1 /*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Mike Hibler and Chris Torek. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #include "config.h" 38 39 #if defined(LIBC_SCCS) && !defined(lint) 40 static const char sccsid[] = "@(#)memset.c 8.1 (Berkeley) 6/4/93"; 41 #endif /* LIBC_SCCS and not lint */ 42 43 #include <sys/types.h> 44 45 #include <limits.h> 46 #include <string.h> 47 48 /* 49 * PUBLIC: #ifndef HAVE_MEMSET 50 * PUBLIC: void *memset __P((void *, int, size_t)); 51 * PUBLIC: #endif 52 */ 53 #define wsize sizeof(u_int) 54 #define wmask (wsize - 1) 55 56 #ifdef BZERO 57 #define RETURN return 58 #define VAL 0 59 #define WIDEVAL 0 60 61 void 62 bzero(dst0, length) 63 void *dst0; 64 register size_t length; 65 #else 66 #define RETURN return (dst0) 67 #define VAL c0 68 #define WIDEVAL c 69 70 void * 71 memset(void *dst0, register int c0, register size_t length) 72 73 74 75 #endif 76 { 77 register size_t t; 78 register u_int c; 79 register u_char *dst; 80 81 dst = dst0; 82 /* 83 * If not enough words, just fill bytes. A length >= 2 words 84 * guarantees that at least one of them is `complete' after 85 * any necessary alignment. For instance: 86 * 87 * |-----------|-----------|-----------| 88 * |00|01|02|03|04|05|06|07|08|09|0A|00| 89 * ^---------------------^ 90 * dst dst+length-1 91 * 92 * but we use a minimum of 3 here since the overhead of the code 93 * to do word writes is substantial. 94 */ 95 if (length < 3 * wsize) { 96 while (length != 0) { 97 *dst++ = VAL; 98 --length; 99 } 100 RETURN; 101 } 102 103 #ifndef BZERO 104 if ((c = (u_char)c0) != 0) { /* Fill the word. */ 105 c = (c << 8) | c; /* u_int is 16 bits. */ 106 #if UINT_MAX > 0xffff 107 c = (c << 16) | c; /* u_int is 32 bits. */ 108 #endif 109 #if UINT_MAX > 0xffffffff 110 c = (c << 32) | c; /* u_int is 64 bits. */ 111 #endif 112 } 113 #endif 114 /* Align destination by filling in bytes. */ 115 if ((t = (int)dst & wmask) != 0) { 116 t = wsize - t; 117 length -= t; 118 do { 119 *dst++ = VAL; 120 } while (--t != 0); 121 } 122 123 /* Fill words. Length was >= 2*words so we know t >= 1 here. */ 124 t = length / wsize; 125 do { 126 *(u_int *)dst = WIDEVAL; 127 dst += wsize; 128 } while (--t != 0); 129 130 /* Mop up trailing bytes, if any. */ 131 t = length & wmask; 132 if (t != 0) 133 do { 134 *dst++ = VAL; 135 } while (--t != 0); 136 RETURN; 137 } 138