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|
;
page 60,132
;
title CP/DOS DosReallocSeg mapper
;
dosxxx segment byte public 'dos'
assume cs:dosxxx,ds:nothing,es:nothing,ss:nothing
;
; ************************************************************************* *
; *
; * MODULE: DosReallocSeg
; *
; * FILE NAME: dos043.asm
; *
; * FUNCTION: This module changes the size of a segment already
; * allocated
; *
; * CALLING SEQUENCE:
; *
; * push size ; new segment size requested in bytes
; * push selector ; selector
; * call dosreallocseg
; *
; * RETURN SEQUENCE:
; *
; *
; *
; * MODULES CALLED: DOS Int 21, AH=4A
; *
; *
; *
; *************************************************************************
;
public dosreallocseg
.sall
.xlist
include macros.inc
.list
str struc
old_bp dw ?
return dd ?
Selector dw ? ; segment selector
SegmentSize dw ? ; new segment size in bytes
str ends
dosreallocseg proc far
Enter dosreallocseg ; save registers
mov bx,[bp].SegmentSize ; Get new segment size
cmp bx,0 ; check for 0
je AllocateMax ; jmp to full seg
shr bx,1 ; else convert segment in bytes
shr bx,1 ; paragraph
shr bx,1
shr bx,1
jmp HaveSize
AllocateMax:
mov bx,4096 ; default segment size in paragraph
HaveSize:
mov es,[bp].Selector ; set up segment for new size
mov ah,4ah ; set up for DOS realloc call
int 21h ; realloc segment
jc ErrorExit ; jump if error
sub ax,ax ; else set good return code
ErrorExit:
Mexit ; restore registers
ret size str - 6 ; return
dosreallocseg endp
dosxxx ends
end
|
