2 * Copyright (C) 1991,1992,1993,1997,1998,2003, 2005 Free Software Foundation, Inc.
3 * This file is part of the GNU C Library.
4 * Copyright (c) 2011 The Chromium OS Authors.
6 * See file CREDITS for list of people who contributed to this
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License as
11 * published by the Free Software Foundation; either version 2 of
12 * the License, or (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
25 /* From glibc-2.14, sysdeps/i386/memset.c */
28 #include <asm/string.h>
29 #include <linux/types.h>
31 typedef uint32_t op_t;
33 void *memset(void *dstpp, int c, size_t len)
36 unsigned long int dstp = (unsigned long int) dstpp;
38 /* This explicit register allocation improves code very much indeed. */
39 register op_t x asm("ax");
41 x = (unsigned char) c;
43 /* Clear the direction flag, so filling will move forward. */
46 /* This threshold value is optimal. */
48 /* Fill X with four copies of the char we want to fill with. */
52 /* Adjust LEN for the bytes handled in the first loop. */
53 len -= (-dstp) % sizeof(op_t);
56 * There are at least some bytes to set. No need to test for
57 * LEN == 0 in this alignment loop.
60 /* Fill bytes until DSTP is aligned on a longword boundary. */
63 "stosb" /* %0, %2, %3 */ :
64 "=D" (dstp), "=c" (d0) :
65 "0" (dstp), "1" ((-dstp) % sizeof(op_t)), "a" (x) :
71 "stosl" /* %0, %2, %3 */ :
72 "=D" (dstp), "=c" (d0) :
73 "0" (dstp), "1" (len / sizeof(op_t)), "a" (x) :
78 /* Write the last few bytes. */
81 "stosb" /* %0, %2, %3 */ :
82 "=D" (dstp), "=c" (d0) :
83 "0" (dstp), "1" (len), "a" (x) :