dist/nvi/clib/memset.c

   1 /*      $NetBSD$ */
   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. All advertising materials mentioning features or use of this software
  19  *    must display the following acknowledgement:
  20  *      This product includes software developed by the University of
  21  *      California, Berkeley and its contributors.
  22  * 4. Neither the name of the University nor the names of its contributors
  23  *    may be used to endorse or promote products derived from this software
  24  *    without specific prior written permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  36  * SUCH DAMAGE.
  37  */
  38
  39 #include "config.h"
  40
  41 #if defined(LIBC_SCCS) && !defined(lint)
  42 static const char sccsid[] = "@(#)memset.c      8.1 (Berkeley) 6/4/93";
  43 #endif /* LIBC_SCCS and not lint */
  44
  45 #include <sys/types.h>
  46
  47 #include <limits.h>
  48 #include <string.h>
  49
  50 /*
  51  * PUBLIC: #ifndef HAVE_MEMSET
  52  * PUBLIC: void *memset __P((void *, int, size_t));
  53  * PUBLIC: #endif
  54  */
  55 #define wsize   sizeof(u_int)
  56 #define wmask   (wsize - 1)
  57
  58 #ifdef BZERO
  59 #define RETURN  return
  60 #define VAL     0
  61 #define WIDEVAL 0
  62
  63 void
  64 bzero(dst0, length)
  65         void *dst0;
  66         register size_t length;
  67 #else
  68 #define RETURN  return (dst0)
  69 #define VAL     c0
  70 #define WIDEVAL c
  71
  72 void *
  73 memset(void *dst0, register int c0, register size_t length)
  74
  75
  76
  77 #endif
  78 {
  79         register size_t t;
  80         register u_int c;
  81         register u_char *dst;
  82
  83         dst = dst0;
  84         /*
  85          * If not enough words, just fill bytes.  A length >= 2 words
  86          * guarantees that at least one of them is `complete' after
  87          * any necessary alignment.  For instance:
  88          *
  89          *      |-----------|-----------|-----------|
  90          *      |00|01|02|03|04|05|06|07|08|09|0A|00|
  91          *                ^---------------------^
  92          *               dst             dst+length-1
  93          *
  94          * but we use a minimum of 3 here since the overhead of the code
  95          * to do word writes is substantial.
  96          */
  97         if (length < 3 * wsize) {
  98                 while (length != 0) {
  99                         *dst++ = VAL;
 100                         --length;
 101                 }
 102                 RETURN;
 103         }
 104
 105 #ifndef BZERO
 106         if ((c = (u_char)c0) != 0) {    /* Fill the word. */
 107                 c = (c << 8) | c;       /* u_int is 16 bits. */
 108 #if UINT_MAX > 0xffff
 109                 c = (c << 16) | c;      /* u_int is 32 bits. */
 110 #endif
 111 #if UINT_MAX > 0xffffffff
 112                 c = (c << 32) | c;      /* u_int is 64 bits. */
 113 #endif
 114         }
 115 #endif
 116         /* Align destination by filling in bytes. */
 117         if ((t = (int)dst & wmask) != 0) {
 118                 t = wsize - t;
 119                 length -= t;
 120                 do {
 121                         *dst++ = VAL;
 122                 } while (--t != 0);
 123         }
 124
 125         /* Fill words.  Length was >= 2*words so we know t >= 1 here. */
 126         t = length / wsize;
 127         do {
 128                 *(u_int *)dst = WIDEVAL;
 129                 dst += wsize;
 130         } while (--t != 0);
 131
 132         /* Mop up trailing bytes, if any. */
 133         t = length & wmask;
 134         if (t != 0)
 135                 do {
 136                         *dst++ = VAL;
 137                 } while (--t != 0);
 138         RETURN;
 139 }