source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Device/IDE/JrIdeTransfer.asm@ 537

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

;
; XTIDE Universal BIOS and Associated Tools
; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team.
;
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation; either version 2 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
; GNU General Public License for more details.
; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
;

; Structure containing variables for PIO transfer functions.
; This struct must not be larger than IDEPACK without INTPACK.
struc MEMPIOVARS    ; Must not be larger than 9 bytes! See IDEPACK in RamVars.inc.
    .wSectorsInBlock        resb    2   ; 0-1, Block size in sectors
    .fpDPT                  resb    4   ; 2-5, Far pointer to DPT
    .bSectorsLeft           resb    1   ; 6, Sectors left to transfer
                            resb    1   ; 7, IDEPACK.bDeviceControl
    .bSectorsDone           resb    1   ; 8, Number of sectors xferred
endstruc


; Section containing code
SECTION .text

;--------------------------------------------------------------------
; JrIdeTransfer_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 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
JrIdeTransfer_StartWithCommandInAL:
    ; Initialize MEMPIOVARS
    xchg    cx, ax          ; IDE command to CL
    xor     ax, ax
    mov     [bp+MEMPIOVARS.bSectorsDone], al
    mov     al, [bp+IDEPACK.bSectorCount]
    mov     [bp+MEMPIOVARS.bSectorsLeft], al
    mov     al, [di+DPT_ATA.bBlockSize]
    mov     [bp+MEMPIOVARS.wSectorsInBlock], ax
    mov     [bp+MEMPIOVARS.fpDPT], di
    mov     [bp+MEMPIOVARS.fpDPT+2], ds

    ; Normalize pointer
    call    IdeTransfer_NormalizePointerInESSI

    ; Get far pointer to Sector Access Window
    mov     dx, [di+DPT.wBasePort]
    cmp     BYTE [di+DPT_ATA.bDevice], DEVICE_8BIT_JRIDE_ISA
    jb      SHORT .GetSectorAccessWindowForXTCF

    ; Get Sector Access Window for JR-IDE/ISA and ADP50L
    mov     ds, dx      ; Segment for JR-IDE/ISA and ADP50L
    mov     di, JRIDE_SECTOR_ACCESS_WINDOW_OFFSET
    je      SHORT .SectorAccessWindowLoadedToDSDI
    mov     di, ADP50L_SECTOR_ACCESS_WINDOW_OFFSET
    jmp     SHORT .SectorAccessWindowLoadedToDSDI

.GetSectorAccessWindowForXTCF:
    xor     di, di
    add     dl, XTCF_CONTROL_REGISTER
    in      al, dx                  ; Read high byte for Sector Access Window segment
    xchg    ah, al
    mov     ds, ax

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

;--------------------------------------------------------------------
; ReadFromSectorAccessWindow
;   Parameters:
;       DS:DI:  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 successful
;               1 if any error
;   Corrupts registers:
;       AL, BX, DX, SI
;--------------------------------------------------------------------
ReadFromSectorAccessWindow:
    xchg    si, di  ; DS:SI = source, ES:DI = Destination
    call    WaitUntilReadyToTransferNextBlock
    jc      SHORT ReturnWithMemoryIOtransferErrorInAH

    mov     cx, [bp+MEMPIOVARS.wSectorsInBlock] ; Clears CH
    cmp     [bp+MEMPIOVARS.bSectorsLeft], cl
    jbe     SHORT .ReadLastBlockFromDrive

ALIGN JUMP_ALIGN
.ReadNextBlockFromDrive:
    call    ReadSingleBlockFromSectorAccessWindowInDSSItoESDI
    call    WaitUntilReadyToTransferNextBlock
    jc      SHORT ReturnWithMemoryIOtransferErrorInAH

    ; Update number of successfully read sectors and sectors left to transfer.
    ; We cannot use SUB instruction as a comparison since it will not
    ; work in this situation:
    ; Before SUB we have 2 full blocks left to transfer. SUB command
    ; then compares 2 full blocks against one full block and updates
    ; sectors left to one full block and jumps to .ReadNextBlockFromDrive,
    ; since we have one full block left to transfer. After it has been
    ; transferred, there will be a wait for next block but DRQ is never
    ; set since all is transferred! Then we get timeout error.
    mov     cx, [bp+MEMPIOVARS.wSectorsInBlock]
    sub     [bp+MEMPIOVARS.bSectorsLeft], cl
    add     [bp+MEMPIOVARS.bSectorsDone], cl
    cmp     [bp+MEMPIOVARS.bSectorsLeft], cl
    ja      SHORT .ReadNextBlockFromDrive

ALIGN JUMP_ALIGN
.ReadLastBlockFromDrive:
    mov     cl, [bp+MEMPIOVARS.bSectorsLeft]
    push    cx
    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_BSY)
    call    IdeWait_PollStatusFlagInBLwithTimeoutInBH
    pop     cx  ; [bp+MEMPIOVARS.bSectorsLeft]
    jc      SHORT ReturnWithMemoryIOtransferErrorInAH

    ; All sectors successfully transferred
    add     cl, [bp+MEMPIOVARS.bSectorsDone]    ; Never sets CF
    ret

    ; Return number of successfully transferred sectors
ReturnWithMemoryIOtransferErrorInAH:
    lds     di, [bp+MEMPIOVARS.fpDPT]           ; DPT now in DS:DI
%ifdef USE_386
    movzx   cx, BYTE [bp+MEMPIOVARS.bSectorsDone]
%else
    mov     ch, 0                               ; Preserve CF
    mov     cl, [bp+MEMPIOVARS.bSectorsDone]
%endif
    ret


;--------------------------------------------------------------------
; WriteToSectorAccessWindow
;   Parameters:
;       DS:DI:  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 successful
;               1 if any error
;   Corrupts registers:
;       AL, BX, DX, SI, ES
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
WriteToSectorAccessWindow:
    push    es
    push    ds
    pop     es      ; ES:DI = Sector Access Window (destination)
    pop     ds      ; DS:SI = Ptr to source buffer

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

    mov     cx, [bp+MEMPIOVARS.wSectorsInBlock]
    cmp     [bp+MEMPIOVARS.bSectorsLeft], cl
    jbe     SHORT .WriteLastBlockToDrive

ALIGN JUMP_ALIGN
.WriteNextBlockToDrive:
    call    WriteSingleBlockFromDSSIToSectorAccessWindowInESDI
    call    WaitUntilReadyToTransferNextBlock
    jc      SHORT ReturnWithMemoryIOtransferErrorInAH

    ; Increment number of successfully written WORDs
    mov     cx, [bp+MEMPIOVARS.wSectorsInBlock]
    sub     [bp+MEMPIOVARS.bSectorsLeft], cl
    add     [bp+MEMPIOVARS.bSectorsDone], cl
    cmp     [bp+MEMPIOVARS.bSectorsLeft], cl
    ja      SHORT .WriteNextBlockToDrive

ALIGN JUMP_ALIGN
.WriteLastBlockToDrive:
    mov     cl, [bp+MEMPIOVARS.bSectorsLeft]
    push    cx
    ePUSH_T bx, CheckErrorsAfterTransferringLastMemoryMappedBlock
    ; Fall to WriteSingleBlockFromDSSIToSectorAccessWindowInESDI

;--------------------------------------------------------------------
; WriteSingleBlockFromDSSIToSectorAccessWindowInESDI
;   Parameters:
;       CX:     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
    mov     dx, cx
    xor     cx, cx
ALIGN JUMP_ALIGN
.WriteNextSector:
    inc     ch
    rep movsw
    mov     di, bx  ; Reset for next sector
    dec     dx
    jnz     SHORT .WriteNextSector
    ret


;--------------------------------------------------------------------
; ReadSingleBlockFromSectorAccessWindowInDSSItoESDI
;   Parameters:
;       CX      Number of sectors in full block or sectors in last partial 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
    mov     dx, cx
    xor     cx, cx
ALIGN JUMP_ALIGN
.ReadNextSector:
    inc     ch
    rep movsw
    mov     si, bx  ; Reset for next sector
    dec     dx
    jnz     SHORT .ReadNextSector
    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    IdeWait_IRQorDRQ            ; Always polls
    pop     di
    pop     ds
    ret