96 lines
2.3 KiB
C
96 lines
2.3 KiB
C
|
/*
|
||
|
|
* Copyright (C) 1991,1992,1993,1997,1998,2003, 2005 Free Software Foundation, Inc.
|
||
|
|
* This file is part of the GNU C Library.
|
||
|
|
* Copyright (c) 2011 The Chromium OS Authors.
|
||
|
|
*
|
||
|
|
* This program is free software; you can redistribute it and/or
|
||
|
|
* modify it under the terms of the GNU General Public License as
|
||
|
|
* published by the Free Software Foundation; either version 2 of
|
||
|
|
* the License, or (at your option) any later version.
|
||
|
|
*
|
||
|
|
* This program 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 General Public License for more details.
|
||
|
|
*/
|
||
|
|
|
||
|
|
/* From glibc-2.14, sysdeps/i386/memset.c */
|
||
|
|
|
||
|
|
#include <stdint.h>
|
||
|
|
|
||
|
|
#include "string.h"
|
||
|
|
|
||
|
|
typedef uint32_t op_t;
|
||
|
|
|
||
|
|
void *memset(void *dstpp, int c, size_t len)
|
||
|
|
{
|
||
|
|
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 = (unsigned char) c;
|
||
|
|
|
||
|
|
/* Clear the direction flag, so filling will move forward. */
|
||
|
|
asm volatile("cld");
|
||
|
|
|
||
|
|
/* This threshold value is optimal. */
|
||
|
|
if (len >= 12) {
|
||
|
|
/* Fill X with four copies of the char we want to fill with. */
|
||
|
|
x |= (x << 8);
|
||
|
|
x |= (x << 16);
|
||
|
|
|
||
|
|
/* Adjust LEN for the bytes handled in the first loop. */
|
||
|
|
len -= (-dstp) % sizeof(op_t);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* 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) % sizeof(op_t)), "a" (x) :
|
||
|
|
"memory");
|
||
|
|
|
||
|
|
/* Fill longwords. */
|
||
|
|
asm volatile(
|
||
|
|
"rep\n"
|
||
|
|
"stosl" /* %0, %2, %3 */ :
|
||
|
|
"=D" (dstp), "=c" (d0) :
|
||
|
|
"0" (dstp), "1" (len / sizeof(op_t)), "a" (x) :
|
||
|
|
"memory");
|
||
|
|
len %= sizeof(op_t);
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Write the last few bytes. */
|
||
|
|
asm volatile(
|
||
|
|
"rep\n"
|
||
|
|
"stosb" /* %0, %2, %3 */ :
|
||
|
|
"=D" (dstp), "=c" (d0) :
|
||
|
|
"0" (dstp), "1" (len), "a" (x) :
|
||
|
|
"memory");
|
||
|
|
|
||
|
|
return dstpp;
|
||
|
|
}
|
||
|
|
|
||
|
|
void *memcpy(void *dest, const void *src, size_t n)
|
||
|
|
{
|
||
|
|
unsigned long d0, d1, d2;
|
||
|
|
|
||
|
|
asm volatile(
|
||
|
|
"rep ; movsl\n\t"
|
||
|
|
"movl %4,%%ecx\n\t"
|
||
|
|
"rep ; movsb\n\t"
|
||
|
|
: "=&c" (d0), "=&D" (d1), "=&S" (d2)
|
||
|
|
: "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
|
||
|
|
: "memory"
|
||
|
|
);
|
||
|
|
|
||
|
|
return dest;
|
||
|
|
}
|