common/lib/libc/string/memset.c

   1 /*      $NetBSD: memset.c,v 1.8 2009/03/18 12:25:06 tsutsui Exp $       */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Mike Hibler and Chris Torek.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/cdefs.h>
  36 #if defined(LIBC_SCCS) && !defined(lint)
  37 #if 0
  38 static char sccsid[] = "@(#)memset.c    8.1 (Berkeley) 6/4/93";
  39 #else
  40 __RCSID("$NetBSD: memset.c,v 1.8 2009/03/18 12:25:06 tsutsui Exp $");
  41 #endif
  42 #endif /* LIBC_SCCS and not lint */
  43
  44 #include <sys/types.h>
  45
  46 #if !defined(_KERNEL) && !defined(_STANDALONE)
  47 #include <assert.h>
  48 #include <limits.h>
  49 #include <string.h>
  50 #else
  51 #include <lib/libkern/libkern.h>
  52 #if defined(BZERO) && defined(_STANDALONE)
  53 #include <lib/libsa/stand.h>
  54 #endif
  55 #include <machine/limits.h>
  56 #endif
  57
  58 #define wsize   sizeof(u_int)
  59 #define wmask   (wsize - 1)
  60
  61 #ifdef _FORTIFY_SOURCE
  62 #undef bzero
  63 #undef memset
  64 #endif
  65
  66 #ifndef __OPTIMIZE_SIZE__
  67 #ifdef BZERO
  68 #define RETURN  return
  69 #define VAL     0
  70 #define WIDEVAL 0
  71
  72 void
  73 bzero(void *dst0, size_t length)
  74 #else
  75 #define RETURN  return (dst0)
  76 #define VAL     c0
  77 #define WIDEVAL c
  78
  79 void *
  80 memset(void *dst0, int c0, size_t length)
  81 #endif
  82 {
  83         size_t t;
  84 #ifndef BZERO
  85         u_int c;
  86 #endif
  87         u_char *dst;
  88
  89         _DIAGASSERT(dst0 != 0);
  90
  91         dst = dst0;
  92         /*
  93          * If not enough words, just fill bytes.  A length >= 2 words
  94          * guarantees that at least one of them is `complete' after
  95          * any necessary alignment.  For instance:
  96          *
  97          *      |-----------|-----------|-----------|
  98          *      |00|01|02|03|04|05|06|07|08|09|0A|00|
  99          *                ^---------------------^
 100          *               dst             dst+length-1
 101          *
 102          * but we use a minimum of 3 here since the overhead of the code
 103          * to do word writes is substantial.
 104          */
 105         if (length < 3 * wsize) {
 106                 while (length != 0) {
 107                         *dst++ = VAL;
 108                         --length;
 109                 }
 110                 RETURN;
 111         }
 112
 113 #ifndef BZERO
 114         if ((c = (u_char)c0) != 0) {    /* Fill the word. */
 115                 c = (c << 8) | c;       /* u_int is 16 bits. */
 116 #if UINT_MAX > 0xffff
 117                 c = (c << 16) | c;      /* u_int is 32 bits. */
 118 #endif
 119 #if UINT_MAX > 0xffffffff
 120                 c = (c << 32) | c;      /* u_int is 64 bits. */
 121 #endif
 122         }
 123 #endif
 124         /* Align destination by filling in bytes. */
 125         if ((t = (size_t)((u_long)dst & wmask)) != 0) {
 126                 t = wsize - t;
 127                 length -= t;
 128                 do {
 129                         *dst++ = VAL;
 130                 } while (--t != 0);
 131         }
 132
 133         /* Fill words.  Length was >= 2*words so we know t >= 1 here. */
 134         t = length / wsize;
 135         do {
 136                 *(u_int *)(void *)dst = WIDEVAL;
 137                 dst += wsize;
 138         } while (--t != 0);
 139
 140         /* Mop up trailing bytes, if any. */
 141         t = length & wmask;
 142         if (t != 0)
 143                 do {
 144                         *dst++ = VAL;
 145                 } while (--t != 0);
 146         RETURN;
 147 }
 148 #else /* __OPTIMIZE_SIZE__ */
 149 #ifdef BZERO
 150 void
 151 bzero(void *dstv, size_t length)
 152 {
 153         u_char *dst = dstv;
 154         while (length-- > 0)
 155                 *dst++ = 0;
 156 }
 157 #else
 158 void *
 159 memset(void *dstv, int c, size_t length)
 160 {
 161         u_char *dst = dstv;
 162         while (length-- > 0)
 163                 *dst++ = c;
 164         return dstv;
 165 }
 166 #endif /* BZERO */
 167 #endif /* __OPTIMIZE_SIZE__ */