contrib/nvi/clib/memmove.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Chris Torek.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #include "config.h"
  38
  39 #if defined(LIBC_SCCS) && !defined(lint)
  40 static const char sccsid[] = "@(#)bcopy.c       8.1 (Berkeley) 6/4/93";
  41 #endif /* LIBC_SCCS and not lint */
  42
  43 #include <string.h>
  44
  45 /*
  46  * sizeof(word) MUST BE A POWER OF TWO
  47  * SO THAT wmask BELOW IS ALL ONES
  48  */
  49 typedef int word;               /* "word" used for optimal copy speed */
  50
  51 #define wsize   sizeof(word)
  52 #define wmask   (wsize - 1)
  53
  54 /*
  55  * Copy a block of memory, handling overlap.
  56  * This is the routine that actually implements
  57  * (the portable versions of) bcopy, memcpy, and memmove.
  58  *
  59  * PUBLIC: #ifndef HAVE_MEMCPY
  60  * PUBLIC: void *memcpy __P((void *, const void *, size_t));
  61  * PUBLIC: #endif
  62  * PUBLIC: #ifndef HAVE_MEMMOVE
  63  * PUBLIC: void *memmove __P((void *, const void *, size_t));
  64  * PUBLIC: #endif
  65  */
  66 #ifdef MEMCOPY
  67 void *
  68 memcpy(dst0, src0, length)
  69 #else
  70 #ifdef MEMMOVE
  71 void *
  72 memmove(dst0, src0, length)
  73 #else
  74 void
  75 bcopy(src0, dst0, length)
  76 #endif
  77 #endif
  78         void *dst0;
  79         const void *src0;
  80         register size_t length;
  81 {
  82         register char *dst = dst0;
  83         register const char *src = src0;
  84         register size_t t;
  85
  86         if (length == 0 || dst == src)          /* nothing to do */
  87                 goto done;
  88
  89         /*
  90          * Macros: loop-t-times; and loop-t-times, t>0
  91          */
  92 #define TLOOP(s) if (t) TLOOP1(s)
  93 #define TLOOP1(s) do { s; } while (--t)
  94
  95         if ((unsigned long)dst < (unsigned long)src) {
  96                 /*
  97                  * Copy forward.
  98                  */
  99                 t = (int)src;   /* only need low bits */
 100                 if ((t | (int)dst) & wmask) {
 101                         /*
 102                          * Try to align operands.  This cannot be done
 103                          * unless the low bits match.
 104                          */
 105                         if ((t ^ (int)dst) & wmask || length < wsize)
 106                                 t = length;
 107                         else
 108                                 t = wsize - (t & wmask);
 109                         length -= t;
 110                         TLOOP1(*dst++ = *src++);
 111                 }
 112                 /*
 113                  * Copy whole words, then mop up any trailing bytes.
 114                  */
 115                 t = length / wsize;
 116                 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
 117                 t = length & wmask;
 118                 TLOOP(*dst++ = *src++);
 119         } else {
 120                 /*
 121                  * Copy backwards.  Otherwise essentially the same.
 122                  * Alignment works as before, except that it takes
 123                  * (t&wmask) bytes to align, not wsize-(t&wmask).
 124                  */
 125                 src += length;
 126                 dst += length;
 127                 t = (int)src;
 128                 if ((t | (int)dst) & wmask) {
 129                         if ((t ^ (int)dst) & wmask || length <= wsize)
 130                                 t = length;
 131                         else
 132                                 t &= wmask;
 133                         length -= t;
 134                         TLOOP1(*--dst = *--src);
 135                 }
 136                 t = length / wsize;
 137                 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
 138                 t = length & wmask;
 139                 TLOOP(*--dst = *--src);
 140         }
 141 done:
 142 #if defined(MEMCOPY) || defined(MEMMOVE)
 143         return (dst0);
 144 #else
 145         return;
 146 #endif
 147 }