source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/AH0h_HReset.asm

; Project name  :   XTIDE Universal BIOS
; Description   :   Int 13h function AH=0h, Disk Controller Reset.

;
; 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=0h, Disk Controller Reset.
;
; Note: We handle all AH=0h calls, even for drives handled by other
; BIOSes!
;
; AH0h_HandlerForDiskControllerReset
;   Parameters:
;       DL:     Translated Drive number (ignored so all drives are reset)
;               If bit 7 is set all hard disks and floppy disks reset.
;       DS:DI:  Ptr to DPT (or Null if foreign drive)
;       SS:BP:  Ptr to IDEPACK
;   Returns with INTPACK:
;       AH:     Int 13h return status (from drive requested in DL)
;       CF:     0 if successful, 1 if error
;--------------------------------------------------------------------
AH0h_HandlerForDiskControllerReset:
    ; Reset foreign Floppy and Hard Drives (those handled by other BIOSes)
    eMOVZX  bx, dl                                      ; Copy requested drive to BL and zero BH to assume no errors

    xor     ah, ah                                      ; Disk Controller Reset
    call    Int13h_CallPreviousInt13hHandler            ; Reset floppy drives only or floppy drives and foreign hard disks
    call    BackupErrorCodeFromTheRequestedDriveToBH

%ifdef MODULE_SERIAL_FLOPPY
;
; "Reset" emulated serial floppy drives, if any.  There is nothing to actually do for this reset,
; but record the proper error return code if one of these floppy drives is the drive requested.
;
    call    RamVars_UnpackFlopCntAndFirstToAL
    cbw                                                 ; Clears AH (there are flop drives) or ffh (there are not)
                                                        ; Either AH has success code (flop drives are present)
                                                        ; or it doesn't matter because we won't match drive ffh

    cwd                                                 ; clears DX (there are flop drives) or ffffh (there are not)

    adc     dl, al                                      ; second drive (CF set) if present
                                                        ; If no drive is present, this will result in ffh which
                                                        ; won't match a drive
    call    BackupErrorCodeFromTheRequestedDriveToBH
    mov     dl, al                                      ; We may end up doing the first drive twice (if there is
    call    BackupErrorCodeFromTheRequestedDriveToBH    ; only one drive), but doing it again is not harmful.
%endif
    test    bl, bl                                      ; If we were called with a floppy disk, then we are done,
    jns     SHORT .SkipHardDiskReset                    ; don't do hard disks.

    ; Resetting our hard disks will modify dl and bl to be idevars offset based instead of drive number based,
    ; such that this call must be the last in the list of reset routines called.
    ;
    ; This needs to happen after ResetForeignDrives, as that call may have set the error code for 80h,
    ; and we need to override that value if we are xlate'd into 80h with one of our drives.
    ;
    call    ResetHardDisksHandledByOurBIOS

.SkipHardDiskReset:
    mov     ah, bh
    jmp     Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH


;--------------------------------------------------------------------
; BackupErrorCodeFromTheRequestedDriveToBH
;   Parameters:
;       AH:     Error code from the last resetted drive
;       DL:     Drive last resetted
;       BL:     Requested drive (DL when entering AH=00h)
;   Returns:
;       BH:     Backuped error code
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
BackupErrorCodeFromTheRequestedDriveToBH:
    cmp     dl, bl              ; Requested drive?
    eCMOVE  bh, ah
    ret


;--------------------------------------------------------------------
; ResetHardDisksHandledByOurBIOS
;   Parameters:
;       BL:     Requested drive (DL when entering AH=00h)
;       DS:DI:  Ptr to DPT for requested drive
;               If DPT pointer is not available, or error result in BH won't be used anyway,
;               enter through .ErrorCodeNotUsed.
;       SS:BP:  Ptr to IDEPACK
;   Returns:
;       BH:     Error code from requested drive (if available)
;   Corrupts registers:
;       AX, BX, CX, DX, SI, DI
;--------------------------------------------------------------------
ResetHardDisksHandledByOurBIOS:
    xor     bl, bl                                      ; Assume Null IdevarsOffset for now, assuming foreign drive
    test    di, di
    jz      SHORT .ErrorCodeNotUsed
    mov     bl, [di+DPT.bIdevarsOffset]                 ; replace drive number with Idevars pointer for cmp with dl
.ErrorCodeNotUsed:                                      ; BH will be garbage on exit if this entry point is used,
                                                        ; but reset of all drives will still happen
    mov     dl, ROMVARS.ideVars0                        ; starting Idevars offset

    ; Get count of ALL Idevars structures, not just the ones that are configured.  This may seem odd,
    ; but it catches the .ideVarsSerialAuto structure, which would not be scanned if the count from
    ; RamVars_GetIdeControllerCountToCX was used.  Unused controllers won't make a difference, since no DPT
    ; will point to them.  Performance isn't an issue, as this is a reset operation.
    ;
    mov     cx, NUMBER_OF_IDEVARS

.Loop:
    call    FindDPT_MasterOrSingleForIdevarsOffsetInDL
    jc      SHORT .ControllerNotAvailable

    ; Reset controller (both Master and Slave Drive). We ignore error codes
    ; here since initialization is the one that matters.
    push    cx
    push    dx
    push    bx
%ifdef MODULE_IRQ
    call    Interrupts_UnmaskInterruptControllerForDriveInDSDI
%endif
    call    Device_ResetMasterAndSlaveController
%ifdef MODULE_ADVANCED_ATA
    call    AdvAtaInit_InitializeControllerForDPTinDSDI
%endif
    pop     bx
    pop     dx

    ; Initialize Master Drive
    call    AH9h_InitializeDriveForUse                  ; Initialize Master drive
    call    BackupErrorCodeFromTheRequestedDriveToBH

    ; Initialize Slave Drive
    call    FindDPT_SlaveForIdevarsOffsetInDL
    jc      SHORT .SlaveDriveNotAvailable
    call    AH9h_InitializeDriveForUse
    ; Here we have a small problem. Since DL now has offset to IDEVARS, it will be the same
    ; for both Master and Slave Drive. We simply ignore error from slave drive reset since most
    ; systems do not have slave drives at all and it is unlikely that AH=00h would be called for
    ; specific drive anyway. AH=Dh is for that.

.SlaveDriveNotAvailable:
    pop     cx
.ControllerNotAvailable:
    add     dl, IDEVARS_size                            ; move Idevars pointer forward
    loop    .Loop
    ret