source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/AHDh_HReset.asm @ 271

; Project name  :   XTIDE Universal BIOS
; Description   :   Int 13h function AH=Dh, Reset Hard Disk (Alternate reset).

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Int 13h function AH=Dh, Reset Hard Disk (Alternate reset).
;
; AHDh_HandlerForResetHardDisk
;   Parameters:
;       DL:     Translated Drive number
;       DS:DI:  Ptr to DPT (in RAMVARS segment)
;       SS:BP:  Ptr to IDEPACK
;   Returns with INTPACK:
;       AH:     Int 13h return status
;       CF:     0 if succesfull, 1 if error
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
AHDh_HandlerForResetHardDisk:
%ifndef USE_186
    call    AHDh_ResetDrive
    jmp     Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH
%else
    push    Int13h_ReturnFromHandlerAfterStoringErrorCodeFromAH
    ; Fall to AHDh_ResetDrive
%endif


;--------------------------------------------------------------------
; Resets hard disk.
;
; AHDh_ResetDrive
;   Parameters:
;       DS:DI:  Ptr to DPT
;       SS:BP:  Ptr to IDEPACK
;   Returns:
;       AH:     Int 13h return status
;       CF:     0 if succesfull, 1 if error
;   Corrupts registers:
;       AL, SI
;--------------------------------------------------------------------
AHDh_ResetDrive:
    push    dx
    push    cx
    push    bx
    push    di

    call    Interrupts_UnmaskInterruptControllerForDriveInDSDI
    call    Device_ResetMasterAndSlaveController
    ;jc     SHORT .ReturnError                  ; CF would be set if slave drive present without master
                                                ; (error register has special values after reset)

    ; Initialize Master and Slave drives
    mov     al, [di+DPT.bIdevarsOffset]         ; pointer to controller we are looking to reset
    mov     ah, 0                               ; initialize error code, assume success
        
    mov     si, IterateAndResetDrives
    call    FindDPT_IterateAllDPTs

    shr     ah, 1                               ; Move error code and CF into proper position

    pop     di
    pop     bx
    pop     cx
    pop     dx
    ret

;--------------------------------------------------------------------
; IterateAndResetDrives: Iteration routine for use with IterateAllDPTs.
;
; When a drive on the controller is found, it is reset, and the error code 
; merged into overall error code for this controller.  Master will be reset
; first.  Note that the iteration will go until the end of the DPT list.
;--------------------------------------------------------------------
IterateAndResetDrives:
    cmp     al, [di+DPT.bIdevarsOffset]         ; The right controller?
    jne     .done
    push    ax
    call    AH9h_InitializeDriveForUse          ; Reset Master and Slave (Master will come first in DPT list)
    pop     ax      
    jc      .done
    or      ah, (RET_HD_RESETFAIL << 1) | 1     ; OR in Reset Failed error code and CF, will SHR into position later
.done:
    stc                                         ; From IterateAllDPTs perspective, the DPT is never found (continue iteration)
    ret