The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/powerpc/powerpc/bcopy.c

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    1 /*-
    2  * Copyright (c) 1990 The Regents of the University of California.
    3  * 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  * 4. 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  */
   32 
   33 #if defined(LIBC_SCCS) && !defined(lint)
   34 #if 0
   35 static char *sccsid = "from: @(#)bcopy.c      5.11 (Berkeley) 6/21/91";
   36 #endif
   37 #if 0
   38 static char *rcsid = "$NetBSD: bcopy.c,v 1.2 1997/04/16 22:09:41 thorpej Exp $";
   39 #endif
   40 #endif /* LIBC_SCCS and not lint */
   41 #include <sys/cdefs.h>
   42 __FBSDID("$FreeBSD: releng/9.0/sys/powerpc/powerpc/bcopy.c 209850 2010-07-09 14:01:18Z nwhitehorn $");
   43 
   44 #include <sys/param.h>
   45 #ifdef _KERNEL
   46 #include <sys/systm.h>
   47 #else
   48 #include <string.h>
   49 #endif
   50 
   51 /*
   52  * sizeof(word) MUST BE A POWER OF TWO
   53  * SO THAT wmask BELOW IS ALL ONES
   54  */
   55 typedef long    word;           /* "word" used for optimal copy speed */
   56 
   57 #define wsize   sizeof(word)
   58 #define wmask   (wsize - 1)
   59 
   60 /*
   61  * Copy a block of memory, handling overlap.
   62  * This is the routine that actually implements
   63  * (the portable versions of) bcopy, memcpy, and memmove.
   64  */
   65 void *
   66 memcpy(void *dst0, const void *src0, size_t length)
   67 {
   68         char            *dst;
   69         const char      *src;
   70         size_t          t;
   71 
   72         dst = dst0;
   73         src = src0;
   74 
   75         if (length == 0 || dst == src) {        /* nothing to do */
   76                 goto done;
   77         }
   78 
   79         /*
   80          * Macros: loop-t-times; and loop-t-times, t>0
   81          */
   82 #define TLOOP(s) if (t) TLOOP1(s)
   83 #define TLOOP1(s) do { s; } while (--t)
   84 
   85         if ((unsigned long)dst < (unsigned long)src) {
   86                 /*
   87                  * Copy forward.
   88                  */
   89                 t = (size_t)src;        /* only need low bits */
   90 
   91                 if ((t | (uintptr_t)dst) & wmask) {
   92                         /*
   93                          * Try to align operands.  This cannot be done
   94                          * unless the low bits match.
   95                          */
   96                         if ((t ^ (uintptr_t)dst) & wmask || length < wsize) {
   97                                 t = length;
   98                         } else {
   99                                 t = wsize - (t & wmask);
  100                         }
  101 
  102                         length -= t;
  103                         TLOOP1(*dst++ = *src++);
  104                 }
  105                 /*
  106                  * Copy whole words, then mop up any trailing bytes.
  107                  */
  108                 t = length / wsize;
  109                 TLOOP(*(word *)dst = *(const word *)src; src += wsize;
  110                     dst += wsize);
  111                 t = length & wmask;
  112                 TLOOP(*dst++ = *src++);
  113         } else {
  114                 /*
  115                  * Copy backwards.  Otherwise essentially the same.
  116                  * Alignment works as before, except that it takes
  117                  * (t&wmask) bytes to align, not wsize-(t&wmask).
  118                  */
  119                 src += length;
  120                 dst += length;
  121                 t = (uintptr_t)src;
  122 
  123                 if ((t | (uintptr_t)dst) & wmask) {
  124                         if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) {
  125                                 t = length;
  126                         } else {
  127                                 t &= wmask;
  128                         }
  129 
  130                         length -= t;
  131                         TLOOP1(*--dst = *--src);
  132                 }
  133                 t = length / wsize;
  134                 TLOOP(src -= wsize; dst -= wsize;
  135                     *(word *)dst = *(const word *)src);
  136                 t = length & wmask;
  137                 TLOOP(*--dst = *--src);
  138         }
  139 done:
  140         return (dst0);
  141 }
  142 
  143 void
  144 bcopy(const void *src0, void *dst0, size_t length)
  145 {
  146 
  147         memcpy(dst0, src0, length);
  148 }
  149 

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