Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/~phil/hardware/vertex/sharemegsvertex/lcu/pcr/c600/source/STARTUP/CHKSTK.ASM Дата изменения: Tue Mar 6 22:20:55 2001 Дата индексирования: Thu Jan 15 16:11:52 2009 Кодировка: Поисковые слова: ring

page ,132
title chkstk - C stack checking routine
;***
;chkstk.asm - C stack checking routine
;
; Copyright (c) 1985-1990 Microsoft Corporation, All Rights Reserved
;
;Purpose:
; Provides support for automatic stack checking in C procedures
; when stack checking is enabled.
;
;*******************************************************************************

.xlist
?PLM=0
?WIN=0

;
; The way this code is structured, the following switch combinations better
; not be defined.
;

;
; The USE_EXTERN flag indicates whether this module will be the default
; stack checking module for the library or not. If so, the stack checking
; data and subroutines must be defined. If not, the data and subroutines
; are NOT defined (i.e., they are externals that reside in the default
; stack checking object).
;
ifdef MI_NEAR
memS equ 1 ; near version
xchkstk equ <_aNchkstk>
ifdef mem_m ; if the default memory model is
USE_EXTERNS equ 1 ; medium or large, then use externs
endif ; in this module
ifdef mem_l
USE_EXTERNS equ 1
endif

elseifdef MI_FAR
memM equ 1 ; far version
xchkstk equ <_aFchkstk>
ifdef mem_s ; if the default memory model is
USE_EXTERNS equ 1 ; small or compact, then use externs
endif ; in this module
ifdef mem_c
USE_EXTERNS equ 1
endif

else
include version.inc ; default version
endif

include cmacros.inc
include msdos.inc

.list

sBegin data
assumes ds,data

extrn _end:word ; stack bottom

ifdef USE_EXTERNS
; Use the data that is in the default stack checking module.

if sizeC
externCP _aaltstkovr ; alternate stack overflow
endif

extrn STKHQQ:word

else ;not USE_EXTERNS

globalCP _aaltstkovr,-1 ; alternate stack overflow -- define always so
; mixed model works

public STKHQQ ; used by parasitic heap
ifdef FARSTACK
;far stack has bottom at 0
STKHQQ dw STACKSLOP ; initial value
else
STKHQQ dw dataoffset _end+STACKSLOP ; initial value
endif

endif ;not USE_EXTERNS

sEnd data


sBegin code
assumes ds,data
assumes cs,code

externNP _amsg_exit ; write error and die

page
;***
;_chkstk - check stack upon procedure entry
;
;Purpose:
; Provide stack checking on procedure entry.
;
; [LLIBCDLL.LIB NOTE: Unlike other LLIBCDLL routines, DS != DGROUP
; when chkstk() is called.]
;
;Entry:
; AX = size of local frame
;
;Exit:
; SP = new stackframe if successful
;
;Uses:
; AX, BX, CX, DX
;
;Exceptions:
; Gives out of memory error and aborts if there is not enough
; stack space for the routine.
;
;*******************************************************************************

ifndef USE_EXTERNS
; Define old label name in default model version
labelP
endif

% labelP

if sizeC
pop cx ; get return offset
pop dx ; get return segment
else
pop cx ; get return offset
endif

mov bx,sp ; bp = current SP


sub bx,ax ; bx = new position
jc OMerr ; error - out of memory



cmp bx,[STKHQQ] ; SP - AX : STKHQQ (for heap/stack)
jb OMerr ; error - out of memory
mov sp,bx ; set new stack pointer





if sizeC
push dx ; push segment
push cx ; push offset
chkproc proc far
ret ; far return to dx:cx
chkproc endp
else
jmp cx ; return to cx
endif

OMerr:
if sizeC
push dx ; user segment
endif
push cx ; user offset


if sizeC
mov ax,word ptr [_aaltstkovr]
inc ax
jnz altstkovr
endif


xor ax,ax
jmp _amsg_exit ; give stack overflow and die


if sizeC
altstkovr:
jmp [_aaltstkovr] ; Pascal/FORTRAN stack overflow
endif


sEnd code

end