source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Device/IDE/IdeTransfer.asm@ 567

; Project name  :   XTIDE Universal BIOS
; Description   :   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 PIOVARS   ; Must not be larger than 9 bytes! See IDEPACK in RamVars.inc.
    .wDataPort              resb    2   ; 0-1, IDE Data Port
    .fnXfer                 resb    2   ; 2-3, Offset to transfer function
    .wSectorsInBlock        resb    2   ; 4-5, Block size in sectors
    .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

;--------------------------------------------------------------------
; IdeTransfer_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
IdeTransfer_StartWithCommandInAL:
    ; 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
    mov     ah, [bp+IDEPACK.bSectorCount]
    jnz     SHORT WriteToDrive
    cmp     al, COMMAND_WRITE_MULTIPLE
    je      SHORT WriteToDrive
    ; Fall to ReadFromDrive

;--------------------------------------------------------------------
; ReadFromDrive
;   Parameters:
;       AH:     Number of sectors to transfer (1...128)
;       ES:SI:  Ptr to buffer to receive data
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;       SS:BP:  Ptr to PIOVARS
;   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
;--------------------------------------------------------------------
ReadFromDrive:
    ; Prepare to read data to ESSI
    mov     bx, g_rgfnPioRead
    call    InitializePiovarsInSSBPwithSectorCountInAH
%ifdef USE_AT
    jc      SHORT ReturnWithTransferErrorInAH
%endif

    ; Wait until drive is ready to transfer
    call    IdeWait_IRQorDRQ                    ; Wait until ready to transfer
    jc      SHORT ReturnWithTransferErrorInAH
    xchg    si, di                              ; ES:DI now points buffer

    mov     cx, [bp+PIOVARS.wSectorsInBlock]    ; Max 128

ALIGN JUMP_ALIGN
.ReadNextBlockFromDrive:
    mov     dx, [bp+PIOVARS.wDataPort]
    cmp     [bp+PIOVARS.bSectorsLeft], cl
    jbe     SHORT .ReadLastBlockFromDrive
    call    [bp+PIOVARS.fnXfer]

    ; Wait until ready for next block and check for errors
    xchg    di, si                              ; DS:DI now points DPT
    call    IdeWait_IRQorDRQ                    ; Wait until ready to transfer
    jc      SHORT ReturnWithTransferErrorInAH
    xchg    si, di                              ; ES:DI now points buffer

    ; Increment number of successfully read sectors
    mov     cx, [bp+PIOVARS.wSectorsInBlock]
    sub     [bp+PIOVARS.bSectorsLeft], cl
    add     [bp+PIOVARS.bSectorsDone], cl
    jmp     SHORT .ReadNextBlockFromDrive

ALIGN JUMP_ALIGN
.ReadLastBlockFromDrive:
    mov     cl, [bp+PIOVARS.bSectorsLeft]       ; CH is already zero
    push    cx
    call    [bp+PIOVARS.fnXfer]                 ; Transfer possibly partial block

    ; Check for errors in last block
    mov     di, si                              ; DS:DI now points DPT
CheckErrorsAfterTransferringLastBlock:
    mov     bx, TIMEOUT_AND_STATUS_TO_WAIT(TIMEOUT_DRQ, FLG_STATUS_BSY)
    call    IdeWait_PollStatusFlagInBLwithTimeoutInBH
    pop     cx  ; [bp+PIOVARS.bSectorsLeft]
    jc      SHORT ReturnWithTransferErrorInAH

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

    ; Return number of successfully read sectors
ReturnWithTransferErrorInAH:
%ifdef USE_386
    movzx   cx, [bp+PIOVARS.bSectorsDone]
%else
    mov     cl, [bp+PIOVARS.bSectorsDone]
    mov     ch, 0                               ; Preserve CF
%endif
    ret


;--------------------------------------------------------------------
; WriteToDrive
;   Parameters:
;       AH:     Number of sectors to transfer (1...128)
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;       ES:SI:  Ptr to buffer containing data
;       SS:BP:  Ptr to PIOVARS
;   Returns:
;       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
WriteToDrive:
    ; Prepare to write data from ESSI
    mov     bx, g_rgfnPioWrite
    call    InitializePiovarsInSSBPwithSectorCountInAH
%ifdef USE_AT
    jc      SHORT ReturnWithTransferErrorInAH
%endif

    ; Always poll when writing first block (IRQs are generated for following blocks)
    mov     bx, TIMEOUT_AND_STATUS_TO_WAIT(TIMEOUT_DRQ, FLG_STATUS_DRQ)
    call    IdeWait_PollStatusFlagInBLwithTimeoutInBH
    jc      SHORT ReturnWithTransferErrorInAH

    mov     cx, [bp+PIOVARS.wSectorsInBlock]    ; Max 128

ALIGN JUMP_ALIGN
.WriteNextBlockToDrive:
    mov     dx, [bp+PIOVARS.wDataPort]
    cmp     [bp+PIOVARS.bSectorsLeft], cl
    jbe     SHORT .WriteLastBlockToDrive
    call    [bp+PIOVARS.fnXfer]

    ; Wait until ready for next block and check for errors
    call    IdeWait_IRQorDRQ                    ; Wait until ready to transfer
    jc      SHORT ReturnWithTransferErrorInAH

    ; Increment number of successfully written sectors
    mov     cx, [bp+PIOVARS.wSectorsInBlock]
    sub     [bp+PIOVARS.bSectorsLeft], cl
    add     [bp+PIOVARS.bSectorsDone], cl
    jmp     SHORT .WriteNextBlockToDrive

ALIGN JUMP_ALIGN
.WriteLastBlockToDrive:
    mov     cl, [bp+PIOVARS.bSectorsLeft]       ; CH is already zero
    push    cx
%ifdef USE_186
    push    CheckErrorsAfterTransferringLastBlock
    jmp     [bp+PIOVARS.fnXfer]                 ; Transfer possibly partial block
%else
    call    [bp+PIOVARS.fnXfer]                 ; Transfer possibly partial block
    jmp     SHORT CheckErrorsAfterTransferringLastBlock
%endif


;--------------------------------------------------------------------
; InitializePiovarsInSSBPwithSectorCountInAH
;   Parameters:
;       AH:     Number of sectors to transfer (1...128)
;       BX:     Offset to transfer function lookup table
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;       ES:SI:  Ptr to data buffer
;       SS:BP:  Ptr to PIOVARS
;   Returns:
;       ES:SI:  Normalized pointer
;       AH:     INT 13h Error Code (only when CF set)
;       CF:     Set if failed to normalize pointer (segment overflow)
;               Cleared if success
;   Corrupts registers:
;       AL, BX, DX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
InitializePiovarsInSSBPwithSectorCountInAH:
    ; Store sizes and Data Port
    mov     [bp+PIOVARS.bSectorsLeft], ah
%ifdef USE_AT
    xchg    dx, ax
%endif
    mov     ax, [di+DPT.wBasePort]
    mov     [bp+PIOVARS.wDataPort], ax
    eMOVZX  ax, [di+DPT_ATA.bBlockSize]
    mov     [bp+PIOVARS.wSectorsInBlock], ax
    mov     [bp+PIOVARS.bSectorsDone], ah       ; Zero

    ; Get transfer function based on bus type
    mov     al, [di+DPT_ATA.bDevice]
    add     bx, ax
%ifdef MODULE_8BIT_IDE_ADVANCED
    cmp     al, DEVICE_8BIT_XTCF_DMA
%endif
    mov     ax, [cs:bx]                         ; Load offset to transfer function
    mov     [bp+PIOVARS.fnXfer], ax

    ; Normalize pointer for PIO-transfers and convert to physical address for DMA transfers
%ifdef MODULE_8BIT_IDE_ADVANCED
    jb      SHORT IdeTransfer_NormalizePointerInESSI

    ; Convert ES:SI to physical address
%ifdef USE_186
                        ; Bytes EU Cycles(286)
    mov     ax, es      ; 2     2
    rol     ax, 4       ; 3     9
    mov     dx, ax      ; 2     2
    and     ax, BYTE 0Fh; 3     3
    xor     dx, ax      ; 2     2
    add     si, dx      ; 2     2
    adc     al, ah      ; 2     2
    mov     es, ax      ; 2     2
    ;------------------------------------
                        ; 18    24
%else ; 808x
                        ; Bytes EU Cycles(808x)
    mov     al, 4       ; 2     4
    mov     dx, es      ; 2     2
    xchg    cx, ax      ; 1     3
    rol     dx, cl      ; 2     24
    mov     cx, dx      ; 2     2
    xchg    cx, ax      ; 1     3
    and     ax, BYTE 0Fh; 3     4
    xor     dx, ax      ; 2     3
    add     si, dx      ; 2     3
    adc     al, ah      ; 2     3
    mov     es, ax      ; 2     2
    ;------------------------------------
                        ; 21    53
;
; Judging by the Execution Unit cycle count the above block of code is
; apparently slower. However, the shifts and rotates in the block below
; execute faster than the Bus Interface Unit on an 8088 can fetch them,
; thus causing the EU to starve. The difference in true execution speed
; (if any) might not be worth the extra 5 bytes.
; In other words, we could use a real world test here.
;
%if 0
                        ; Bytes EU Cycles(808x/286)
    xor     dx, dx      ; 2     3/2
    mov     ax, es      ; 2     2/2
%rep 4
    shl     ax, 1       ; 8     8/8
    rcl     dx, 1       ; 8     8/8
%endrep
    add     si, ax      ; 2     3/2
    adc     dl, dh      ; 2     3/2
    mov     es, dx      ; 2     2/2
    ;------------------------------------
                        ; 26    29/26
%endif ; 0
%endif

    ret     ; With CF cleared (taken care of by the physical address conversion)
%endif ; MODULE_8BIT_IDE_ADVANCED
    ; Fall to IdeTransfer_NormalizePointerInESSI if no MODULE_8BIT_IDE_ADVANCED


;--------------------------------------------------------------------
; IdeTransfer_NormalizePointerInESSI
;   Parameters:
;       DH:     Number of sectors to transfer (when USE_AT defined)
;       ES:SI:  Ptr to be normalized
;   Returns:
;       ES:SI:  Normalized pointer (SI = 0...15)
;       AH:     INT 13h Error Code (when USE_AT defined and normalization was attempted)
;       CF:     Set if failed to normalize pointer (segment overflow)
;               Cleared if success
;   Corrupts registers:
;       AX, DX
;--------------------------------------------------------------------
IdeTransfer_NormalizePointerInESSI:
; Normalization can cause segment overflow if it is done when not needed
; (I don't know if any software calls with such seg:off address).
; This does not apply to XT systems since nothing will write to main BIOS ROM.
; On AT systems things are quite different, even in protected mode the address
; is passed in seg:offset form and HMA is accessible in real mode.
%ifdef USE_AT
    xor     dl, dl
    eSHL_IM dx, 1
    dec     dx      ; Prevents normalization when bytes + offset will be zero
    add     dx, si
    jc      SHORT .NormalizationRequired
    ret
.NormalizationRequired:
%endif ; USE_AT

    NORMALIZE_FAR_POINTER   es, si, ax, dx
%ifdef USE_AT       ; CF is always clear for XT builds
    ; AH = RET_HD_INVALID (01) if CF set, RET_HD_SUCCESS (00) if not. CF unchanged.
    sbb     ah, ah
    neg     ah
%endif
    ret



; Lookup tables to get transfer function based on bus type
ALIGN WORD_ALIGN
g_rgfnPioRead:
        dw      IdePioBlock_ReadFrom16bitDataPort   ; 0, DEVICE_16BIT_ATA
        dw      IdePioBlock_ReadFrom32bitDataPort   ; 1, DEVICE_32BIT_ATA
%ifdef MODULE_8BIT_IDE
        dw      IdePioBlock_ReadFrom8bitDataPort    ; 2, DEVICE_8BIT_ATA
        dw      IdePioBlock_ReadFromXtideRev1       ; 3, DEVICE_8BIT_XTIDE_REV1
        dw      IdePioBlock_ReadFrom16bitDataPort   ; 4, DEVICE_8BIT_XTIDE_REV2
        dw      IdePioBlock_ReadFrom8bitDataPort    ; 5, DEVICE_8BIT_XTCF_PIO8
        dw      IdePioBlock_ReadFrom16bitDataPort   ; 6, DEVICE_8BIT_XTCF_PIO8_WITH_BIU_OFFLOAD
%ifdef MODULE_8BIT_IDE_ADVANCED
        dw      IdeDmaBlock_ReadFromXTCF            ; 7, DEVICE_8BIT_XTCF_DMA
%endif ; MODULE_8BIT_IDE_ADVANCED
%endif ; MODULE_8BIT_IDE


g_rgfnPioWrite:
        dw      IdePioBlock_WriteTo16bitDataPort    ; 0, DEVICE_16BIT_ATA
        dw      IdePioBlock_WriteTo32bitDataPort    ; 1, DEVICE_32BIT_ATA
%ifdef MODULE_8BIT_IDE
        dw      IdePioBlock_WriteTo8bitDataPort     ; 2, DEVICE_8BIT_ATA
        dw      IdePioBlock_WriteToXtideRev1        ; 3, DEVICE_8BIT_XTIDE_REV1
        dw      IdePioBlock_WriteToXtideRev2        ; 4, DEVICE_8BIT_XTIDE_REV2
        dw      IdePioBlock_WriteTo8bitDataPort     ; 5, DEVICE_8BIT_XTCF_PIO8
        dw      IdePioBlock_WriteTo16bitDataPort    ; 6, DEVICE_8BIT_XTCF_PIO8_WITH_BIU_OFFLOAD
%ifdef MODULE_8BIT_IDE_ADVANCED
        dw      IdeDmaBlock_WriteToXTCF             ; 7, DEVICE_8BIT_XTCF_DMA
%endif ; MODULE_8BIT_IDE_ADVANCED
%endif ; MODULE_8BIT_IDE