blob: b1ef7cad6ce1fd56037520649e8aa09b7e3f065e [file] [log] [blame]
Kaido Kert25902c62024-06-17 17:10:28 -07001// Copyright (c) 2012 The WebM project authors. All Rights Reserved.
2//
3// Use of this source code is governed by a BSD-style license
4// that can be found in the LICENSE file in the root of the source
5// tree. An additional intellectual property rights grant can be found
6// in the file PATENTS. All contributing project authors may
7// be found in the AUTHORS file in the root of the source tree.
8
9#include "common/webm_endian.h"
10
11#include <stdint.h>
12
13namespace {
14
15// Swaps unsigned 32 bit values to big endian if needed. Returns |value|
16// unmodified if architecture is big endian. Returns swapped bytes of |value|
17// if architecture is little endian. Returns 0 otherwise.
18uint32_t swap32_check_little_endian(uint32_t value) {
19 // Check endianness.
20 union {
21 uint32_t val32;
22 uint8_t c[4];
23 } check;
24 check.val32 = 0x01234567U;
25
26 // Check for big endian.
27 if (check.c[3] == 0x67)
28 return value;
29
30 // Check for not little endian.
31 if (check.c[0] != 0x67)
32 return 0;
33
34 return value << 24 | ((value << 8) & 0x0000FF00U) |
35 ((value >> 8) & 0x00FF0000U) | value >> 24;
36}
37
38// Swaps unsigned 64 bit values to big endian if needed. Returns |value|
39// unmodified if architecture is big endian. Returns swapped bytes of |value|
40// if architecture is little endian. Returns 0 otherwise.
41uint64_t swap64_check_little_endian(uint64_t value) {
42 // Check endianness.
43 union {
44 uint64_t val64;
45 uint8_t c[8];
46 } check;
47 check.val64 = 0x0123456789ABCDEFULL;
48
49 // Check for big endian.
50 if (check.c[7] == 0xEF)
51 return value;
52
53 // Check for not little endian.
54 if (check.c[0] != 0xEF)
55 return 0;
56
57 return value << 56 | ((value << 40) & 0x00FF000000000000ULL) |
58 ((value << 24) & 0x0000FF0000000000ULL) |
59 ((value << 8) & 0x000000FF00000000ULL) |
60 ((value >> 8) & 0x00000000FF000000ULL) |
61 ((value >> 24) & 0x0000000000FF0000ULL) |
62 ((value >> 40) & 0x000000000000FF00ULL) | value >> 56;
63}
64
65} // namespace
66
67namespace libwebm {
68
69uint32_t host_to_bigendian(uint32_t value) {
70 return swap32_check_little_endian(value);
71}
72
73uint32_t bigendian_to_host(uint32_t value) {
74 return swap32_check_little_endian(value);
75}
76
77uint64_t host_to_bigendian(uint64_t value) {
78 return swap64_check_little_endian(value);
79}
80
81uint64_t bigendian_to_host(uint64_t value) {
82 return swap64_check_little_endian(value);
83}
84
85} // namespace libwebm