diff options
Diffstat (limited to 'media/libaom/src/av1/encoder/hash.c')
| -rw-r--r-- | media/libaom/src/av1/encoder/hash.c | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/media/libaom/src/av1/encoder/hash.c b/media/libaom/src/av1/encoder/hash.c new file mode 100644 index 000000000..180115d9f --- /dev/null +++ b/media/libaom/src/av1/encoder/hash.c @@ -0,0 +1,125 @@ +/* + * 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 = + (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(void *crc_calculator, uint8_t *p, int length) { + CRC_CALCULATOR *p_crc_calculator = (CRC_CALCULATOR *)crc_calculator; + 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(CRC32C *p, uint8_t *buf, size_t len) { + const uint8_t *next = (const uint8_t *)(buf); + uint64_t crc; + + 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; +} |