126 lines
4.4 KiB
C
126 lines
4.4 KiB
C
/*
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* Copyright (c) 2016, Alliance for Open Media. All rights reserved.
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*
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* This source code is subject to the terms of the BSD 2 Clause License and
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* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
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* was not distributed with this source code in the LICENSE file, you can
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* obtain it at www.aomedia.org/license/software. If the Alliance for Open
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* Media Patent License 1.0 was not distributed with this source code in the
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* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
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*/
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#include "av1/encoder/hash.h"
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#include "config/av1_rtcd.h"
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static void crc_calculator_process_data(CRC_CALCULATOR *p_crc_calculator,
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uint8_t *pData, uint32_t dataLength) {
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for (uint32_t i = 0; i < dataLength; i++) {
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const uint8_t index = (uint8_t)((p_crc_calculator->remainder >>
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(p_crc_calculator->bits - 8)) ^
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pData[i]);
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p_crc_calculator->remainder <<= 8;
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p_crc_calculator->remainder ^= p_crc_calculator->table[index];
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}
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}
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static void crc_calculator_reset(CRC_CALCULATOR *p_crc_calculator) {
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p_crc_calculator->remainder = 0;
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}
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static uint32_t crc_calculator_get_crc(CRC_CALCULATOR *p_crc_calculator) {
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return p_crc_calculator->remainder & p_crc_calculator->final_result_mask;
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}
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static void crc_calculator_init_table(CRC_CALCULATOR *p_crc_calculator) {
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const uint32_t high_bit = 1 << (p_crc_calculator->bits - 1);
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const uint32_t byte_high_bit = 1 << (8 - 1);
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for (uint32_t value = 0; value < 256; value++) {
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uint32_t remainder = 0;
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for (uint8_t mask = byte_high_bit; mask != 0; mask >>= 1) {
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if (value & mask) {
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remainder ^= high_bit;
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}
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if (remainder & high_bit) {
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remainder <<= 1;
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remainder ^= p_crc_calculator->trunc_poly;
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} else {
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remainder <<= 1;
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}
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}
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p_crc_calculator->table[value] = remainder;
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}
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}
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void av1_crc_calculator_init(CRC_CALCULATOR *p_crc_calculator, uint32_t bits,
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uint32_t truncPoly) {
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p_crc_calculator->remainder = 0;
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p_crc_calculator->bits = bits;
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p_crc_calculator->trunc_poly = truncPoly;
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p_crc_calculator->final_result_mask = (1 << bits) - 1;
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crc_calculator_init_table(p_crc_calculator);
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}
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uint32_t av1_get_crc_value(CRC_CALCULATOR *p_crc_calculator, uint8_t *p,
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int length) {
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crc_calculator_reset(p_crc_calculator);
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crc_calculator_process_data(p_crc_calculator, p, length);
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return crc_calculator_get_crc(p_crc_calculator);
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}
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/* CRC-32C (iSCSI) polynomial in reversed bit order. */
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#define POLY 0x82f63b78
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/* Construct table for software CRC-32C calculation. */
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void av1_crc32c_calculator_init(CRC32C *p_crc32c) {
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uint32_t crc;
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for (int n = 0; n < 256; n++) {
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crc = n;
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crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
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crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
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crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
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crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
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crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
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crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
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crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
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crc = crc & 1 ? (crc >> 1) ^ POLY : crc >> 1;
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p_crc32c->table[0][n] = crc;
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}
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for (int n = 0; n < 256; n++) {
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crc = p_crc32c->table[0][n];
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for (int k = 1; k < 8; k++) {
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crc = p_crc32c->table[0][crc & 0xff] ^ (crc >> 8);
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p_crc32c->table[k][n] = crc;
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}
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}
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}
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/* Table-driven software version as a fall-back. This is about 15 times slower
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than using the hardware instructions. This assumes little-endian integers,
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as is the case on Intel processors that the assembler code here is for. */
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uint32_t av1_get_crc32c_value_c(void *c, uint8_t *buf, size_t len) {
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const uint8_t *next = (const uint8_t *)(buf);
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uint64_t crc;
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CRC32C *p = (CRC32C *)c;
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crc = 0 ^ 0xffffffff;
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while (len && ((uintptr_t)next & 7) != 0) {
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crc = p->table[0][(crc ^ *next++) & 0xff] ^ (crc >> 8);
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len--;
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}
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while (len >= 8) {
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crc ^= *(uint64_t *)next;
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crc = p->table[7][crc & 0xff] ^ p->table[6][(crc >> 8) & 0xff] ^
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p->table[5][(crc >> 16) & 0xff] ^ p->table[4][(crc >> 24) & 0xff] ^
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p->table[3][(crc >> 32) & 0xff] ^ p->table[2][(crc >> 40) & 0xff] ^
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p->table[1][(crc >> 48) & 0xff] ^ p->table[0][crc >> 56];
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next += 8;
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len -= 8;
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}
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while (len) {
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crc = p->table[0][(crc ^ *next++) & 0xff] ^ (crc >> 8);
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len--;
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}
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return (uint32_t)crc ^ 0xffffffff;
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}
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