Annotation of embedaddon/ntp/libntp/memmove.c, revision 1.1.1.1
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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