string/memset.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * Copyright (c) 1990, 1993
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * This code is derived from software contributed to Berkeley by
  30  * Mike Hibler and Chris Torek.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  * 3. All advertising materials mentioning features or use of this software
  41  *    must display the following acknowledgement:
  42  *      This product includes software developed by the University of
  43  *      California, Berkeley and its contributors.
  44  * 4. Neither the name of the University nor the names of its contributors
  45  *    may be used to endorse or promote products derived from this software
  46  *    without specific prior written permission.
  47  *
  48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  58  * SUCH DAMAGE.
  59  */
  60
  61 #if defined(LIBC_SCCS) && !defined(lint)
  62 static char sccsid[] = "@(#)memset.c    8.1 (Berkeley) 6/4/93";
  63 #endif /* LIBC_SCCS and not lint */
  64
  65 #include <sys/types.h>
  66
  67 #include <limits.h>
  68 #include <string.h>
  69
  70 #define wsize   sizeof(u_int)
  71 #define wmask   (wsize - 1)
  72
  73 #ifndef __ppc__
  74
  75 #ifdef BZERO
  76 #define RETURN  return
  77 #define VAL     0
  78 #define WIDEVAL 0
  79
  80 void
  81 bzero(dst0, length)
  82         void *dst0;
  83         register size_t length;
  84 #else
  85 #define RETURN  return (dst0)
  86 #define VAL     c0
  87 #define WIDEVAL c
  88
  89 void *
  90 memset(dst0, c0, length)
  91         void *dst0;
  92         register int c0;
  93         register size_t length;
  94 #endif
  95 {
  96         register size_t t;
  97         register u_int c;
  98         register u_char *dst;
  99
 100         dst = dst0;
 101         /*
 102          * If not enough words, just fill bytes.  A length >= 2 words
 103          * guarantees that at least one of them is `complete' after
 104          * any necessary alignment.  For instance:
 105          *
 106          *      |-----------|-----------|-----------|
 107          *      |00|01|02|03|04|05|06|07|08|09|0A|00|
 108          *                ^---------------------^
 109          *               dst             dst+length-1
 110          *
 111          * but we use a minimum of 3 here since the overhead of the code
 112          * to do word writes is substantial.
 113          */
 114         if (length < 3 * wsize) {
 115                 while (length != 0) {
 116                         *dst++ = VAL;
 117                         --length;
 118                 }
 119                 RETURN;
 120         }
 121
 122 #ifndef BZERO
 123         if ((c = (u_char)c0) != 0) {    /* Fill the word. */
 124                 c = (c << 8) | c;       /* u_int is 16 bits. */
 125 #if UINT_MAX > 0xffff
 126                 c = (c << 16) | c;      /* u_int is 32 bits. */
 127 #endif
 128 #if UINT_MAX > 0xffffffff
 129                 c = (c << 32) | c;      /* u_int is 64 bits. */
 130 #endif
 131         }
 132 #endif
 133         /* Align destination by filling in bytes. */
 134         if ((t = (int)dst & wmask) != 0) {
 135                 t = wsize - t;
 136                 length -= t;
 137                 do {
 138                         *dst++ = VAL;
 139                 } while (--t != 0);
 140         }
 141
 142         /* Fill words.  Length was >= 2*words so we know t >= 1 here. */
 143         t = length / wsize;
 144         do {
 145                 *(u_int *)dst = WIDEVAL;
 146                 dst += wsize;
 147         } while (--t != 0);
 148
 149         /* Mop up trailing bytes, if any. */
 150         t = length & wmask;
 151         if (t != 0)
 152                 do {
 153                         *dst++ = VAL;
 154                 } while (--t != 0);
 155         RETURN;
 156 }
 157 #endif /* __ppc__ */