1 : /* endinconv.c -- Endian conversions utilities.
2 : *
3 : * This functions are never called directly, but always using the macros
4 : * defined into endianconv.h, this way we define everything is a non-operation
5 : * if the arch is already little endian.
6 : *
7 : * Redis tries to encode everything as little endian (but a few things that need
8 : * to be backward compatible are still in big endian) because most of the
9 : * production environments are little endian, and we have a lot of conversions
10 : * in a few places because ziplists, intsets, zipmaps, need to be endian-neutral
11 : * even in memory, since they are serialied on RDB files directly with a single
12 : * write(2) without other additional steps.
13 : *
14 : * ----------------------------------------------------------------------------
15 : *
16 : * Copyright (c) 2011-2012, Salvatore Sanfilippo <antirez at gmail dot com>
17 : * All rights reserved.
18 : *
19 : * Redistribution and use in source and binary forms, with or without
20 : * modification, are permitted provided that the following conditions are met:
21 : *
22 : * * Redistributions of source code must retain the above copyright notice,
23 : * this list of conditions and the following disclaimer.
24 : * * Redistributions in binary form must reproduce the above copyright
25 : * notice, this list of conditions and the following disclaimer in the
26 : * documentation and/or other materials provided with the distribution.
27 : * * Neither the name of Redis nor the names of its contributors may be used
28 : * to endorse or promote products derived from this software without
29 : * specific prior written permission.
30 : *
31 : * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
32 : * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
33 : * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
34 : * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
35 : * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
36 : * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
37 : * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
38 : * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
39 : * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 : * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
41 : * POSSIBILITY OF SUCH DAMAGE.
42 : */
43 :
44 :
45 : #include <stdint.h>
46 :
47 : /* Toggle the 16 bit unsigned integer pointed by *p from little endian to
48 : * big endian */
49 0 : void memrev16(void *p) {
50 0 : unsigned char *x = p, t;
51 :
52 0 : t = x[0];
53 0 : x[0] = x[1];
54 0 : x[1] = t;
55 0 : }
56 :
57 : /* Toggle the 32 bit unsigned integer pointed by *p from little endian to
58 : * big endian */
59 0 : void memrev32(void *p) {
60 0 : unsigned char *x = p, t;
61 :
62 0 : t = x[0];
63 0 : x[0] = x[3];
64 0 : x[3] = t;
65 0 : t = x[1];
66 0 : x[1] = x[2];
67 0 : x[2] = t;
68 0 : }
69 :
70 : /* Toggle the 64 bit unsigned integer pointed by *p from little endian to
71 : * big endian */
72 0 : void memrev64(void *p) {
73 0 : unsigned char *x = p, t;
74 :
75 0 : t = x[0];
76 0 : x[0] = x[7];
77 0 : x[7] = t;
78 0 : t = x[1];
79 0 : x[1] = x[6];
80 0 : x[6] = t;
81 0 : t = x[2];
82 0 : x[2] = x[5];
83 0 : x[5] = t;
84 0 : t = x[3];
85 0 : x[3] = x[4];
86 0 : x[4] = t;
87 0 : }
88 :
89 0 : uint16_t intrev16(uint16_t v) {
90 : memrev16(&v);
91 0 : return v;
92 : }
93 :
94 0 : uint32_t intrev32(uint32_t v) {
95 : memrev32(&v);
96 0 : return v;
97 : }
98 :
99 0 : uint64_t intrev64(uint64_t v) {
100 0 : memrev64(&v);
101 0 : return v;
102 : }
103 :
104 : #ifdef TESTMAIN
105 : #include <stdio.h>
106 :
107 : int main(void) {
108 : char buf[32];
109 :
110 : sprintf(buf,"ciaoroma");
111 : memrev16(buf);
112 : printf("%s\n", buf);
113 :
114 : sprintf(buf,"ciaoroma");
115 : memrev32(buf);
116 : printf("%s\n", buf);
117 :
118 : sprintf(buf,"ciaoroma");
119 : memrev64(buf);
120 : printf("%s\n", buf);
121 :
122 : return 0;
123 : }
124 : #endif
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