memcpy.c

Go to the documentation of this file.
00001 /*
00002  * Copyright (C) 2004 by egnite Software GmbH. All rights reserved.
00003  *
00004  * Redistribution and use in source and binary forms, with or without
00005  * modification, are permitted provided that the following conditions
00006  * are met:
00007  *
00008  * 1. Redistributions of source code must retain the above copyright
00009  *    notice, this list of conditions and the following disclaimer.
00010  * 2. Redistributions in binary form must reproduce the above copyright
00011  *    notice, this list of conditions and the following disclaimer in the
00012  *    documentation and/or other materials provided with the distribution.
00013  * 3. Neither the name of the copyright holders nor the names of
00014  *    contributors may be used to endorse or promote products derived
00015  *    from this software without specific prior written permission.
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY EGNITE SOFTWARE GMBH AND CONTRIBUTORS
00018  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00019  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
00020  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL EGNITE
00021  * SOFTWARE GMBH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
00022  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
00023  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
00024  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
00025  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
00026  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
00027  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00028  * SUCH DAMAGE.
00029  *
00030  * For additional information see http://www.ethernut.de/
00031  *
00032  *-
00033  * Copyright (c) 1990 The Regents of the University of California.
00034  * All rights reserved.
00035  *
00036  * This code is derived from software contributed to Berkeley by
00037  * Chris Torek.
00038  *
00039  * Redistribution and use in source and binary forms, with or without
00040  * modification, are permitted provided that the following conditions
00041  * are met:
00042  * 1. Redistributions of source code must retain the above copyright
00043  *    notice, this list of conditions and the following disclaimer.
00044  * 2. Redistributions in binary form must reproduce the above copyright
00045  *    notice, this list of conditions and the following disclaimer in the
00046  *    documentation and/or other materials provided with the distribution.
00047  * 3. Neither the name of the University nor the names of its contributors
00048  *    may be used to endorse or promote products derived from this software
00049  *    without specific prior written permission.
00050  *
00051  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
00052  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00053  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00054  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
00055  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
00056  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
00057  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
00058  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00059  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
00060  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00061  * SUCH DAMAGE.
00062  */
00063 
00064 
00065 /*
00066  * $Log$
00067  * Revision 1.3  2008/02/15 17:13:01  haraldkipp
00068  * Use configurable constant attribute.
00069  *
00070  * Revision 1.2  2005/08/02 17:46:47  haraldkipp
00071  * Major API documentation update.
00072  *
00073  * Revision 1.1  2004/09/08 10:23:43  haraldkipp
00074  * Generic C string library added
00075  *
00076  */
00077 
00078 #include <compiler.h>
00079 #include <string.h>
00080 
00085 
00100 /*
00101  * sizeof(word) MUST BE A POWER OF TWO
00102  * SO THAT wmask BELOW IS ALL ONES
00103  */
00104 typedef long word;      /* "word" used for optimal copy speed */
00105 
00106 #define wsize   sizeof(word)
00107 #define wmask   (wsize - 1)
00108 
00109 /*
00110  * Copy a block of memory, handling overlap.
00111  * This is the routine that actually implements
00112  * (the portable versions of) bcopy, memcpy, and memmove.
00113  */
00114 void *memcpy(void *dst0, CONST void *src0, size_t length)
00115 {
00116     register char *dst = dst0;
00117     register CONST char *src = src0;
00118     register size_t t;
00119 
00120     if (length == 0 || dst == src)      /* nothing to do */
00121         goto done;
00122 
00123     /*
00124      * Macros: loop-t-times; and loop-t-times, t>0
00125      */
00126 #define TLOOP(s) if (t) TLOOP1(s)
00127 #define TLOOP1(s) do { s; } while (--t)
00128 
00129     if ((unsigned long)dst < (unsigned long)src) {
00130         /*
00131          * Copy forward.
00132          */
00133         t = (long)src;  /* only need low bits */
00134         if ((t | (long)dst) & wmask) {
00135             /*
00136              * Try to align operands.  This cannot be done
00137              * unless the low bits match.
00138              */
00139             if ((t ^ (long)dst) & wmask || length < wsize)
00140                 t = length;
00141             else
00142                 t = wsize - (t & wmask);
00143             length -= t;
00144             TLOOP1(*dst++ = *src++);
00145         }
00146         /*
00147          * Copy whole words, then mop up any trailing bytes.
00148          */
00149         t = length / wsize;
00150         TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
00151         t = length & wmask;
00152         TLOOP(*dst++ = *src++);
00153     } else {
00154         /*
00155          * Copy backwards.  Otherwise essentially the same.
00156          * Alignment works as before, except that it takes
00157          * (t&wmask) bytes to align, not wsize-(t&wmask).
00158          */
00159         src += length;
00160         dst += length;
00161         t = (long)src;
00162         if ((t | (long)dst) & wmask) {
00163             if ((t ^ (long)dst) & wmask || length <= wsize)
00164                 t = length;
00165             else
00166                 t &= wmask;
00167             length -= t;
00168             TLOOP1(*--dst = *--src);
00169         }
00170         t = length / wsize;
00171         TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
00172         t = length & wmask;
00173         TLOOP(*--dst = *--src);
00174     }
00175 done:
00176     return dst0;
00177 }
00178 

© 2000-2010 by contributors - visit http://www.ethernut.de/