source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Device/MemoryMappedIDE/MemIdeTransfer.asm @ 242

; Project name  :   XTIDE Universal BIOS
; Description   :   Memory mapped IDE Device transfer functions.

; Structure containing variables for PIO transfer functions.
; This struct must not be larger than IDEPACK without INTPACK.
struc MEMPIOVARS
    .wWordsInBlock          resb    2   ; 0, Block size in WORDs
    .wWordsLeft             resb    2   ; 2, WORDs left to transfer
    .wWordsDone             resb    2   ; 4, Number of sectors xferred
    ; TODO: The above word vars could just as well be byte vars?
                            resb    1   ; 6,
                            resb    1   ; 7, IDEPACK.bDeviceControl
    .fpDPT                  resb    4   ; 8, Far pointer to DPT
endstruc


; Section containing code
SECTION .text

;--------------------------------------------------------------------
; MemIdeTransfer_StartWithCommandInAL
;   Parameters:
;       AL:     IDE command that was used to start the transfer
;               (all PIO read and write commands including Identify Device)
;       ES:SI:  Ptr to normalized data buffer
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;       SS:BP:  Ptr to IDEPACK
;   Returns:
;       AH:     INT 13h Error Code
;       CX:     Number of successfully transferred sectors
;       CF:     Cleared if success, Set if error
;   Corrupts registers:
;       AL, BX, DX, SI, ES
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
MemIdeTransfer_StartWithCommandInAL:
    push    cs  ; We push CS here (segment of SAW) and later pop it to DS (reads) or ES (writes)

    ; Initialize MEMPIOVARS
    xor     cx, cx
    mov     [bp+MEMPIOVARS.wWordsDone], cx
    mov     ch, [bp+IDEPACK.bSectorCount]
    mov     [bp+MEMPIOVARS.wWordsLeft], cx
    mov     ch, [di+DPT_ATA.bSetBlock]
    mov     [bp+MEMPIOVARS.wWordsInBlock], cx
    mov     [bp+MEMPIOVARS.fpDPT], di
    mov     [bp+MEMPIOVARS.fpDPT+2], ds

    ; Are we reading or writing?
    test    al, 16  ; Bit 4 is cleared on all the read commands but set on 3 of the 4 write commands
    jnz     SHORT WriteToSectorAccessWindow
    cmp     al, COMMAND_WRITE_MULTIPLE
    je      SHORT WriteToSectorAccessWindow
    ; Fall to ReadFromSectorAccessWindow

;--------------------------------------------------------------------
; ReadFromSectorAccessWindow
;   Parameters:
;       Stack:  Segment part of ptr to Sector Access Window
;       ES:SI:  Normalized ptr to buffer to receive data
;       SS:BP:  Ptr to MEMPIOVARS
;   Returns:
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;       AH:     BIOS Error code
;       CX:     Number of successfully transferred sectors
;       CF:     0 if transfer succesfull
;               1 if any error
;   Corrupts registers:
;       AL, BX, DX, SI, ES
;--------------------------------------------------------------------
ReadFromSectorAccessWindow:
    pop     ds  ; CS -> DS
    mov     di, si
    mov     si, JRIDE_SECTOR_ACCESS_WINDOW_OFFSET

    call    WaitUntilReadyToTransferNextBlock
    jc      SHORT ReturnWithMemoryIOtransferErrorInAH

    mov     cx, [bp+PIOVARS.wWordsInBlock]

ALIGN JUMP_ALIGN
.ReadNextBlockFromDrive:
    cmp     [bp+PIOVARS.wWordsLeft], cx
    jbe     SHORT .ReadLastBlockFromDrive
    call    ReadSingleBlockFromSectorAccessWindowInDSSItoESDI
    call    WaitUntilReadyToTransferNextBlock
    jc      SHORT ReturnWithMemoryIOtransferErrorInAH

    ; Increment number of successfully read WORDs
    mov     cx, [bp+PIOVARS.wWordsInBlock]
    sub     [bp+PIOVARS.wWordsLeft], cx
    add     [bp+PIOVARS.wWordsDone], cx
    jmp     SHORT .ReadNextBlockFromDrive

ALIGN JUMP_ALIGN
.ReadLastBlockFromDrive:
    mov     ch, [bp+PIOVARS.wWordsLeft+1]       ; Sectors left
    call    ReadSingleBlockFromSectorAccessWindowInDSSItoESDI

    ; Check for errors in last block
CheckErrorsAfterTransferringLastMemoryMappedBlock:
    lds     di, [bp+MEMPIOVARS.fpDPT]           ; DPT now in DS:DI
    mov     bx, TIMEOUT_AND_STATUS_TO_WAIT(TIMEOUT_DRQ, FLG_STATUS_DRDY)
    call    IDEDEVICE%+Wait_PollStatusFlagInBLwithTimeoutInBH

    ; Return number of successfully transferred sectors
ReturnWithMemoryIOtransferErrorInAH:
    lds     di, [bp+MEMPIOVARS.fpDPT]           ; DPT now in DS:DI
    mov     cx, [bp+PIOVARS.wWordsDone]
    jc      SHORT .ConvertTransferredWordsInCXtoSectors
    add     cx, [bp+PIOVARS.wWordsLeft]         ; Never sets CF
.ConvertTransferredWordsInCXtoSectors:
    xchg    cl, ch
    ret


;--------------------------------------------------------------------
; WriteToSectorAccessWindow
;   Parameters:
;       Stack:  Segment part of ptr to Sector Access Window
;       ES:SI:  Normalized ptr to buffer containing data
;       SS:BP:  Ptr to MEMPIOVARS
;   Returns:
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;       AH:     BIOS Error code
;       CX:     Number of successfully transferred sectors
;       CF:     0 if transfer succesfull
;               1 if any error
;   Corrupts registers:
;       AL, BX, DX, SI, ES
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
WriteToSectorAccessWindow:
    push    es
    pop     ds
    pop     es  ; CS -> ES
    mov     di, JRIDE_SECTOR_ACCESS_WINDOW_OFFSET

    ; Always poll when writing first block (IRQs are generated for following blocks)
    call    WaitUntilReadyToTransferNextBlock
    jc      SHORT ReturnWithMemoryIOtransferErrorInAH

    mov     cx, [bp+PIOVARS.wWordsInBlock]

ALIGN JUMP_ALIGN
.WriteNextBlockToDrive:
    cmp     [bp+PIOVARS.wWordsLeft], cx
    jbe     SHORT .WriteLastBlockToDrive
    call    WriteSingleBlockFromDSSIToSectorAccessWindowInESDI
    call    WaitUntilReadyToTransferNextBlock
    jc      SHORT ReturnWithMemoryIOtransferErrorInAH

    ; Increment number of successfully written WORDs
    mov     cx, [bp+PIOVARS.wWordsInBlock]
    sub     [bp+PIOVARS.wWordsLeft], cx
    add     [bp+PIOVARS.wWordsDone], cx
    jmp     SHORT .WriteNextBlockToDrive

ALIGN JUMP_ALIGN
.WriteLastBlockToDrive:
    mov     ch, [bp+PIOVARS.wWordsLeft+1]       ; Sectors left
%ifndef USE_186
    mov     bx, CheckErrorsAfterTransferringLastMemoryMappedBlock
    push    bx
%else
    push    CheckErrorsAfterTransferringLastMemoryMappedBlock
%endif
    ; Fall to WriteSingleBlockFromDSSIToSectorAccessWindowInESDI

;--------------------------------------------------------------------
; WriteSingleBlockFromDSSIToSectorAccessWindowInESDI
;   Parameters:
;       CH:     Number of sectors in block
;       DS:SI:  Normalized ptr to source buffer
;       ES:DI:  Ptr to Sector Access Window
;   Returns:
;       CX, DX: Zero
;       SI:     Updated
;   Corrupts registers:
;       BX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
WriteSingleBlockFromDSSIToSectorAccessWindowInESDI:
    mov     bx, di
    eMOVZX  dx, ch
    xor     cl, cl
ALIGN JUMP_ALIGN
.WriteBlock:
    mov     ch, JRIDE_SECTOR_ACCESS_WINDOW_SIZE >> 9
    rep movsw
    mov     di, bx  ; Reset for next sector
    dec     dx
    jnz     SHORT .WriteBlock
    ret


;--------------------------------------------------------------------
; ReadSingleBlockFromSectorAccessWindowInDSSItoESDI
;   Parameters:
;       CH:     Number of sectors in block
;       ES:DI:  Normalized ptr to buffer to receive data (destination)
;       DS:SI:  Ptr to Sector Access Window (source)
;   Returns:
;       CX, DX: Zero
;       DI:     Updated
;   Corrupts registers:
;       BX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
ReadSingleBlockFromSectorAccessWindowInDSSItoESDI:
    mov     bx, si
    eMOVZX  dx, ch
    xor     cl, cl
ALIGN JUMP_ALIGN
.ReadBlock:
    mov     ch, JRIDE_SECTOR_ACCESS_WINDOW_SIZE >> 9
    rep movsw
    mov     si, bx  ; Reset for next sector
    dec     dx
    jnz     SHORT .ReadBlock
    ret


;--------------------------------------------------------------------
; WaitUntilReadyToTransferNextBlock
;   Parameters:
;       SS:BP:  Ptr to MEMPIOVARS
;   Returns:
;       AH:     INT 13h Error Code
;       CF:     Cleared if success, Set if error
;   Corrupts registers:
;       AL, BX, CX, DX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
WaitUntilReadyToTransferNextBlock:
    push    ds
    push    di
    lds     di, [bp+MEMPIOVARS.fpDPT]           ; DPT now in DS:DI
    call    IDEDEVICE%+Wait_IRQorDRQ            ; Always polls
    pop     di
    pop     ds
    ret


%if JRIDE_SECTOR_ACCESS_WINDOW_SIZE <> 512
    %error "JRIDE_SECTOR_ACCESS_WINDOW_SIZE is no longer equal to 512. MemIdeTransfer.asm needs changes."
%endif