source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/AH0h_HReset.asm@ 29

; File name     :   AH0h_HReset.asm
; Project name  :   IDE BIOS
; Created date  :   27.9.2007
; Last update   :   29.7.2010
; Author        :   Tomi Tilli
; Description   :   Int 13h function AH=0h, Disk Controller Reset.

RETRIES_IF_RESET_FAILS      EQU     3
TIMEOUT_BEFORE_RESET_RETRY  EQU     5       ; System timer ticks

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Int 13h function AH=0h, Disk Controller Reset.
;
; AH0h_HandlerForDiskControllerReset
;   Parameters:
;       AH:     Bios function 0h
;       DL:     Drive number (ignored so all drives are reset)
;               If bit 7 is set all hard disks and floppy disks reset.
;   Parameters loaded by Int13h_Jump:
;       DS:     RAMVARS segment
;   Returns:
;       AH:     Int 13h return status (from drive requested in DL)
;       CF:     0 if succesfull, 1 if error
;       IF:     1
;   Corrupts registers:
;       Flags
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
AH0h_HandlerForDiskControllerReset:
    push    dx
    push    cx
    push    bx
    push    ax

    eMOVZX  bx, dl                      ; Copy requested drive to BL, zero BH to assume no errors
    call    ResetFloppyDrivesWithInt40h
    test    bl, 80h
    jz      SHORT .SkipHardDiskReset
    call    ResetForeignHardDisks
    call    AH0h_ResetHardDisksHandledByOurBIOS
ALIGN JUMP_ALIGN
.SkipHardDiskReset:
    mov     ah, bh                      ; Copy error code to AH
    xor     al, al                      ; Zero AL...
    cmp     al, bh                      ; ...and set CF if error
    jmp     Int13h_StoreErrorCodeToBDAandPopXRegsAndReturn


;--------------------------------------------------------------------
; ResetFloppyDrivesWithInt40h
;   Parameters:
;       BL:     Requested drive (DL when entering AH=00h)
;   Returns:
;       BH:     Error code from requested drive (if available)
;   Corrupts registers:
;       AX, DL, DI
;--------------------------------------------------------------------   
ALIGN JUMP_ALIGN
ResetFloppyDrivesWithInt40h:
    call    GetDriveNumberForForeignBiosesToDL
    and     dl, 7Fh                     ; Clear hard disk bit
    xor     ah, ah                      ; Disk Controller Reset
    int     INTV_FLOPPY_FUNC
    jmp     SHORT BackupErrorCodeFromTheRequestedDriveToBH


;--------------------------------------------------------------------
; ResetForeignHardDisks
;   Parameters:
;       BL:     Requested drive (DL when entering AH=00h)
;       DS:     RAMVARS segment
;   Returns:
;       BH:     Error code from requested drive (if available)
;   Corrupts registers:
;       AX, DL, DI
;--------------------------------------------------------------------   
ALIGN JUMP_ALIGN
ResetForeignHardDisks:
    call    GetDriveNumberForForeignBiosesToDL
    xor     ah, ah                      ; Disk Controller Reset
    pushf                               ; Push flags to simulate INT
    cli                                 ; Disable interrupts since INT does that
    call    FAR [RAMVARS.fpOldI13h]
    sti                                 ; Make sure interrupts are enabled again (some BIOSes fails to enable it)
    jmp     SHORT BackupErrorCodeFromTheRequestedDriveToBH


;--------------------------------------------------------------------
; GetDriveNumberForForeignBiosesToDL
;   Parameters:
;       BL:     Requested drive (DL when entering AH=00h)
;       DS:     RAMVARS segment
;   Returns:
;       DL:     BL if foreign drive
;               80h if our drive
;   Corrupts registers:
;       DI
;--------------------------------------------------------------------   
ALIGN JUMP_ALIGN
GetDriveNumberForForeignBiosesToDL:
    mov     dl, bl
    call    RamVars_IsDriveHandledByThisBIOS
    jc      SHORT .GetFirstDriveForForeignBios
    ret     ; Return what was in BL unmodified
ALIGN JUMP_ALIGN
.GetFirstDriveForForeignBios:
    mov     dl, 80h
    ret


;--------------------------------------------------------------------
; ResetHardDisksHandledByOurBIOS
;   Parameters:
;       BL:     Requested drive (DL when entering AH=00h)
;       DS:     RAMVARS segment
;   Returns:
;       BH:     Error code from requested drive (if available)
;   Corrupts registers:
;       AX, CX, DX, DI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
AH0h_ResetHardDisksHandledByOurBIOS:
    mov     dh, [RAMVARS.bDrvCnt]       ; Load drive count to DH
    test    dh, dh
    jz      SHORT .AllDrivesReset       ; Return if no drives
    mov     dl, [RAMVARS.bFirstDrv]     ; Load number of first our drive
    add     dh, dl                      ; DH = one past last drive to reset
ALIGN JUMP_ALIGN
.DriveResetLoop:
    call    AHDh_ResetDrive
    call    .BackupErrorCodeFromMasterOrSlaveToBH
    inc     dx
    cmp     dl, dh                      ; All done?
    jb      SHORT .DriveResetLoop       ;  If not, reset next drive
.AllDrivesReset:
    ret

;--------------------------------------------------------------------
; .BackupErrorCodeFromMasterOrSlaveToBH
;   Parameters:
;       AH:     Error code for drive DL reset
;       BL:     Requested drive (DL when entering AH=00h)
;       DL:     Drive just resetted
;       DS:     RAMVARS segment
;   Returns:
;       BH:     Backuped error code
;       DL:     Incremented if next drive is slave drive
;               (=already resetted)
;   Corrupts registers:
;       CX, DI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
.BackupErrorCodeFromMasterOrSlaveToBH:
    call    BackupErrorCodeFromTheRequestedDriveToBH
    mov     cx, [RAMVARS.wIdeBase]      ; Load base port for resetted drive

    inc     dx                          ; DL to next drive
    call    FindDPT_ForDriveNumber      ; Get DPT to DS:DI, store port to RAMVARS
    jnc     SHORT .NoMoreDrivesOrNoSlaveDrive
    cmp     cx, [RAMVARS.wIdeBase]      ; Next drive is from same controller?
    je      SHORT BackupErrorCodeFromTheRequestedDriveToBH
.NoMoreDrivesOrNoSlaveDrive:
    dec     dx
    ret


;--------------------------------------------------------------------
; 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
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
BackupErrorCodeFromTheRequestedDriveToBH:
    cmp     dl, bl              ; Requested drive?
    jne     SHORT .Return
    mov     bh, ah
ALIGN JUMP_ALIGN
.Return:
    ret