You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
143 lines
3.6 KiB
143 lines
3.6 KiB
page ,132
|
|
title memccpy - copy bytes until character found
|
|
;***
|
|
;memccpy.asm - copy bytes until a character is found
|
|
;
|
|
; Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
|
|
;
|
|
;Purpose:
|
|
; defines _memccpy() - copies bytes until a specifed character
|
|
; is found, or a maximum number of characters have been copied.
|
|
;
|
|
;Revision History:
|
|
; 05-16-84 RN initial version
|
|
; 05-17-88 SJM Add model-independent (large model) ifdef
|
|
; 08-04-88 SJM convert to cruntime/ add 32-bit support
|
|
; 08-23-88 JCR Minor 386 adjustments
|
|
; 10-25-88 JCR General cleanup for 386-only code
|
|
; 03-23-90 GJF Changed to _stdcall. Also, fixed the copyright.
|
|
; 01-17-91 GJF ANSI naming.
|
|
; 05-10-91 GJF Back to _cdecl, sigh...
|
|
; 10-27-92 SKS Avoid using a MASM keyword ("C") as a parameter name
|
|
; 01-19-95 GJF Faster version courtesy of Intel Israel.
|
|
; 01-24-95 GJF Added FPO directive.
|
|
; 06-12-01 PML inc->add 1, dec->sub 1 for Pentium 4 perf (vs7#267015)
|
|
;
|
|
;*******************************************************************************
|
|
|
|
.xlist
|
|
include cruntime.inc
|
|
.list
|
|
|
|
page
|
|
;***
|
|
;char *_memccpy(dest, src, _c, count) - copy bytes until character found
|
|
;
|
|
;Purpose:
|
|
; Copies bytes from src to dest until count bytes have been
|
|
; copied, or up to and including the character _c, whichever
|
|
; comes first.
|
|
;
|
|
; Algorithm:
|
|
; char *
|
|
; _memccpy (dest, src, _c, count)
|
|
; char *dest, *src, _c;
|
|
; unsigned int count;
|
|
; {
|
|
; while (count && (*dest++ = *src++) != _c)
|
|
; count--;
|
|
;
|
|
; return(count ? dest : NULL);
|
|
; }
|
|
;
|
|
;Entry:
|
|
; char *dest - pointer to memory to receive copy
|
|
; char *src - source of bytes
|
|
; char _c - character to stop copy at
|
|
; int count - max number of bytes to copy
|
|
;
|
|
;Exit:
|
|
; returns pointer to byte immediately after _c in dest;
|
|
; returns NULL if _c was never found
|
|
;
|
|
;Uses:
|
|
;
|
|
;Exceptions:
|
|
;
|
|
;*******************************************************************************
|
|
|
|
CODESEG
|
|
|
|
public _memccpy
|
|
_memccpy proc
|
|
|
|
.FPO ( 0, 4, 0, 0, 0, 0 )
|
|
|
|
mov ecx,[esp + 10h] ; ecx = max byte count
|
|
push ebx ; save ebx
|
|
|
|
test ecx,ecx ; if it's nothing to move
|
|
jz ret_zero_len ; restore ebx, and return NULL
|
|
|
|
mov bh,[esp + 10h] ; bh = byte to look for
|
|
push esi ; save esi
|
|
|
|
test ecx,1 ; test if counter is odd or even
|
|
|
|
mov eax,[esp + 0ch] ; eax = dest , don't affect flags
|
|
mov esi,[esp + 10h] ; esi = source , don't affect flags
|
|
|
|
; nop
|
|
jz lupe2 ; if counter is even, do double loop
|
|
; else do one iteration, and drop into double loop
|
|
mov bl,[esi] ; get first byte into bl
|
|
add esi,1 ; kick src (esi points to src)
|
|
|
|
mov [eax],bl ; store it in dest
|
|
add eax,1 ; kick dest
|
|
|
|
cmp bl,bh ; see if we just moved the byte
|
|
je short toend
|
|
|
|
sub ecx,1 ; decrement counter
|
|
jz retnull ; drop into double loop if nonzero
|
|
|
|
lupe2:
|
|
mov bl,[esi] ; get first byte into bl
|
|
add esi,2 ; kick esi (src)
|
|
|
|
cmp bl,bh ; check if we just moved the byte (from bl)
|
|
je toend_mov_inc ; store bl & exit
|
|
|
|
mov [eax],bl ; store first byte from bl
|
|
mov bl,[esi - 1] ; get second byte into bl
|
|
|
|
mov [eax + 1],bl ; store second byte from bl
|
|
add eax,2 ; kick eax (dest)
|
|
|
|
cmp bl,bh ; see if we just moved the byte
|
|
je short toend ; end of string
|
|
|
|
sub ecx,2 ; modify counter, and if nonzero continue
|
|
jnz lupe2 ; else drop out & return NULL
|
|
|
|
retnull:
|
|
pop esi
|
|
ret_zero_len:
|
|
xor eax,eax ; null pointer
|
|
pop ebx
|
|
|
|
ret ; _cdecl return
|
|
|
|
toend_mov_inc:
|
|
mov [eax],bl ; store first byte from bl
|
|
add eax,1 ; eax points right after the value
|
|
|
|
toend: pop esi
|
|
pop ebx
|
|
|
|
ret ; _cdecl return
|
|
|
|
_memccpy endp
|
|
|
|
end
|