, ax
rep stosw xor dx, dx
seek_lba:
mov word [dap], 0x10
mov word [dap_sectors], 1
mov word [dap_buffer], disk_buffer
mov [dap_buffer+2], cs
lea di, [dap_sector]
stosw
mov ax, dx
stosw
xor ax, ax
stosw
stosw
ret ret
; Read a sector into buffer ; Read a sector into buffer
read: mov ax, 0x0201 read: test byte [lba_supported], 1
jnz read_lba
mov ax, 0x0201
mov dx, [disk_chs] mov dx, [disk_chs]
mov cx, [disk_chs+2] mov cx, [disk_chs+2]
lea bx, [disk_buffer] lea bx, [disk_buffer]
@ -163,6 +180,13 @@ read: mov ax, 0x0201
int 0x13 int 0x13
ret ret
read_lba:
mov ah, 0x42
mov dl, [disk_chs]
lea si, [dap]
int 0x13
ret
; Write a sector into buffer ; Write a sector into buffer
write: stc write: stc
ret ret