source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/AH23h_HFeatures.asm @ 148

; Project name  :   XTIDE Universal BIOS
; 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:
;       AL, CX: Same as in INTPACK
;       DL:     Translated Drive number
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;       SS:BP:  Ptr to INTPACK
;   Parameters on INTPACK in SS:BP:
;       AL:     Feature Number (parameter to Features Register = subcommand)
;   (Parameter registers are undocumented, there are 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 with INTPACK in SS:BP:
;       AH:     Int 13h return status
;       CF:     0 if succesfull, 1 if error
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
AH23h_HandlerForSetControllerFeatures:
%ifndef USE_186
    call    AH23h_SetControllerFeatures
    jmp     Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH
%else
    push    Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH
    ; Fall through to AH23h_SetControllerFeatures
%endif


;--------------------------------------------------------------------
; AH23h_SetControllerFeatures
;   Parameters:
;       AL:     Feature Number (parameter to Features Register = subcommand)
;       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)
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;   Returns:
;       AH:     Int 13h return status
;       CF:     0 if succesfull, 1 if error
;   Corrupts registers:
;       AX, BX, CX, DX, SI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
AH23h_SetControllerFeatures:
    ; Backup AL and BH to SI
    mov     ah, bh
    xchg    si, ax

    ; Select Master or Slave and wait until ready
    call    HDrvSel_SelectDriveAndDisableIRQ
    jc      SHORT .ReturnWithErrorCodeInAH

    ; 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

    jmp     HStatus_WaitBsyDefTime      ; Wait until drive ready
.ReturnWithErrorCodeInAH:
    ret