compiler/clib/bcopy.c

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