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