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page 80,132
title CP/DOS DosSetSigHandler mapper
include msc.inc
dosxxx segment byte public 'dos'
assume cs:dosxxx,ds:nothing,es:nothing,ss:nothing
;**********************************************************************
;*
;* MODULE: dossetsighandler
;*
;* FILE NAME: dos007.asm
;*
;* CALLING SEQUENCE:
;*
;* push word file handle
;* push dword distance
;* push word move type
;* push@ dword new pointer
;* call doschgfileptr
;*
;* MODULES CALLED: PC-DOS Int 21h, ah=42h
;*
;*********************************************************************
public dossetsighandler
.sall
.xlist
include macros.inc
.list
str struc
old_bp dw ?
return dd ?
Signumber dw ? ; signal number
Action dw ? ; action code
Prevaction dd ? ; previous action code
Prevadrs dd ? ; previous vector address
Routineadrs dd ? ; interrupt handler address
str ends
; While we hate to do this, we have to. The following data areas are
; expected to be in the CODE segment.
NextControlBreakHandler label dword
NextControlBreakHandlerOffset dw DummyControlBreakHandler
NextControlBreakHandlerSegment dw dosxxx
NextCriticalErrorHandler label dword
NextCriticalErrorHandlerOffset dw DummyCriticalErrorHandler
NextCriticalErrorHandlerSegment dw dosxxx
dossetsighandler proc far
Enter dossetsighandler ; push registers
mov ax,[bp].action ; get action code
cmp ax,2 ; action code 2 ??
je continue1 ; branch if true
mov ax,1 ; else, set error code
jmp exit ; return
continue1:
mov ax,[bp].signumber ; get signel number
cmp ax,1 ; signal 1 (cntrl chara) ??
je cntrlc ; jump if true
cmp ax,4 ; signal 4 (cntrl chara) ??
je cntrlc ; jump if true
mov ax,2 ; else, set error code
jmp exit ; return
cntrlc: mov ax,03523h
int 21h ; get old vector address
lds si,[bp].prevadrs ; previous handler pointer
mov word ptr [si],bx ; save it in prevsdrs
mov word ptr [si]+2,es
lds dx,[bp].routineadrs ; get address of signal handler
mov NextControlBreakHandlerOffset,dx ; save it
mov NextControlBreakHandlerSegment,ds
mov dx,cs
mov ds,dx
mov dx,offset RealControlBreakHandler
mov ax,02523H
int 21h ; set signal handler addrs in vector
sub ax,ax ; set good return code
exit: mexit ; pop registers
ret size str - 6 ; return
dossetsighandler endp
page
;------------------------------------------------------------------------------
; This routine will get control on control break, and it will make
; sure that the environment is acceptable prior to calling the new
; handler. NOTE: we expect the new handler to be written in MicroSoft 'C'
RealControlBreakHandler proc far
push ds
push es
push di
push si
push bp
push dx
push cx
push bx
push ax
; reestablish the es and ds segment registers before going to 'C'
mov ax,seg DGroup
mov ds,ax
mov es,ax
call NextControlBreakHandler
pop ax
pop bx
pop cx
pop dx
pop bp
pop si
pop di
pop es
pop ds
iret
RealControlBreakHandler endp
page
;------------------------------------------------------------------------------
; This routine will get control on the control break, and it will make
; sure that the environment is acceptable prior to calling the new
; handler. NOTE: we expect the new handler to be written in MicroSoft 'C'
RealCriticalErrorHandler proc far
push ds
push es
push di
push si
push bp
push dx
push cx
push bx
push ax
; reestablish the es and ds segment registers before going to 'C'
mov ax,seg DGroup
mov ds,ax
mov es,ax
call NextControlBreakHandler
pop ax
pop bx
pop cx
pop dx
pop bp
pop si
pop di
pop es
pop ds
iret
RealCriticalErrorHandler endp
page
;------------------------------------------------------------------------------
DummyControlBreakHandler proc far
iret
DummyControlBreakHandler endp
DummyCriticalErrorHandler proc far
iret
DummyCriticalErrorHandler endp
dosxxx ends
end
|
