compiler/stdc/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 #if defined(LIBC_SCCS) && !defined(lint)
  38 static char sccsid[] = "@(#)bcopy.c     8.1 (Berkeley) 6/4/93";
  39 #endif /* LIBC_SCCS and not lint */
  40
  41 /*
  42  * sizeof(word) MUST BE A POWER OF TWO
  43  * SO THAT wmask BELOW IS ALL ONES
  44  */
  45 typedef int word;               /* "word" used for optimal copy speed */
  46
  47 #define wsize   sizeof(word)
  48 #define wmask   (wsize - 1)
  49
  50 /*
  51  * Copy a block of memory, handling overlap.
  52  */
  53
  54 /*****************************************************************************
  55
  56     NAME */
  57 #include <string.h>
  58
  59         void *memmove (
  60
  61 /*  SYNOPSIS */
  62         void *dst0,
  63         const void *src0,
  64         size_t length)
  65
  66 /*  FUNCTION
  67         Copy a block of memory, handling overlap.
  68
  69     INPUTS
  70         dst0: destination for copy
  71         src0: source for copy
  72         length: number of bytes to copy
  73
  74     RESULT
  75         dst0
  76
  77     NOTES
  78
  79     EXAMPLE
  80
  81     BUGS
  82
  83     SEE ALSO
  84
  85     INTERNALS
  86
  87 ******************************************************************************/
  88 {
  89         char *dst = dst0;
  90         const char *src = src0;
  91         size_t t;
  92
  93         if (length == 0 || dst == src)          /* nothing to do */
  94                 goto done;
  95
  96         /*
  97          * Macros: loop-t-times; and loop-t-times, t>0
  98          */
  99 #define TLOOP(s) if (t) TLOOP1(s)
 100 #define TLOOP1(s) do { s; } while (--t)
 101
 102         if ((unsigned long)dst < (unsigned long)src) {
 103                 /*
 104                  * Copy forward.
 105                  */
 106                 t = (unsigned long)src; /* only need low bits */
 107                 if ((t | (unsigned long)dst) & wmask) {
 108                         /*
 109                          * Try to align operands.  This cannot be done
 110                          * unless the low bits match.
 111                          */
 112                         if ((t ^ (unsigned long)dst) & wmask || length < wsize)
 113                                 t = length;
 114                         else
 115                                 t = wsize - (t & wmask);
 116                         length -= t;
 117                         TLOOP1(*dst++ = *src++);
 118                 }
 119                 /*
 120                  * Copy whole words, then mop up any trailing bytes.
 121                  */
 122                 t = length / wsize;
 123                 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
 124                 t = length & wmask;
 125                 TLOOP(*dst++ = *src++);
 126         } else {
 127                 /*
 128                  * Copy backwards.  Otherwise essentially the same.
 129                  * Alignment works as before, except that it takes
 130                  * (t&wmask) bytes to align, not wsize-(t&wmask).
 131                  */
 132                 src += length;
 133                 dst += length;
 134                 t = (unsigned long)src;
 135                 if ((t | (unsigned long)dst) & wmask) {
 136                         if ((t ^ (unsigned long)dst) & wmask || length <= wsize)
 137                                 t = length;
 138                         else
 139                                 t &= wmask;
 140                         length -= t;
 141                         TLOOP1(*--dst = *--src);
 142                 }
 143                 t = length / wsize;
 144                 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
 145                 t = length & wmask;
 146                 TLOOP(*--dst = *--src);
 147         }
 148 done:
 149         return (dst0);
 150 }
 151
 152
 153 /* Provide a memcpy symbol for static link library */
 154 #include <aros/system.h>
 155 #include <string.h>
 156 AROS_MAKE_ALIAS(memmove, memcpy);