string.subproj/memset.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1990, 1993
  24  *      The Regents of the University of California.  All rights reserved.
  25  *
  26  * This code is derived from software contributed to Berkeley by
  27  * Mike Hibler and Chris Torek.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by the University of
  40  *      California, Berkeley and its contributors.
  41  * 4. Neither the name of the University nor the names of its contributors
  42  *    may be used to endorse or promote products derived from this software
  43  *    without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  */
  57
  58 #if defined(LIBC_SCCS) && !defined(lint)
  59 static char sccsid[] = "@(#)memset.c    8.1 (Berkeley) 6/4/93";
  60 #endif /* LIBC_SCCS and not lint */
  61
  62 #include <sys/types.h>
  63
  64 #include <limits.h>
  65 #include <string.h>
  66
  67 #define wsize   sizeof(u_int)
  68 #define wmask   (wsize - 1)
  69
  70 #ifdef BZERO
  71 #define RETURN  return
  72 #define VAL     0
  73 #define WIDEVAL 0
  74
  75 void
  76 bzero(dst0, length)
  77         void *dst0;
  78         register size_t length;
  79 #else
  80 #define RETURN  return (dst0)
  81 #define VAL     c0
  82 #define WIDEVAL c
  83
  84 void *
  85 memset(dst0, c0, length)
  86         void *dst0;
  87         register int c0;
  88         register size_t length;
  89 #endif
  90 {
  91         register size_t t;
  92         register u_int c;
  93         register u_char *dst;
  94
  95         dst = dst0;
  96         /*
  97          * If not enough words, just fill bytes.  A length >= 2 words
  98          * guarantees that at least one of them is `complete' after
  99          * any necessary alignment.  For instance:
 100          *
 101          *      |-----------|-----------|-----------|
 102          *      |00|01|02|03|04|05|06|07|08|09|0A|00|
 103          *                ^---------------------^
 104          *               dst             dst+length-1
 105          *
 106          * but we use a minimum of 3 here since the overhead of the code
 107          * to do word writes is substantial.
 108          */
 109         if (length < 3 * wsize) {
 110                 while (length != 0) {
 111                         *dst++ = VAL;
 112                         --length;
 113                 }
 114                 RETURN;
 115         }
 116
 117 #ifndef BZERO
 118         if ((c = (u_char)c0) != 0) {    /* Fill the word. */
 119                 c = (c << 8) | c;       /* u_int is 16 bits. */
 120 #if UINT_MAX > 0xffff
 121                 c = (c << 16) | c;      /* u_int is 32 bits. */
 122 #endif
 123 #if UINT_MAX > 0xffffffff
 124                 c = (c << 32) | c;      /* u_int is 64 bits. */
 125 #endif
 126         }
 127 #endif
 128         /* Align destination by filling in bytes. */
 129         if ((t = (int)dst & wmask) != 0) {
 130                 t = wsize - t;
 131                 length -= t;
 132                 do {
 133                         *dst++ = VAL;
 134                 } while (--t != 0);
 135         }
 136
 137         /* Fill words.  Length was >= 2*words so we know t >= 1 here. */
 138         t = length / wsize;
 139         do {
 140                 *(u_int *)dst = WIDEVAL;
 141                 dst += wsize;
 142         } while (--t != 0);
 143
 144         /* Mop up trailing bytes, if any. */
 145         t = length & wmask;
 146         if (t != 0)
 147                 do {
 148                         *dst++ = VAL;
 149                 } while (--t != 0);
 150         RETURN;
 151 }