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cli
cld
mov edi, 0x211000
mov ecx, 256
rep insw ; or movs whatever..

Code: Select all

ata_rd:
; eax = lba
; edi = location where to put the data (512 bytes)
; dl  = drive, 0 = master, 1 = slave
push dx ; given gdt selector
mov dl, bl
  test eax, 0xF0000000	; test for bits 28-31
  jnz short .return_error
  test dl, 0xFE		; test for invalid device ids
  jnz short .return_error
  push edx
  push eax
  call ata_wait_not_busy

  mov dl, 0xF2		; port 0x1F2 (sector count register)
  mov al, 0x01		; read one sector at any given time
  out dx, al		;

  inc edx		; port 0x1F3 (sector number register)
  pop ecx		; set ecx = lba
  mov al, cl		; al = lba bits 0-7
  out dx, al		;

  inc edx		; port 0x1F4 (cylinder low register)
  mov al, ch		; al = lba bits 8-15
  out dx, al		;

  inc edx		; port 0x1F5 (cylinder high register)
  ror ecx, 16		;
  mov al, cl		; set al = lba bits 16-23
  out dx, al		;

  pop eax		; restore drive id
  inc edx		; port 0x1F6 (device/head register)
  and ch, 0x0F		; set ch = lba bits 24-27
  shl al, 4		; switch device id selection to bit 4
  or al, 0xE0		; set bit 7 and 5 to 1, with lba = 1
  or al, ch		; add in lba bits 24-27
  out dx, al		;

  call _wait_drdy	; wait for DRDY = 1 (Device ReaDY)
  test al, 0x10		; check DSC bit (Drive Seek Complete)
  jz short .return_error

  mov al, 0x20		; set al = read sector(s) (with retries)
  out dx, al		; edx = 0x1F7 == command/status register

  ; TODO: ask for thread yield, giving time for hdd to read data
  jmp short $+2
  jmp short $+2

  call ata_wait_not_busy.waiting	; bypass the "mov edx, 0x1F7"
  test al, 0x01     ; check for errors
  jnz short .return_error

  mov dl, 0xF0		; set dx = 0x1F0 (data register)
  mov ecx, 256		; 256 words (512 bytes)
cld
;==================================== I CHECKED THE EDI HERE - SET PROPERLY TO 0x210000 =================
;==================================== works well when edi is not higher then 0x210000, i guess ================
  repz insw		; read the sector to memory
  clc			; set completion flag to successful
pop dx
  ret			;

.return_error:
pop dx
mov ds, dx
mov esi, error_msg
call prints
  mov dl, 0xF1		; error status register 0x1F1
  in al, dx		; read error code
mov al, bl
mov eax, 8
int 0x80
  stc			; set completion flag to failed
  ret			;