Annotation of embedaddon/ntp/libntp/memmove.c, revision 1.1
1.1 ! misho 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. All advertising materials mentioning features or use of this software
! 17: * must display the following acknowledgement:
! 18: * This product includes software developed by the University of
! 19: * California, Berkeley and its contributors.
! 20: * 4. Neither the name of the University nor the names of its contributors
! 21: * may be used to endorse or promote products derived from this software
! 22: * without specific prior written permission.
! 23: *
! 24: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 25: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 26: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 27: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 28: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 29: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 30: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 31: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 32: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 33: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 34: * SUCH DAMAGE.
! 35: */
! 36:
! 37: #if defined(LIBC_SCCS) && !defined(lint)
! 38: static char sccsid[] = "@(#)bcopy.c 8.1 (Berkeley) 6/4/93";
! 39: #endif /* LIBC_SCCS and not lint */
! 40:
! 41: #ifdef HAVE_CONFIG_H
! 42: # include <config.h>
! 43: #endif
! 44:
! 45: #ifndef HAVE_MEMMOVE
! 46: #ifdef HAVE_SYS_TYPES_H
! 47: #include <sys/types.h>
! 48: #endif
! 49: #include <string.h>
! 50:
! 51: #include "l_stdlib.h"
! 52:
! 53: /*
! 54: * sizeof(word) MUST BE A POWER OF TWO
! 55: * SO THAT wmask BELOW IS ALL ONES
! 56: */
! 57: typedef int word; /* "word" used for optimal copy speed */
! 58:
! 59: #define wsize sizeof(word)
! 60: #define wmask (wsize - 1)
! 61:
! 62: /*
! 63: * Copy a block of memory, handling overlap.
! 64: * This is the routine that actually implements
! 65: * (the portable versions of) bcopy, memcpy, and memmove.
! 66: */
! 67: void *
! 68: memmove(
! 69: void *dst0,
! 70: const void *src0,
! 71: register size_t length
! 72: )
! 73: {
! 74: register char *dst = dst0;
! 75: register const char *src = src0;
! 76: register size_t t;
! 77:
! 78: if (length == 0 || dst == src) /* nothing to do */
! 79: goto done;
! 80:
! 81: /*
! 82: * Macros: loop-t-times; and loop-t-times, t>0
! 83: */
! 84: #define TLOOP(s) if (t) TLOOP1(s)
! 85: #define TLOOP1(s) do { s; } while (--t)
! 86:
! 87: if ((unsigned long)dst < (unsigned long)src) {
! 88: /*
! 89: * Copy forward.
! 90: */
! 91: t = (int)src; /* only need low bits */
! 92: if ((t | (int)dst) & wmask) {
! 93: /*
! 94: * Try to align operands. This cannot be done
! 95: * unless the low bits match.
! 96: */
! 97: if ((t ^ (int)dst) & wmask || length < wsize)
! 98: t = length;
! 99: else
! 100: t = wsize - (t & wmask);
! 101: length -= t;
! 102: TLOOP1(*dst++ = *src++);
! 103: }
! 104: /*
! 105: * Copy whole words, then mop up any trailing bytes.
! 106: */
! 107: t = length / wsize;
! 108: TLOOP(*(word *)dst = *(const word *)src; src += wsize;
! 109: dst += wsize);
! 110: t = length & wmask;
! 111: TLOOP(*dst++ = *src++);
! 112: } else {
! 113: /*
! 114: * Copy backwards. Otherwise essentially the same.
! 115: * Alignment works as before, except that it takes
! 116: * (t&wmask) bytes to align, not wsize-(t&wmask).
! 117: */
! 118: src += length;
! 119: dst += length;
! 120: t = (int)src;
! 121: if ((t | (int)dst) & wmask) {
! 122: if ((t ^ (int)dst) & wmask || length <= wsize)
! 123: t = length;
! 124: else
! 125: t &= wmask;
! 126: length -= t;
! 127: TLOOP1(*--dst = *--src);
! 128: }
! 129: t = length / wsize;
! 130: TLOOP(src -= wsize; dst -= wsize;
! 131: *(word *)dst = *(const word *)src);
! 132: t = length & wmask;
! 133: TLOOP(*--dst = *--src);
! 134: }
! 135: done:
! 136: return (dst0);
! 137: }
! 138: #else
! 139: int memmove_bs;
! 140: #endif
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