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 #if defined(LIBC_SCCS) && !defined(lint) 38 static char sccsid[] = "@(#)memset.c 8.1 (Berkeley) 6/4/93"; 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include <sys/types.h> 42 43 #include <limits.h> 44 #include <string.h> 45 46 #define wsize sizeof(u_int) 47 #define wmask (wsize - 1) 48 49 #ifdef BZERO 50 #define RETURN return 51 #define VAL 0 52 #define WIDEVAL 0 53 54 void 55 bzero(dst0, length) 56 void *dst0; 57 register size_t length; 58 #else 59 #define RETURN return (dst0) 60 #define VAL c0 61 #define WIDEVAL c 62 63 void * 64 memset(dst0, c0, length) 65 void *dst0; 66 register int c0; 67 register size_t length; 68 #endif 69 { 70 register size_t t; 71 register u_int c; 72 register u_char *dst; 73 74 dst = dst0; 75 /* 76 * If not enough words, just fill bytes. A length >= 2 words 77 * guarantees that at least one of them is `complete' after 78 * any necessary alignment. For instance: 79 * 80 * |-----------|-----------|-----------| 81 * |00|01|02|03|04|05|06|07|08|09|0A|00| 82 * ^---------------------^ 83 * dst dst+length-1 84 * 85 * but we use a minimum of 3 here since the overhead of the code 86 * to do word writes is substantial. 87 */ 88 if (length < 3 * wsize) { 89 while (length != 0) { 90 *dst++ = VAL; 91 --length; 92 } 93 RETURN; 94 } 95 96 #ifndef BZERO 97 if ((c = (u_char)c0) != 0) { /* Fill the word. */ 98 c = (c << 8) | c; /* u_int is 16 bits. */ 99 #if UINT_MAX > 0xffff 100 c = (c << 16) | c; /* u_int is 32 bits. */ 101 #endif 102 #if UINT_MAX > 0xffffffff 103 c = (c << 32) | c; /* u_int is 64 bits. */ 104 #endif 105 } 106 #endif 107 /* Align destination by filling in bytes. */ 108 if ((t = (int)dst & wmask) != 0) { 109 t = wsize - t; 110 length -= t; 111 do { 112 *dst++ = VAL; 113 } while (--t != 0); 114 } 115 116 /* Fill words. Length was >= 2*words so we know t >= 1 here. */ 117 t = length / wsize; 118 do { 119 *(u_int *)dst = WIDEVAL; 120 dst += wsize; 121 } while (--t != 0); 122 123 /* Mop up trailing bytes, if any. */ 124 t = length & wmask; 125 if (t != 0) 126 do { 127 *dst++ = VAL; 128 } while (--t != 0); 129 RETURN; 130 } 131