1 /*
2 * Copyright (c) 2016, Alliance for Open Media. All rights reserved
3 *
4 * This source code is subject to the terms of the BSD 2 Clause License and
5 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
6 * was not distributed with this source code in the LICENSE file, you can
7 * obtain it at www.aomedia.org/license/software. If the Alliance for Open
8 * Media Patent License 1.0 was not distributed with this source code in the
9 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
10 */
11
12 #include "av1/encoder/hash.h"
13
crc_calculator_process_data(CRC_CALCULATOR * p_crc_calculator,uint8_t * pData,uint32_t dataLength)14 static void crc_calculator_process_data(CRC_CALCULATOR *p_crc_calculator,
15 uint8_t *pData, uint32_t dataLength) {
16 for (uint32_t i = 0; i < dataLength; i++) {
17 const uint8_t index =
18 (p_crc_calculator->remainder >> (p_crc_calculator->bits - 8)) ^
19 pData[i];
20 p_crc_calculator->remainder <<= 8;
21 p_crc_calculator->remainder ^= p_crc_calculator->table[index];
22 }
23 }
24
crc_calculator_reset(CRC_CALCULATOR * p_crc_calculator)25 static void crc_calculator_reset(CRC_CALCULATOR *p_crc_calculator) {
26 p_crc_calculator->remainder = 0;
27 }
28
crc_calculator_get_crc(CRC_CALCULATOR * p_crc_calculator)29 static uint32_t crc_calculator_get_crc(CRC_CALCULATOR *p_crc_calculator) {
30 return p_crc_calculator->remainder & p_crc_calculator->final_result_mask;
31 }
32
crc_calculator_init_table(CRC_CALCULATOR * p_crc_calculator)33 static void crc_calculator_init_table(CRC_CALCULATOR *p_crc_calculator) {
34 const uint32_t high_bit = 1 << (p_crc_calculator->bits - 1);
35 const uint32_t byte_high_bit = 1 << (8 - 1);
36
37 for (uint32_t value = 0; value < 256; value++) {
38 uint32_t remainder = 0;
39 for (uint8_t mask = byte_high_bit; mask != 0; mask >>= 1) {
40 if (value & mask) {
41 remainder ^= high_bit;
42 }
43
44 if (remainder & high_bit) {
45 remainder <<= 1;
46 remainder ^= p_crc_calculator->trunc_poly;
47 } else {
48 remainder <<= 1;
49 }
50 }
51 p_crc_calculator->table[value] = remainder;
52 }
53 }
54
av1_crc_calculator_init(CRC_CALCULATOR * p_crc_calculator,uint32_t bits,uint32_t truncPoly)55 void av1_crc_calculator_init(CRC_CALCULATOR *p_crc_calculator, uint32_t bits,
56 uint32_t truncPoly) {
57 p_crc_calculator->remainder = 0;
58 p_crc_calculator->bits = bits;
59 p_crc_calculator->trunc_poly = truncPoly;
60 p_crc_calculator->final_result_mask = (1 << bits) - 1;
61 crc_calculator_init_table(p_crc_calculator);
62 }
63
av1_get_crc_value(void * crc_calculator,uint8_t * p,int length)64 uint32_t av1_get_crc_value(void *crc_calculator, uint8_t *p, int length) {
65 CRC_CALCULATOR *p_crc_calculator = (CRC_CALCULATOR *)crc_calculator;
66 crc_calculator_reset(p_crc_calculator);
67 crc_calculator_process_data(p_crc_calculator, p, length);
68 return crc_calculator_get_crc(p_crc_calculator);
69 }
70
71 /* CRC-32C (iSCSI) polynomial in reversed bit order. */
72 #define POLY 0x82f63b78
73
74 /* Construct table for software CRC-32C calculation. */
av1_crc32c_calculator_init(CRC32C * p_crc32c)75 void av1_crc32c_calculator_init(CRC32C *p_crc32c) {
76 uint32_t crc;
77
78 for (int n = 0; n < 256; n++) {
79 crc = n;
80 crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
81 crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
82 crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
83 crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
84 crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
85 crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
86 crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
87 crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
88 p_crc32c->table[0][n] = crc;
89 }
90 for (int n = 0; n < 256; n++) {
91 crc = p_crc32c->table[0][n];
92 for (int k = 1; k < 8; k++) {
93 crc = p_crc32c->table[0][crc & 0xff] ^ (crc >> 8);
94 p_crc32c->table[k][n] = crc;
95 }
96 }
97 }
98
99 /* Table-driven software version as a fall-back. This is about 15 times slower
100 than using the hardware instructions. This assumes little-endian integers,
101 as is the case on Intel processors that the assembler code here is for. */
av1_get_crc32c_value_c(CRC32C * p,uint8_t * buf,size_t len)102 uint32_t av1_get_crc32c_value_c(CRC32C *p, uint8_t *buf, size_t len) {
103 const uint8_t *next = (const uint8_t *)(buf);
104 uint64_t crc;
105
106 crc = 0 ^ 0xffffffff;
107 while (len && ((uintptr_t)next & 7) != 0) {
108 crc = p->table[0][(crc ^ *next++) & 0xff] ^ (crc >> 8);
109 len--;
110 }
111 while (len >= 8) {
112 crc ^= *(uint64_t *)next;
113 crc = p->table[7][crc & 0xff] ^ p->table[6][(crc >> 8) & 0xff] ^
114 p->table[5][(crc >> 16) & 0xff] ^ p->table[4][(crc >> 24) & 0xff] ^
115 p->table[3][(crc >> 32) & 0xff] ^ p->table[2][(crc >> 40) & 0xff] ^
116 p->table[1][(crc >> 48) & 0xff] ^ p->table[0][crc >> 56];
117 next += 8;
118 len -= 8;
119 }
120 while (len) {
121 crc = p->table[0][(crc ^ *next++) & 0xff] ^ (crc >> 8);
122 len--;
123 }
124 return (uint32_t)crc ^ 0xffffffff;
125 }
126