source: xtideuniversalbios/trunk/Assembly_Library/Src/File/DosCritical.asm@ 592

; Project name  :   Assembly Library
; Description   :   DOS Critical Error Handler (24h) replacements.

;
; 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
;

; Note! Only DOS functions 01h - 0Ch, 30h and 59h can be called from a Critical Error Handler.

; DOS Critical Error Handler return values
struc CRITICAL_ERROR_ACTION
    .ignoreErrorAndContinueProcessingRequest    resb    1
    .retryOperation                             resb    1
    .terminateProgramAsThoughInt21hAH4ChCalled  resb    1
    .failSystemCallInProgress                   resb    1   ; Needs DOS 3.1+
endstruc


; Section containing code
SECTION .text

;--------------------------------------------------------------------
; DosCritical_InstallNewHandlerFromCSDX
;   Parameters:
;       CS:DX:  New Critical Error Handler
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
DosCritical_InstallNewHandlerFromCSDX:
    push    ds

    push    cs
    pop     ds
    mov     ax, (SET_INTERRUPT_VECTOR<<8) | DOS_CRITICAL_ERROR_HANDLER_24h
    int     DOS_INTERRUPT_21h

    pop     ds
    ret


;--------------------------------------------------------------------
; DosCritical_RestoreDosHandler
;   Parameters:
;       Nothing
;   Returns:
;       Nothing
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
DosCritical_RestoreDosHandler:
    push    ds
    push    dx
    push    ax

    lds     dx, [cs:PSP.fpInt24hCriticalError]
    mov     ax, (SET_INTERRUPT_VECTOR<<8) | DOS_CRITICAL_ERROR_HANDLER_24h
    int     DOS_INTERRUPT_21h

    pop     ax
    pop     dx
    pop     ds
    ret


;--------------------------------------------------------------------
; DosCritical_CustomHandler
;   Parameters:
;       Nothing
;   Returns:
;       Nothing
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
DosCritical_CustomHandler:
    add     sp, 6   ; Remove the INT 24h return address and flags from stack

    mov     ah, GET_EXTENDED_ERROR_INFORMATION  ; Requires DOS 3.0+
    xor     bx, bx
    int     DOS_INTERRUPT_21h
    mov     [cs:bLastCriticalError], al

    pop     ax
    pop     bx
    pop     cx
    pop     dx
    pop     si
    pop     di
    pop     bp
    pop     ds
    pop     es
    iret            ; Return from the INT 21h call

bLastCriticalError:     db  0


;--------------------------------------------------------------------
; DosCritical_HandlerToIgnoreAllErrors
;   Parameters:
;       Nothing
;   Returns:
;       AL:     CRITICAL_ERROR_ACTION
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
DosCritical_HandlerToIgnoreAllErrors:
    mov     al, CRITICAL_ERROR_ACTION.ignoreErrorAndContinueProcessingRequest
    iret