mirror of
https://sourceware.org/git/glibc.git
synced 2025-10-30 10:45:40 +03:00
83 lines
2.3 KiB
C
83 lines
2.3 KiB
C
/* bzero -- set a block of memory to zero. For Intel 80x86, x>=3.
|
|
This file is part of the GNU C Library.
|
|
Copyright (C) 1991,92,93,97,98,99, 05 Free Software Foundation, Inc.
|
|
Contributed by Torbjorn Granlund (tege@sics.se).
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
#include <string.h>
|
|
#include <memcopy.h>
|
|
|
|
#undef bzero
|
|
#undef __bzero
|
|
|
|
#ifdef __GNUC__
|
|
|
|
void
|
|
__bzero (dstpp, len)
|
|
void *dstpp;
|
|
size_t len;
|
|
{
|
|
/* N.B.: This code is almost verbatim from memset.c. */
|
|
int d0;
|
|
unsigned long int dstp = (unsigned long int) dstpp;
|
|
|
|
/* This explicit register allocation
|
|
improves code very much indeed. */
|
|
register op_t x asm ("ax");
|
|
|
|
x = 0;
|
|
|
|
/* Clear the direction flag, so filling will move forward. */
|
|
asm volatile ("cld");
|
|
|
|
/* This threshold value is optimal. */
|
|
if (len >= 12)
|
|
{
|
|
/* Adjust LEN for the bytes handled in the first loop. */
|
|
len -= (-dstp) % OPSIZ;
|
|
|
|
/* There are at least some bytes to set.
|
|
No need to test for LEN == 0 in this alignment loop. */
|
|
|
|
/* Fill bytes until DSTP is aligned on a longword boundary. */
|
|
asm volatile ("rep\n"
|
|
"stosb" /* %0, %2, %3 */ :
|
|
"=D" (dstp), "=c" (d0) :
|
|
"0" (dstp), "1" ((-dstp) % OPSIZ), "a" (x) :
|
|
"memory");
|
|
|
|
/* Fill longwords. */
|
|
asm volatile ("rep\n"
|
|
"stosl" /* %0, %2, %3 */ :
|
|
"=D" (dstp), "=c" (d0) :
|
|
"0" (dstp), "1" (len / OPSIZ), "a" (x) :
|
|
"memory");
|
|
len %= OPSIZ;
|
|
}
|
|
|
|
/* Write the last few bytes. */
|
|
asm volatile ("rep\n"
|
|
"stosb" /* %0, %2, %3 */ :
|
|
"=D" (dstp), "=c" (d0) :
|
|
"0" (dstp), "c" (len), "a" (x) :
|
|
"memory");
|
|
}
|
|
weak_alias (__bzero, bzero)
|
|
|
|
#else
|
|
#include <string/bzero.c>
|
|
#endif
|