source: xtideuniversalbios/tags/XTIDE_Universal_BIOS_v1.1.4/Src/Handlers/Int13h/AH23h_HFeatures.asm@ 462

; File name     :   AH23h_HFeatures.asm
; Project name  :   IDE BIOS
; Created date  :   28.12.2009
; Last update   :   12.4.2010
; Author        :   Tomi Tilli
; Description   :   Int 13h function AH=23h,
;                   Set Controller Features Register.

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Int 13h function AH=23h, Set Controller Features Register.
;
; AH23h_HandlerForSetControllerFeatures
;   Parameters:
;       AH:     Bios function 23h
;       AL:     Feature Number (parameter to Features Register = subcommand)
;       DL:     Drive number (8xh)
;   Parameters loaded by Int13h_Jump:
;       DS:     RAMVARS segment
;   Parameter registers are undocumented, specific for this BIOS:
;       BH:     Parameter to Sector Count Register (subcommand specific)
;       BL:     Parameter to Sector Number Register (subcommand specific)
;       CL:     Parameter to Low Cylinder Register (subcommand specific)
;       CH:     Parameter to High Cylinder Register (subcommand specific)
;   Returns:
;       AH:     Int 13h return status
;       CF:     0 if succesfull, 1 if error
;       IF:     1
;   Corrupts registers:
;       Flags
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
AH23h_HandlerForSetControllerFeatures:
    push    dx
    push    cx
    push    bx
    push    ax
    push    si

    ; Backup AL and BH to SI
    mov     ah, bh
    xchg    si, ax

    ; Select Master or Slave and wait until ready
    call    FindDPT_ForDriveNumber      ; DS:DI now points to DPT
    call    HDrvSel_SelectDriveAndDisableIRQ
    jc      SHORT .Return               ; Return if error

    ; Output Feature Number
    mov     ax, si                      ; Feature number to AL
    mov     dx, [RAMVARS.wIdeBase]      ; Load base port address
    inc     dx                          ; REGW_IDE_FEAT
    out     dx, al

    ; Output parameters to Sector Number Register and Cylinder Registers
    xor     bh, bh                      ; Zero head number
    dec     dx                          ; Back to base port address
    call    HCommand_OutputTranslatedLCHSaddress

    ; Output parameter to Sector Count Register and command
    xchg    ax, si                      ; Sector Count Reg param to AH
    mov     al, ah                      ; Sector Count Reg param to AL
    mov     ah, HCMD_SET_FEAT           ; Load Set Features command to AH
    call    HCommand_OutputSectorCountAndCommand

    call    HStatus_WaitBsyDefTime      ; Wait until drive ready
.Return:
    pop     si
    jmp     Int13h_PopXRegsAndReturn