source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/AH1Eh_XTCF.asm

; Project name  :   XTIDE Universal BIOS
; Description   :   Int 13h function AH=1Eh, Lo-tech XT-CF features
;
; More information at http://www.lo-tech.co.uk/XT-CF

;
; 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
;

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Int 13h function AH=1Eh, Lo-tech XT-CF features.
; This function is supported only by XTIDE Universal BIOS.
;
; AH1Eh_HandlerForXTCFfeatures
;   Parameters:
;       AL, CX: Same as in INTPACK
;       DL:     Translated Drive number
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;       SS:BP:  Ptr to IDEPACK
;   Parameters on INTPACK:
;       AL:     XT-CF subcommand (see XTCF.inc for more info)
;   Returns with INTPACK:
;       AH:     Int 13h return status
;       CF:     0 if successful, 1 if error
;       DX:     Command return values (see XTCF.inc)
;--------------------------------------------------------------------
AH1Eh_HandlerForXTCFfeatures:
%ifndef USE_186
    call    ProcessXTCFsubcommandFromAL
    jmp     Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH
%else
    push    Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH
    ; Fall to ProcessXTCFsubcommandFromAL
%endif


;--------------------------------------------------------------------
; ProcessXTCFsubcommandFromAL
;   Parameters:
;       AL:     XT-CF subcommand (see XTCF.inc for more info)
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;       SS:BP:  Ptr to IDEPACK
;   Returns:
;       AH:     Int 13h return status
;       CF:     0 if successful, 1 if error
;   Corrupts registers:
;       AL, BX, CX, DX, SI
;--------------------------------------------------------------------
ProcessXTCFsubcommandFromAL:
    ; IS_THIS_DRIVE_XTCF. We check this for all commands.
    call    AccessDPT_IsThisDeviceXTCF
    jc      SHORT .XTCFnotFound
    and     ax, 0FFh                    ; Subcommand now in AX (clears AH and CF)
    jz      SHORT .XTCFfound            ; Sub-function IS_THIS_DRIVE_XTCF (=0)

    dec     ax                          ; Test subcommand...
    jz      SHORT .SetXTCFtransferMode  ; ...for value 1 (SET_XTCF_TRANSFER_MODE)

    dec     ax                          ; Test subcommand for value 2 (GET_XTCF_TRANSFER_MODE)
    jnz     SHORT .AH1Eh_LoadInvalidCommandToAHandSetCF

    ; GET_XTCF_TRANSFER_MODE
    call    AH1Eh_GetCurrentXTCFmodeToAX
    mov     dh, al
    mov     dl, [di+DPT_ATA.bBlockSize]
    mov     [bp+IDEPACK.intpack+INTPACK.dx], dx ; Return mode value (DH) and block size (DL) via INTPACK
.XTCFfound:
    ret     ; With AH and CF cleared

.XTCFnotFound:
.AH1Eh_LoadInvalidCommandToAHandSetCF:
    stc     ; Set carry flag since XT-CF not found or invalid subcommand
    mov     ah, RET_HD_INVALID
    ret

.SetXTCFtransferMode:
    mov     al, [bp+IDEPACK.intpack+INTPACK.dh] ; Get specified mode (eg XTCF_DMA_MODE)
    ; Fall to AH1Eh_ChangeXTCFmodeBasedOnModeInAL


;--------------------------------------------------------------------
; AH1Eh_ChangeXTCFmodeBasedOnModeInAL
;   Parameters:
;       AL:     XT-CF Mode (see XTCF.inc)
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;       SS:BP:  Ptr to IDEPACK
;   Returns:
;       AH:     Int 13h return status
;       CF:     0 if successful, 1 if error
;   Corrupts registers:
;       AL, BX, CX, DX, SI
;--------------------------------------------------------------------
AH1Eh_ChangeXTCFmodeBasedOnModeInAL:
    ; Note: Control register (as of XT-CFv3) is now a write-only register,
    ;       whose purpose is *only* to raise DRQ.  The register cannot be read.
    ;       Selected transfer mode is stored in BIOS variable (DPT_ATA.bDevice).

    ; Note that when selecting 'XTCF_8BIT_PIO_MODE_WITH_BIU_OFFLOAD' mode,
    ; the ATA device (i.e. CompactFlash card) will operate in 8-bit mode, but
    ; data will be transferred from its data register using 16-bit CPU instructions
    ; like REP INSW.  This works because XT-CF adapters are 8-bit cards, and
    ; the BIU in the machine splits each WORD requested by the CPU into two 8-bit
    ; ISA cycles at base+0h and base+1h.  The XT-CF cards do not decode A0, hence
    ; both accesses appear the same to the card and the BIU then re-constructs
    ; the data for presentation to the CPU.
    ;
    ; Also note that some machines, noteably the Olivetti M24 (also known as
    ; the AT&T PC6300 or Xerox 6060 or Logabax Persona 1600), have hardware errors
    ; in the BIU logic, resulting in reversed byte ordering.  Therefore,
    ; XTCF_8BIT_PIO_MODE is the default transfer mode for best system compatibility.


    ; Is requested mode valid?
    cmp     al, 3                       ; Valid modes are 0...3
    ja      SHORT ProcessXTCFsubcommandFromAL.AH1Eh_LoadInvalidCommandToAHandSetCF

    ; Convert mode to XT-CF device type (see RomVars.inc and XTCF.inc for full details)
    eSHL_IM al, 1                       ; Shift requested mode
    add     al, XTCF_DEVICE_OFFSET      ; Add the device offset (already shifted)
    mov     [di+DPT_ATA.bDevice], al    ; Set the new mode (or device actually)

    cmp     al, DEVICE_8BIT_XTCF_PIO16_WITH_BIU_OFFLOAD
    je      SHORT AH23h_Disable8bitPioMode

    ; We always need to enable 8-bit mode since 16-bit mode is restored
    ; when controller is reset (AH=00h or 0Dh)

    cmp     al, DEVICE_8BIT_XTCF_DMA
    jne     SHORT AH23h_Enable8bitPioMode

    ; DMA transfers have limited block size
    mov     al, XTCF_DMA_MODE_MAX_BLOCK_SIZE
    cmp     [di+DPT_ATA.bBlockSize], al
    jbe     SHORT AH23h_Enable8bitPioMode   ; No need to limit block size
    call    AH24h_SetBlockSize
    jmp     SHORT AH23h_Enable8bitPioMode


;--------------------------------------------------------------------
; AH1Eh_GetCurrentXTCFmodeToAX
;   Parameters:
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;   Returns:
;       AX:     XT-CF mode (see XTCF.inc)
;       CF:     Clear
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
AH1Eh_GetCurrentXTCFmodeToAX:
    mov     ax, -XTCF_DEVICE_OFFSET & 0FFh
    add     al, [di+DPT_ATA.bDevice]
    shr     al, 1
    ret