source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/AH0h_HReset.asm@ 270

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

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Int 13h function AH=0h, Disk Controller Reset.
;
; 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 (in RAMVARS segment)
;       SS:BP:  Ptr to IDEPACK
;   Returns with INTPACK:
;       AH:     Int 13h return status (from drive requested in DL)
;       CF:     0 if succesfull, 1 if error
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
AH0h_HandlerForDiskControllerReset:
    eMOVZX  bx, dl                      ; Copy requested drive to BL, zero BH to assume no errors
    call    ResetFloppyDrivesWithInt40h

%ifdef MODULE_SERIAL_FLOPPY
;
; "Reset" emulatd 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.
        
    call    ResetForeignHardDisks

    ; Resetting our hard disks will modify dl and bl such that this call must be the last in the list
    ;
    call    AH0h_ResetHardDisksHandledByOurBIOS         

.SkipHardDiskReset:
    mov     ah, bh
    jmp     Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH


;--------------------------------------------------------------------
; 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     BIOS_DISKETTE_INTERRUPT_40h
    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
    call    Int13h_CallPreviousInt13hHandler
;;; fall-through to BackupErrorCodeFromTheRequestedDriveToBH


;--------------------------------------------------------------------
; 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?
    eCMOVE  bh, ah
    ret
        

;--------------------------------------------------------------------
; 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
    test    di, di
    jz      SHORT .Return               ; Return what was in BL unmodified
    mov     dl, 80h
.Return:
    ret


;--------------------------------------------------------------------
; AH0h_ResetHardDisksHandledByOurBIOS
;   Parameters:
;       BL:     Requested drive (DL when entering AH=00h)
;       DS:     RAMVARS segment
;       SS:BP:  Ptr to IDEPACK
;   Returns:
;       BH:     Error code from requested drive (if available)
;   Corrupts registers:
;       AX, CX, DX, SI, DI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
AH0h_ResetHardDisksHandledByOurBIOS:
    mov     bl, [di+DPT.bIdevarsOffset]                 ; replace drive number with Idevars pointer for cmp with dl
    mov     dl, ROMVARS.ideVars0                        ; starting Idevars offset

    call    RamVars_GetIdeControllerCountToCX
    jcxz    .done                                       ; just in case bIdeCnt is zero (shouldn't be)

    mov     si, IterateFindFirstDPTforIdevars           ; iteration routine (see below)

.loop:
    call    IterateAllDPTs                              ; look for the first drive on this controller, if any
    jc      .notFound

    call    AHDh_ResetDrive                             ; reset master and slave on that controller
    call    BackupErrorCodeFromTheRequestedDriveToBH    ; save error code if same controller as drive from entry

.notFound:
    add     dl, IDEVARS_size                            ; move Idevars pointer forward
    loop    .loop

.done:
    ret

;--------------------------------------------------------------------
; Iteration routine for AH0h_ResetHardDisksHandledByOurBIOS, 
; for use with IterateAllDPTs
; 
; Returns when DPT is found on the controller with Idevars offset in DL
;--------------------------------------------------------------------
IterateFindFirstDPTforIdevars:      
    cmp     dl, [di+DPT.bIdevarsOffset]         ; Clears CF if matched
    jz      .done
    stc                                         ; Set CF for not found
.done:  
    ret