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/*
* Copyright (c) 2016, Alliance for Open Media. All rights reserved
*
* This source code is subject to the terms of the BSD 2 Clause License and
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
* was not distributed with this source code in the LICENSE file, you can
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
* Media Patent License 1.0 was not distributed with this source code in the
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
*/
#include "av1/encoder/hash.h"
static void crc_calculator_process_data(CRC_CALCULATOR *p_crc_calculator,
uint8_t *pData, uint32_t dataLength) {
for (uint32_t i = 0; i < dataLength; i++) {
const uint8_t index = (uint8_t)(
(p_crc_calculator->remainder >> (p_crc_calculator->bits - 8)) ^
pData[i]);
p_crc_calculator->remainder <<= 8;
p_crc_calculator->remainder ^= p_crc_calculator->table[index];
}
}
static void crc_calculator_reset(CRC_CALCULATOR *p_crc_calculator) {
p_crc_calculator->remainder = 0;
}
static uint32_t crc_calculator_get_crc(CRC_CALCULATOR *p_crc_calculator) {
return p_crc_calculator->remainder & p_crc_calculator->final_result_mask;
}
static void crc_calculator_init_table(CRC_CALCULATOR *p_crc_calculator) {
const uint32_t high_bit = 1 << (p_crc_calculator->bits - 1);
const uint32_t byte_high_bit = 1 << (8 - 1);
for (uint32_t value = 0; value < 256; value++) {
uint32_t remainder = 0;
for (uint8_t mask = byte_high_bit; mask != 0; mask >>= 1) {
if (value & mask) {
remainder ^= high_bit;
}
if (remainder & high_bit) {
remainder <<= 1;
remainder ^= p_crc_calculator->trunc_poly;
} else {
remainder <<= 1;
}
}
p_crc_calculator->table[value] = remainder;
}
}
void av1_crc_calculator_init(CRC_CALCULATOR *p_crc_calculator, uint32_t bits,
uint32_t truncPoly) {
p_crc_calculator->remainder = 0;
p_crc_calculator->bits = bits;
p_crc_calculator->trunc_poly = truncPoly;
p_crc_calculator->final_result_mask = (1 << bits) - 1;
crc_calculator_init_table(p_crc_calculator);
}
uint32_t av1_get_crc_value(CRC_CALCULATOR *p_crc_calculator, uint8_t *p,
int length) {
crc_calculator_reset(p_crc_calculator);
crc_calculator_process_data(p_crc_calculator, p, length);
return crc_calculator_get_crc(p_crc_calculator);
}
/* CRC-32C (iSCSI) polynomial in reversed bit order. */
#define POLY 0x82f63b78
/* Construct table for software CRC-32C calculation. */
void av1_crc32c_calculator_init(CRC32C *p_crc32c) {
uint32_t crc;
for (int n = 0; n < 256; n++) {
crc = n;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
p_crc32c->table[0][n] = crc;
}
for (int n = 0; n < 256; n++) {
crc = p_crc32c->table[0][n];
for (int k = 1; k < 8; k++) {
crc = p_crc32c->table[0][crc & 0xff] ^ (crc >> 8);
p_crc32c->table[k][n] = crc;
}
}
}
/* Table-driven software version as a fall-back. This is about 15 times slower
than using the hardware instructions. This assumes little-endian integers,
as is the case on Intel processors that the assembler code here is for. */
uint32_t av1_get_crc32c_value_c(void *c, uint8_t *buf, size_t len) {
const uint8_t *next = (const uint8_t *)(buf);
uint64_t crc;
CRC32C *p = (CRC32C *)c;
crc = 0 ^ 0xffffffff;
while (len && ((uintptr_t)next & 7) != 0) {
crc = p->table[0][(crc ^ *next++) & 0xff] ^ (crc >> 8);
len--;
}
while (len >= 8) {
crc ^= *(uint64_t *)next;
crc = p->table[7][crc & 0xff] ^ p->table[6][(crc >> 8) & 0xff] ^
p->table[5][(crc >> 16) & 0xff] ^ p->table[4][(crc >> 24) & 0xff] ^
p->table[3][(crc >> 32) & 0xff] ^ p->table[2][(crc >> 40) & 0xff] ^
p->table[1][(crc >> 48) & 0xff] ^ p->table[0][crc >> 56];
next += 8;
len -= 8;
}
while (len) {
crc = p->table[0][(crc ^ *next++) & 0xff] ^ (crc >> 8);
len--;
}
return (uint32_t)crc ^ 0xffffffff;
}
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