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      1 /*-
      2  * Copyright (c) 1990, 1993
      3  *	The Regents of the University of California.  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  * 3. 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 #include <sys/cdefs.h>
     34 __FBSDID("$FreeBSD$");
     35 
     36 #include <stdint.h>
     37 #include <sys/types.h>
     38 
     39 /*
     40  * sizeof(word) MUST BE A POWER OF TWO
     41  * SO THAT wmask BELOW IS ALL ONES
     42  */
     43 typedef	int word;		/* "word" used for optimal copy speed */
     44 
     45 #define	wsize	sizeof(word)
     46 #define	wmask	(wsize - 1)
     47 
     48 /*
     49  * Copy a block of memory, handling overlap.
     50  * This is the routine that actually implements
     51  * (the portable versions of) bcopy, memcpy, and memmove.
     52  */
     53 #if defined(MEMCOPY) || defined(MEMMOVE)
     54 #include <string.h>
     55 
     56 void *
     57 #ifdef MEMCOPY
     58 memcpy
     59 #else
     60 memmove
     61 #endif
     62 (void *dst0, const void *src0, size_t length)
     63 #else
     64 #include <strings.h>
     65 
     66 void
     67 bcopy(const void *src0, void *dst0, size_t length)
     68 #endif
     69 {
     70 	char *dst = dst0;
     71 	const char *src = src0;
     72 	size_t t;
     73 
     74 	if (length == 0 || dst == src)		/* nothing to do */
     75 		goto done;
     76 
     77 	/*
     78 	 * Macros: loop-t-times; and loop-t-times, t>0
     79 	 */
     80 #define	TLOOP(s) if (t) TLOOP1(s)
     81 #define	TLOOP1(s) do { s; } while (--t)
     82 
     83 	if ((unsigned long)dst < (unsigned long)src) {
     84 		/*
     85 		 * Copy forward.
     86 		 */
     87 		t = (uintptr_t)src;	/* only need low bits */
     88 		if ((t | (uintptr_t)dst) & wmask) {
     89 			/*
     90 			 * Try to align operands.  This cannot be done
     91 			 * unless the low bits match.
     92 			 */
     93 			if ((t ^ (uintptr_t)dst) & wmask || length < wsize)
     94 				t = length;
     95 			else
     96 				t = wsize - (t & wmask);
     97 			length -= t;
     98 			TLOOP1(*dst++ = *src++);
     99 		}
    100 		/*
    101 		 * Copy whole words, then mop up any trailing bytes.
    102 		 */
    103 		t = length / wsize;
    104 		TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
    105 		t = length & wmask;
    106 		TLOOP(*dst++ = *src++);
    107 	} else {
    108 		/*
    109 		 * Copy backwards.  Otherwise essentially the same.
    110 		 * Alignment works as before, except that it takes
    111 		 * (t&wmask) bytes to align, not wsize-(t&wmask).
    112 		 */
    113 		src += length;
    114 		dst += length;
    115 		t = (uintptr_t)src;
    116 		if ((t | (uintptr_t)dst) & wmask) {
    117 			if ((t ^ (uintptr_t)dst) & wmask || length <= wsize)
    118 				t = length;
    119 			else
    120 				t &= wmask;
    121 			length -= t;
    122 			TLOOP1(*--dst = *--src);
    123 		}
    124 		t = length / wsize;
    125 		TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
    126 		t = length & wmask;
    127 		TLOOP(*--dst = *--src);
    128 	}
    129 done:
    130 #if defined(MEMCOPY) || defined(MEMMOVE)
    131 	return (dst0);
    132 #else
    133 	return;
    134 #endif
    135 }
    136