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) :
90 #define OPSIZ (sizeof(op_t))
92 #define BYTE_COPY_FWD(dst_bp, src_bp, nbytes) \
96 /* Clear the direction flag, so copying goes forward. */ \
101 "=D" (dst_bp), "=S" (src_bp), "=c" (__d0) : \
102 "0" (dst_bp), "1" (src_bp), "2" (nbytes) : \
106 #define WORD_COPY_FWD(dst_bp, src_bp, nbytes_left, nbytes) \
110 /* Clear the direction flag, so copying goes forward. */ \
112 /* Copy longwords. */ \
115 "=D" (dst_bp), "=S" (src_bp), "=c" (__d0) : \
116 "0" (dst_bp), "1" (src_bp), "2" ((nbytes) / 4) : \
118 (nbytes_left) = (nbytes) % 4; \
121 void *memcpy(void *dstpp, const void *srcpp, size_t len)
123 unsigned long int dstp = (long int)dstpp;
124 unsigned long int srcp = (long int)srcpp;
126 /* Copy from the beginning to the end. */
128 /* If there not too few bytes to copy, use word copy. */
129 if (len >= OP_T_THRES) {
130 /* Copy just a few bytes to make DSTP aligned. */
131 len -= (-dstp) % OPSIZ;
132 BYTE_COPY_FWD(dstp, srcp, (-dstp) % OPSIZ);
134 /* Copy from SRCP to DSTP taking advantage of the known
135 * alignment of DSTP. Number of bytes remaining is put
136 * in the third argument, i.e. in LEN. This number may
137 * vary from machine to machine.
139 WORD_COPY_FWD(dstp, srcp, len, len);
141 /* Fall out and copy the tail. */
144 /* There are just a few bytes to copy. Use byte memory operations. */
145 BYTE_COPY_FWD(dstp, srcp, len);