Category : Assembly Language Source Code
Archive   : STDLIB_A.ZIP
Filename : STRREV2.ASM

stdlib segment para public 'slcode'
assume cs:stdlib
;
extrn sl_malloc:far
;
;
; strrev2- reverses the characters in a string.
;
; inputs:
;
; ES:DI- Points at the string to reverse.
;
; outputs:
;
; ES:DI- Points at new string on the heap.
; Carry=1 if memory allocation error, 0 if no error.
;
;
; Created by Mike Blaszczak (.B ekiM) 8/8/90
; Some minor tweaking by R. Hyde 8/9/90
;
;
public sl_strrev2
;
;
sl_strrev2 proc far
push ds
push si
push ax
push cx
pushf
cld
;
;
; Compute the length (+1 for zero byte) of the string:
;
mov cx, 0ffffh
mov al, 0
repne scasb
neg cx
dec cx
;
; Save ptr to end of the string
;
mov si, es
mov ds, si
lea si, -1[di] ;Points at zero byte.
;
; Allocate storage for the new string:
;
mov ax, cx ;Save length
call sl_malloc
mov cx, ax ;Restore length
jc BadStrRev
push es ;Save ptr to string.
push di
;
; Note that string length is always at least one (for the zero byte).
; Copy and reverse the string down here.
;
CopyBytes: dec si
mov al, [si]
stosb
loop CopyBytes
mov byte ptr es:[di], 0
pop di ;Restore ptr to new string.
pop es
;
popf
pop cx
pop ax
pop si
pop ds
clc
ret
;
BadStrRev: popf
pop cx
pop ax
pop si
pop ds
stc
ret
sl_strrev2 endp
;
;
stdlib ends
end