FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavutil/x86/crc.h
Date: 2026-05-03 03:13:14
Exec Total Coverage
Lines: 32 42 76.2%
Functions: 4 4 100.0%
Branches: 8 11 72.7%

Line Branch Exec Source
1 /*
2 * Copyright (c) 2025 Shreesh Adiga <16567adigashreesh@gmail.com>
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 #ifndef AVUTIL_X86_CRC_H
22 #define AVUTIL_X86_CRC_H
23
24 #include "config.h"
25 #include "libavutil/attributes.h"
26 #include "libavutil/attributes_internal.h"
27 #include "libavutil/avassert.h"
28 #include "libavutil/cpu.h"
29 #include "libavutil/crc.h"
30 #include "libavutil/intreadwrite.h"
31 #include "libavutil/x86/cpu.h"
32
33 #if HAVE_CLMUL_EXTERNAL
34 #include "libavutil/crc_internal.h"
35
36 FF_VISIBILITY_PUSH_HIDDEN
37 uint32_t ff_crc_clmul(const AVCRC *ctx, uint32_t crc,
38 const uint8_t *buffer, size_t length);
39 uint32_t ff_crc_le_clmul(const AVCRC *ctx, uint32_t crc,
40 const uint8_t *buffer, size_t length);
41 FF_VISIBILITY_POP_HIDDEN
42
43 enum {
44 CRC_C = 0,
45 CLMUL_BE,
46 CLMUL_LE,
47 };
48
49 static const AVCRC crc_table_clmul[AV_CRC_MAX][17] = {
50 [AV_CRC_8_ATM] = {
51 CLMUL_BE,
52 0x32000000, 0x0, 0xbc000000, 0x0,
53 0xc4000000, 0x0, 0x94000000, 0x0,
54 0x62000000, 0x0, 0x79000000, 0x0,
55 0x07156a16, 0x1, 0x07000000, 0x1,
56 },
57 [AV_CRC_8_EBU] = {
58 CLMUL_BE,
59 0xb5000000, 0x0, 0xf3000000, 0x0,
60 0xfc000000, 0x0, 0x0d000000, 0x0,
61 0x6a000000, 0x0, 0x65000000, 0x0,
62 0x1c4b8192, 0x1, 0x1d000000, 0x1,
63 },
64 [AV_CRC_16_ANSI] = {
65 CLMUL_BE,
66 0xf9e30000, 0x0, 0x807d0000, 0x0,
67 0xf9130000, 0x0, 0xff830000, 0x0,
68 0x807b0000, 0x0, 0x86630000, 0x0,
69 0xfffbffe7, 0x1, 0x80050000, 0x1,
70 },
71 [AV_CRC_16_CCITT] = {
72 CLMUL_BE,
73 0x60190000, 0x0, 0x59b00000, 0x0,
74 0xd5f60000, 0x0, 0x45630000, 0x0,
75 0xaa510000, 0x0, 0xeb230000, 0x0,
76 0x11303471, 0x1, 0x10210000, 0x1,
77 },
78 [AV_CRC_24_IEEE] = {
79 CLMUL_BE,
80 0x1f428700, 0x0, 0x467d2400, 0x0,
81 0x2c8c9d00, 0x0, 0x64e4d700, 0x0,
82 0xd9fe8c00, 0x0, 0xfd7e0c00, 0x0,
83 0xf845fe24, 0x1, 0x864cfb00, 0x1,
84 },
85 [AV_CRC_32_IEEE] = {
86 CLMUL_BE,
87 0x8833794c, 0x0, 0xe6228b11, 0x0,
88 0xc5b9cd4c, 0x0, 0xe8a45605, 0x0,
89 0x490d678d, 0x0, 0xf200aa66, 0x0,
90 0x04d101df, 0x1, 0x04c11db7, 0x1,
91 },
92 [AV_CRC_32_IEEE_LE] = {
93 CLMUL_LE,
94 0xc6e41596, 0x1, 0x54442bd4, 0x1,
95 0xccaa009e, 0x0, 0x751997d0, 0x1,
96 0xccaa009e, 0x0, 0x63cd6124, 0x1,
97 0xf7011640, 0x1, 0xdb710641, 0x1,
98 },
99 [AV_CRC_16_ANSI_LE] = {
100 CLMUL_LE,
101 0x0000bffa, 0x0, 0x1b0c2, 0x0,
102 0x00018cc2, 0x0, 0x1d0c2, 0x0,
103 0x00018cc2, 0x0, 0x1bc02, 0x0,
104 0xcfffbffe, 0x1, 0x14003, 0x0,
105 },
106 };
107
108 4 static inline void crc_init_x86(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size)
109 {
110 uint64_t poly_;
111
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4 if (le) {
112 // convert the reversed representation to regular form
113 4 poly = reverse(poly, bits) >> 1;
114 }
115 // convert to 32 degree polynomial
116 4 poly_ = ((uint64_t)poly) << (32 - bits);
117
118 uint64_t div;
119 4 uint8_t *dst = (uint8_t*)(ctx + 1);
120
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4 if (le) {
121 4 ctx[0] = CLMUL_LE;
122 4 AV_WN64(dst, xnmodp(4 * 128 - 32, poly_, 32, &div, le));
123 4 AV_WN64(dst + 8, xnmodp(4 * 128 + 32, poly_, 32, &div, le));
124 4 uint64_t tmp = xnmodp(128 - 32, poly_, 32, &div, le);
125 4 AV_WN64(dst + 16, tmp);
126 4 AV_WN64(dst + 24, xnmodp(128 + 32, poly_, 32, &div, le));
127 4 AV_WN64(dst + 32, tmp);
128 4 AV_WN64(dst + 40, xnmodp(64, poly_, 32, &div, le));
129 4 AV_WN64(dst + 48, div);
130 4 AV_WN64(dst + 56, reverse(poly_ | (1ULL << 32), 32));
131 } else {
132 ctx[0] = CLMUL_BE;
133 AV_WN64(dst, xnmodp(4 * 128 + 64, poly_, 32, &div, le));
134 AV_WN64(dst + 8, xnmodp(4 * 128, poly_, 32, &div, le));
135 AV_WN64(dst + 16, xnmodp(128 + 64, poly_, 32, &div, le));
136 AV_WN64(dst + 24, xnmodp(128, poly_, 32, &div, le));
137 AV_WN64(dst + 32, xnmodp(64, poly_, 32, &div, le));
138 AV_WN64(dst + 48, div);
139 AV_WN64(dst + 40, xnmodp(96, poly_, 32, &div, le));
140 AV_WN64(dst + 56, poly_ | (1ULL << 32));
141 }
142 4 }
143 #endif
144
145 208215 static inline const AVCRC *ff_crc_get_table_x86(AVCRCId crc_id)
146 {
147 #if HAVE_CLMUL_EXTERNAL
148 208215 int cpu_flags = av_get_cpu_flags();
149
150
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208215 if (EXTERNAL_CLMUL(cpu_flags)) {
151 18573 return crc_table_clmul[crc_id];
152 }
153 #endif
154 189642 return NULL;
155 }
156
157 3790 static inline av_cold int ff_crc_init_x86(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size)
158 {
159 #if HAVE_CLMUL_EXTERNAL
160 3790 int cpu_flags = av_get_cpu_flags();
161
162
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3790 if (EXTERNAL_CLMUL(cpu_flags)) {
163 4 crc_init_x86(ctx, le, bits, poly, ctx_size);
164 4 return 1;
165 }
166 #endif
167 3786 return 0;
168 }
169
170 20841 static inline uint32_t ff_crc_x86(const AVCRC *ctx, uint32_t crc,
171 const uint8_t *buffer, size_t length)
172 {
173
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20841 switch (ctx[0]) {
174 #if HAVE_CLMUL_EXTERNAL
175 17965 case CLMUL_BE: return ff_crc_clmul(ctx, crc, buffer, length);
176 2876 case CLMUL_LE: return ff_crc_le_clmul(ctx, crc, buffer, length);
177 #endif
178 default: av_unreachable("x86 CRC only uses CLMUL_BE and CLMUL_LE");
179 }
180 return 0;
181 }
182
183 #endif /* AVUTIL_X86_CRC_H */
184