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 #include "config/av1_rtcd.h"
14
crc_calculator_process_data(CRC_CALCULATOR * p_crc_calculator,uint8_t * pData,uint32_t dataLength)15 static void crc_calculator_process_data(CRC_CALCULATOR *p_crc_calculator,
16 uint8_t *pData, uint32_t dataLength) {
17 for (uint32_t i = 0; i < dataLength; i++) {
18 const uint8_t index = (uint8_t)((p_crc_calculator->remainder >>
19 (p_crc_calculator->bits - 8)) ^
20 pData[i]);
21 p_crc_calculator->remainder <<= 8;
22 p_crc_calculator->remainder ^= p_crc_calculator->table[index];
23 }
24 }
25
crc_calculator_reset(CRC_CALCULATOR * p_crc_calculator)26 static void crc_calculator_reset(CRC_CALCULATOR *p_crc_calculator) {
27 p_crc_calculator->remainder = 0;
28 }
29
crc_calculator_get_crc(CRC_CALCULATOR * p_crc_calculator)30 static uint32_t crc_calculator_get_crc(CRC_CALCULATOR *p_crc_calculator) {
31 return p_crc_calculator->remainder & p_crc_calculator->final_result_mask;
32 }
33
crc_calculator_init_table(CRC_CALCULATOR * p_crc_calculator)34 static void crc_calculator_init_table(CRC_CALCULATOR *p_crc_calculator) {
35 const uint32_t high_bit = 1 << (p_crc_calculator->bits - 1);
36 const uint32_t byte_high_bit = 1 << (8 - 1);
37
38 for (uint32_t value = 0; value < 256; value++) {
39 uint32_t remainder = 0;
40 for (uint8_t mask = byte_high_bit; mask != 0; mask >>= 1) {
41 if (value & mask) {
42 remainder ^= high_bit;
43 }
44
45 if (remainder & high_bit) {
46 remainder <<= 1;
47 remainder ^= p_crc_calculator->trunc_poly;
48 } else {
49 remainder <<= 1;
50 }
51 }
52 p_crc_calculator->table[value] = remainder;
53 }
54 }
55
av1_crc_calculator_init(CRC_CALCULATOR * p_crc_calculator,uint32_t bits,uint32_t truncPoly)56 void av1_crc_calculator_init(CRC_CALCULATOR *p_crc_calculator, uint32_t bits,
57 uint32_t truncPoly) {
58 p_crc_calculator->remainder = 0;
59 p_crc_calculator->bits = bits;
60 p_crc_calculator->trunc_poly = truncPoly;
61 p_crc_calculator->final_result_mask = (1 << bits) - 1;
62 crc_calculator_init_table(p_crc_calculator);
63 }
64
av1_get_crc_value(CRC_CALCULATOR * p_crc_calculator,uint8_t * p,int length)65 uint32_t av1_get_crc_value(CRC_CALCULATOR *p_crc_calculator, uint8_t *p,
66 int length) {
67 crc_calculator_reset(p_crc_calculator);
68 crc_calculator_process_data(p_crc_calculator, p, length);
69 return crc_calculator_get_crc(p_crc_calculator);
70 }
71
72 /* CRC-32C (iSCSI) polynomial in reversed bit order. */
73 #define POLY 0x82f63b78
74
75 /* Construct table for software CRC-32C calculation. */
av1_crc32c_calculator_init(CRC32C * p_crc32c)76 void av1_crc32c_calculator_init(CRC32C *p_crc32c) {
77 uint32_t crc;
78
79 for (int n = 0; n < 256; n++) {
80 crc = n;
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 crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
89 p_crc32c->table[0][n] = crc;
90 }
91 for (int n = 0; n < 256; n++) {
92 crc = p_crc32c->table[0][n];
93 for (int k = 1; k < 8; k++) {
94 crc = p_crc32c->table[0][crc & 0xff] ^ (crc >> 8);
95 p_crc32c->table[k][n] = crc;
96 }
97 }
98 }
99
100 /* Table-driven software version as a fall-back. This is about 15 times slower
101 than using the hardware instructions. This assumes little-endian integers,
102 as is the case on Intel processors that the assembler code here is for. */
av1_get_crc32c_value_c(void * c,uint8_t * buf,size_t len)103 uint32_t av1_get_crc32c_value_c(void *c, uint8_t *buf, size_t len) {
104 const uint8_t *next = (const uint8_t *)(buf);
105 uint64_t crc;
106 CRC32C *p = (CRC32C *)c;
107 crc = 0 ^ 0xffffffff;
108 while (len && ((uintptr_t)next & 7) != 0) {
109 crc = p->table[0][(crc ^ *next++) & 0xff] ^ (crc >> 8);
110 len--;
111 }
112 while (len >= 8) {
113 crc ^= *(uint64_t *)next;
114 crc = p->table[7][crc & 0xff] ^ p->table[6][(crc >> 8) & 0xff] ^
115 p->table[5][(crc >> 16) & 0xff] ^ p->table[4][(crc >> 24) & 0xff] ^
116 p->table[3][(crc >> 32) & 0xff] ^ p->table[2][(crc >> 40) & 0xff] ^
117 p->table[1][(crc >> 48) & 0xff] ^ p->table[0][crc >> 56];
118 next += 8;
119 len -= 8;
120 }
121 while (len) {
122 crc = p->table[0][(crc ^ *next++) & 0xff] ^ (crc >> 8);
123 len--;
124 }
125 return (uint32_t)crc ^ 0xffffffff;
126 }
127