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root/usr/lib/libc/string/bcopy.c

DEFINITIONS

1. memcpy

   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. Neither the name of the University nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  33 #include <sys/cdefs.h>
  34 #include <string.h>
  36 /*
  37  * Copy a block of memory, handling overlap.
  38  * This is the routine that actually implements
  39  * (the portable versions of) bcopy, memcpy, and memmove.
  40  */
  41 #ifdef MEMCOPY
  42 void *
memcpy(dst0, src0, length)
  44 #else
  45 #ifdef MEMMOVE
  46 void *
memmove(dst0, src0, length)
  48 #else
  49 void
bcopy(src0, dst0, length)
  51 #endif
  52 #endif
  53         void *dst0;
  54         const void *src0;
size_t length;
  56 {
  57         char *dst = dst0;
  58         const char *src = src0;
  60         if (length == 0 || dst == src)          /* nothing to do */
  61                 goto done;
  63         if (((unsigned long)dst < (unsigned long)src) &&
  64             ((unsigned long)dst < (unsigned long)src + length)) {
  65                 /* Copy backwards. */
src += length;
dst += length;
  68                 while (length--) {
  69                         *--dst = *--src;
  70                 }
  71         } else {
  72                 while (length--) {
  73                         *dst++ = *src++;
  74                 }
  75         }
done:
  77 #if defined(MEMCOPY) || defined(MEMMOVE)
  78         return (dst0);
  79 #else
  80         return;
  81 #endif
  82 }