source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/AH24h_HSetBlocks.asm @ 148

; Project name  :   XTIDE Universal BIOS
; Description   :   Int 13h function AH=24h, Set Multiple Blocks.

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Int 13h function AH=24h, Set Multiple Blocks.
;
; AH24h_HandlerForSetMultipleBlocks
;   Parameters:
;       AL:     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:     Number of Sectors per Block (1, 2, 4, 8, 16, 32, 64 or 128)
;   Returns with INTPACK in SS:BP:
;       AH:     Int 13h return status
;       CF:     0 if succesfull, 1 if error
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
AH24h_HandlerForSetMultipleBlocks:
%ifndef USE_186
    call    AH24h_SetBlockSize
    jmp     Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH
%else
    push    Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH
    ; Fall through to AH24h_SetBlockSize
%endif


;--------------------------------------------------------------------
; Sets block size for block mode transfers.
;
; AH24h_SetBlockSize
;   Parameters:
;       AL:     Number of Sectors per Block (1, 2, 4, 8, 16, 32, 64 or 128)
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;   Returns:
;       AH:     Int 13h return status
;       CF:     0 if succesfull, 1 if error
;   Corrupts registers:
;       AL, BX, CX, DX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
AH24h_SetBlockSize:
    ; Select Master or Slave and wait until ready
    mov     bl, al                              ; Backup block size
    call    HDrvSel_SelectDriveAndDisableIRQ    ; Select drive and wait until ready
    jc      SHORT .ReturnWithErrorCodeInAH      ; Return if error

    ; Output block size and command
    mov     al, bl                              ; Restore block size to AL
    mov     ah, HCMD_SET_MUL                    ; Load command to AH
    mov     dx, [RAMVARS.wIdeBase]              ; Load base port address
    add     dx, BYTE REG_IDE_CNT
    call    HCommand_OutputSectorCountAndCommand
    call    HStatus_WaitBsyDefTime              ; Wait until drive not busy
    jc      SHORT .DisableBlockMode

    ; Store new block size to DPT and return
    mov     [di+DPT.bSetBlock], bl              ; Store new block size
    xor     ah, ah                              ; Zero AH and CF since success
    ret
.DisableBlockMode:
    mov     BYTE [di+DPT.bSetBlock], 1          ; Disable block mode
.ReturnWithErrorCodeInAH:
    ret