diff options
Diffstat (limited to 'lib/libc/string/memset.c')
| -rw-r--r-- | lib/libc/string/memset.c | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/lib/libc/string/memset.c b/lib/libc/string/memset.c new file mode 100644 index 0000000..ad0d513 --- /dev/null +++ b/lib/libc/string/memset.c @@ -0,0 +1,128 @@ +/*- + * Copyright (c) 1990, 1993 + * The Regents of the University of California. All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Mike Hibler and Chris Torek. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#if defined(LIBC_SCCS) && !defined(lint) +static char sccsid[] = "@(#)memset.c 8.1 (Berkeley) 6/4/93"; +#endif /* LIBC_SCCS and not lint */ +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <sys/types.h> + +#include <limits.h> + +#define wsize sizeof(u_int) +#define wmask (wsize - 1) + +#ifdef BZERO +#include <strings.h> + +#define RETURN return +#define VAL 0 +#define WIDEVAL 0 + +void +bzero(void *dst0, size_t length) +#else +#include <string.h> + +#define RETURN return (dst0) +#define VAL c0 +#define WIDEVAL c + +void * +memset(void *dst0, int c0, size_t length) +#endif +{ + size_t t; +#ifndef BZERO + u_int c; +#endif + u_char *dst; + + dst = dst0; + /* + * If not enough words, just fill bytes. A length >= 2 words + * guarantees that at least one of them is `complete' after + * any necessary alignment. For instance: + * + * |-----------|-----------|-----------| + * |00|01|02|03|04|05|06|07|08|09|0A|00| + * ^---------------------^ + * dst dst+length-1 + * + * but we use a minimum of 3 here since the overhead of the code + * to do word writes is substantial. + */ + if (length < 3 * wsize) { + while (length != 0) { + *dst++ = VAL; + --length; + } + RETURN; + } + +#ifndef BZERO + if ((c = (u_char)c0) != 0) { /* Fill the word. */ + c = (c << 8) | c; /* u_int is 16 bits. */ +#if UINT_MAX > 0xffff + c = (c << 16) | c; /* u_int is 32 bits. */ +#endif +#if UINT_MAX > 0xffffffff + c = (c << 32) | c; /* u_int is 64 bits. */ +#endif + } +#endif + /* Align destination by filling in bytes. */ + if ((t = (long)dst & wmask) != 0) { + t = wsize - t; + length -= t; + do { + *dst++ = VAL; + } while (--t != 0); + } + + /* Fill words. Length was >= 2*words so we know t >= 1 here. */ + t = length / wsize; + do { + *(u_int *)dst = WIDEVAL; + dst += wsize; + } while (--t != 0); + + /* Mop up trailing bytes, if any. */ + t = length & wmask; + if (t != 0) + do { + *dst++ = VAL; + } while (--t != 0); + RETURN; +} |
