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# bcopy.c

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    00001 /*-
    00002  * Copyright (c) 1990, 1993
    00003  *      The Regents of the University of California.  All rights reserved.
    00004  *
    00005  * This code is derived from software contributed to Berkeley by
    00006  * Chris Torek.
    00007  *
    00008  * Redistribution and use in source and binary forms, with or without
    00009  * modification, are permitted provided that the following conditions
    00010  * are met:
    00011  * 1. Redistributions of source code must retain the above copyright
    00012  *    notice, this list of conditions and the following disclaimer.
    00013  * 2. Redistributions in binary form must reproduce the above copyright
    00014  *    notice, this list of conditions and the following disclaimer in the
    00015  *    documentation and/or other materials provided with the distribution.
    00016  * 3. All advertising materials mentioning features or use of this software
    00017  *    must display the following acknowledgement:
    00018  *      This product includes software developed by the University of
    00019  *      California, Berkeley and its contributors.
    00020  * 4. Neither the name of the University nor the names of its contributors
    00021  *    may be used to endorse or promote products derived from this software
    00022  *    without specific prior written permission.
    00023  *
    00024  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
    00025  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    00026  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
    00027  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
    00028  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
    00029  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
    00030  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
    00031  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
    00032  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
    00033  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
    00034  * SUCH DAMAGE.
    00035  *
    00036  * $ID: $
    00037  */
    00038
    00039 #include <ubixos/types.h>
    00040
    00041 /*
    00042  * sizeof(word) MUST BE A POWER OF TWO
    00043  * SO THAT wmask BELOW IS ALL ONES
    00044  */
    00045 typedef int word;               /* "word" used for optimal copy speed */
    00046 typedef u_int32_t uintptr_t;
    00047
    00048 #define wsize   sizeof(word)
    00049 #define wmask   (wsize - 1)
    00050
    00051 /*
    00052  * Copy a block of memory, handling overlap.
    00053  * This is the routine that actually implements
    00054  * (the portable versions of) bcopy, memcpy, and memmove.
    00055  */
    00056 #if defined(MEMCOPY) || defined(MEMMOVE)
    00057 #include <string.h>
    00058
    00059 void *
    00060 #ifdef MEMCOPY
    00061 memcpy
    00062 #else
    00063 memmove
    00064 #endif
    00065 (void *dst0, const void *src0, size_t length)
    00066 #else
    00067 #include <strings.h>
    00068
    00069 void
    00070 bcopy(const void *src0, void *dst0, size_t length)
    00071 #endif
    00072 {
    00073         char *dst = dst0;
    00074         const char *src = src0;
    00075         size_t t;
    00076
    00077         if (length == 0 || dst == src)          /* nothing to do */
    00078                 goto done;
    00079
    00080         /*
    00081          * Macros: loop-t-times; and loop-t-times, t>0
    00082          */
    00083 #define TLOOP(s) if (t) TLOOP1(s)
    00084 #define TLOOP1(s) do { s; } while (--t)
    00085
    00086         if ((unsigned long)dst < (unsigned long)src) {
    00087                 /*
    00088                  * Copy forward.
    00089                  */
    00090                 t = (uintptr_t)src;     /* only need low bits */
    00091                 if ((t | (uintptr_t)dst) & wmask) {
    00092                         /*
    00093                          * Try to align operands.  This cannot be done
    00094                          * unless the low bits match.
    00095                          */
    00096                         if ((t ^ (uintptr_t)dst) & wmask || length < wsize)
    00097                                 t = length;
    00098                         else
    00099                                 t = wsize - (t & wmask);
    00100                         length -= t;
    00101                         TLOOP1(*dst++ = *src++);
    00102                 }
    00103                 /*
    00104                  * Copy whole words, then mop up any trailing bytes.
    00105                  */
    00106                 t = length / wsize;
    00107                 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
    00108                 t = length & wmask;
    00109                 TLOOP(*dst++ = *src++);
    00110         } else {
    00111                 /*
    00112                  * Copy backwards.  Otherwise essentially the same.
    00113                  * Alignment works as before, except that it takes
    00114                  * (t&wmask) bytes to align, not wsize-(t&wmask).
    00115                  */
    00116                 src += length;
    00117                 dst += length;
    00118                 t = (uintptr_t)src;
    00119                 if ((t | (uintptr_t)dst) & wmask) {
    00120                         if ((t ^ (uintptr_t)dst) & wmask || length <= wsize)
    00121                                 t = length;
    00122                         else
    00123                                 t &= wmask;
    00124                         length -= t;
    00125                         TLOOP1(*--dst = *--src);
    00126                 }
    00127                 t = length / wsize;
    00128                 TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
    00129                 t = length & wmask;
    00130                 TLOOP(*--dst = *--src);
    00131         }
    00132 done:
    00133 #if defined(MEMCOPY) || defined(MEMMOVE)
    00134         return (dst0);
    00135 #else
    00136         return;
    00137 #endif
    00138 }