common/lib/libc/string/bcopy.c

   1 /*      $NetBSD: bcopy.c,v 1.11 2014/04/16 20:39:55 joerg 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  * 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[] = "@(#)bcopy.c     8.1 (Berkeley) 6/4/93";
  39 #else
  40 __RCSID("$NetBSD: bcopy.c,v 1.11 2014/04/16 20:39:55 joerg Exp $");
  41 #endif
  42 #endif /* LIBC_SCCS and not lint */
  43
  44 #if !defined(_KERNEL) && !defined(_STANDALONE)
  45 #include <assert.h>
  46 #include <string.h>
  47 #else
  48 #include <lib/libkern/libkern.h>
  49 #if !defined(MEMCOPY) && defined(_STANDALONE)
  50 #include <lib/libsa/stand.h>
  51 #endif
  52 #endif
  53
  54 #if defined(_FORTIFY_SOURCE) || defined(_STANDALONE) || defined(_KERNEL)
  55 #undef bcopy
  56 #undef memcpy
  57 #undef memmove
  58 #endif
  59
  60 #ifndef __OPTIMIZE_SIZE__
  61 /*
  62  * sizeof(word) MUST BE A POWER OF TWO
  63  * SO THAT wmask BELOW IS ALL ONES
  64  */
  65 typedef long word;              /* "word" used for optimal copy speed */
  66
  67 #define wsize   sizeof(word)
  68 #define wmask   (wsize - 1)
  69
  70 /*
  71  * Copy a block of memory, handling overlap.
  72  * This is the routine that actually implements
  73  * (the portable versions of) bcopy, memcpy, and memmove.
  74  */
  75 #if defined(MEMCOPY)
  76 void *
  77 memcpy(void *dst0, const void *src0, size_t length)
  78 #elif defined(MEMMOVE)
  79 void *
  80 memmove(void *dst0, const void *src0, size_t length)
  81 #else
  82 void
  83 bcopy(const void *src0, void *dst0, size_t length)
  84 #endif
  85 {
  86         char *dst = dst0;
  87         const char *src = src0;
  88         size_t t;
  89         unsigned long u;
  90
  91 #if !defined(_KERNEL)
  92         _DIAGASSERT((dst0 && src0) || length == 0);
  93 #endif
  94
  95         if (length == 0 || dst == src)          /* nothing to do */
  96                 goto done;
  97
  98         /*
  99          * Macros: loop-t-times; and loop-t-times, t>0
 100          */
 101 #define TLOOP(s) if (t) TLOOP1(s)
 102 #define TLOOP1(s) do { s; } while (--t)
 103
 104         if ((unsigned long)dst < (unsigned long)src) {
 105                 /*
 106                  * Copy forward.
 107                  */
 108                 u = (unsigned long)src; /* only need low bits */
 109                 if ((u | (unsigned long)dst) & wmask) {
 110                         /*
 111                          * Try to align operands.  This cannot be done
 112                          * unless the low bits match.
 113                          */
 114                         if ((u ^ (unsigned long)dst) & wmask || length < wsize)
 115                                 t = length;
 116                         else
 117                                 t = wsize - (size_t)(u & wmask);
 118                         length -= t;
 119                         TLOOP1(*dst++ = *src++);
 120                 }
 121                 /*
 122                  * Copy whole words, then mop up any trailing bytes.
 123                  */
 124                 t = length / wsize;
 125                 TLOOP(*(word *)(void *)dst = *(const word *)(const void *)src; src += wsize; dst += wsize);
 126                 t = length & wmask;
 127                 TLOOP(*dst++ = *src++);
 128         } else {
 129                 /*
 130                  * Copy backwards.  Otherwise essentially the same.
 131                  * Alignment works as before, except that it takes
 132                  * (t&wmask) bytes to align, not wsize-(t&wmask).
 133                  */
 134                 src += length;
 135                 dst += length;
 136                 _DIAGASSERT((unsigned long)dst >= (unsigned long)dst0);
 137                 _DIAGASSERT((unsigned long)src >= (unsigned long)src0);
 138                 u = (unsigned long)src;
 139                 if ((u | (unsigned long)dst) & wmask) {
 140                         if ((u ^ (unsigned long)dst) & wmask || length <= wsize)
 141                                 t = length;
 142                         else
 143                                 t = (size_t)(u & wmask);
 144                         length -= t;
 145                         TLOOP1(*--dst = *--src);
 146                 }
 147                 t = length / wsize;
 148                 TLOOP(src -= wsize; dst -= wsize; *(word *)(void *)dst = *(const word *)(const void *)src);
 149                 t = length & wmask;
 150                 TLOOP(*--dst = *--src);
 151         }
 152 done:
 153 #if defined(MEMCOPY) || defined(MEMMOVE)
 154         return (dst0);
 155 #else
 156         return;
 157 #endif
 158 }
 159 #else /* __OPTIMIZE_SIZE__ */
 160 #if defined(MEMCOPY)
 161 /*
 162  * This is designed to be small, not fast.
 163  */
 164 void *
 165 memcpy(void *s1, const void *s2, size_t n)
 166 {
 167         const char *f = s2;
 168         char *t = s1;
 169
 170         while (n-- > 0)
 171                 *t++ = *f++;
 172         return s1;
 173 }
 174 #elif defined(MEMMOVE)
 175 /*
 176  * This is designed to be small, not fast.
 177  */
 178 void *
 179 memmove(void *s1, const void *s2, size_t n)
 180 {
 181         const char *f = s2;
 182         char *t = s1;
 183
 184         if (f < t) {
 185                 f += n;
 186                 t += n;
 187                 while (n-- > 0)
 188                         *--t = *--f;
 189         } else {
 190                 while (n-- > 0)
 191                         *t++ = *f++;
 192         }
 193         return s1;
 194 }
 195 #else
 196 /*
 197  * This is designed to be small, not fast.
 198  */
 199 void
 200 bcopy(const void *s2, void *s1, size_t n)
 201 {
 202         const char *f = s2;
 203         char *t = s1;
 204
 205         while (n-- > 0)
 206                 *t++ = *f++;
 207 }
 208 #endif
 209 #endif /* __OPTIMIZE_SIZE__ */