/* * Copyright (c) 2025 Shreesh Adiga <16567adigashreesh@gmail.com> * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #ifndef AVUTIL_X86_CRC_H #define AVUTIL_X86_CRC_H #include "config.h" #include "libavutil/attributes.h" #include "libavutil/attributes_internal.h" #include "libavutil/avassert.h" #include "libavutil/cpu.h" #include "libavutil/crc.h" #include "libavutil/intreadwrite.h" #include "libavutil/reverse.h" #include "libavutil/x86/cpu.h" #if HAVE_CLMUL_EXTERNAL FF_VISIBILITY_PUSH_HIDDEN uint32_t ff_crc_clmul(const AVCRC *ctx, uint32_t crc, const uint8_t *buffer, size_t length); uint32_t ff_crc_le_clmul(const AVCRC *ctx, uint32_t crc, const uint8_t *buffer, size_t length); FF_VISIBILITY_POP_HIDDEN enum { CRC_C = 0, CLMUL_BE, CLMUL_LE, }; static const AVCRC crc_table_clmul[AV_CRC_MAX][17] = { [AV_CRC_8_ATM] = { CLMUL_BE, 0x32000000, 0x0, 0xbc000000, 0x0, 0xc4000000, 0x0, 0x94000000, 0x0, 0x62000000, 0x0, 0x79000000, 0x0, 0x07156a16, 0x1, 0x07000000, 0x1, }, [AV_CRC_8_EBU] = { CLMUL_BE, 0xb5000000, 0x0, 0xf3000000, 0x0, 0xfc000000, 0x0, 0x0d000000, 0x0, 0x6a000000, 0x0, 0x65000000, 0x0, 0x1c4b8192, 0x1, 0x1d000000, 0x1, }, [AV_CRC_16_ANSI] = { CLMUL_BE, 0xf9e30000, 0x0, 0x807d0000, 0x0, 0xf9130000, 0x0, 0xff830000, 0x0, 0x807b0000, 0x0, 0x86630000, 0x0, 0xfffbffe7, 0x1, 0x80050000, 0x1, }, [AV_CRC_16_CCITT] = { CLMUL_BE, 0x60190000, 0x0, 0x59b00000, 0x0, 0xd5f60000, 0x0, 0x45630000, 0x0, 0xaa510000, 0x0, 0xeb230000, 0x0, 0x11303471, 0x1, 0x10210000, 0x1, }, [AV_CRC_24_IEEE] = { CLMUL_BE, 0x1f428700, 0x0, 0x467d2400, 0x0, 0x2c8c9d00, 0x0, 0x64e4d700, 0x0, 0xd9fe8c00, 0x0, 0xfd7e0c00, 0x0, 0xf845fe24, 0x1, 0x864cfb00, 0x1, }, [AV_CRC_32_IEEE] = { CLMUL_BE, 0x8833794c, 0x0, 0xe6228b11, 0x0, 0xc5b9cd4c, 0x0, 0xe8a45605, 0x0, 0x490d678d, 0x0, 0xf200aa66, 0x0, 0x04d101df, 0x1, 0x04c11db7, 0x1, }, [AV_CRC_32_IEEE_LE] = { CLMUL_LE, 0xc6e41596, 0x1, 0x54442bd4, 0x1, 0xccaa009e, 0x0, 0x751997d0, 0x1, 0xccaa009e, 0x0, 0x63cd6124, 0x1, 0xf7011640, 0x1, 0xdb710641, 0x1, }, [AV_CRC_16_ANSI_LE] = { CLMUL_LE, 0x0000bffa, 0x0, 0x1b0c2, 0x0, 0x00018cc2, 0x0, 0x1d0c2, 0x0, 0x00018cc2, 0x0, 0x1bc02, 0x0, 0xcfffbffe, 0x1, 0x14003, 0x0, }, }; static uint64_t reverse(uint64_t p, unsigned int deg) { uint64_t ret = 0; int i; for (i = 0; i < (deg / 8); i += 1) { ret = (ret << 8) | (ff_reverse[p & 0xff]); p >>= 8; } int rem = (deg + 1) - 8 * i; ret = (ret << rem) | (ff_reverse[p & 0xff] >> (8 - rem)); return ret; } static uint64_t xnmodp(unsigned n, uint64_t poly, unsigned deg, uint64_t *div, int bitreverse) { uint64_t mod, mask, high; if (n < deg) { *div = 0; return poly; } mask = ((uint64_t)1 << deg) - 1; poly &= mask; mod = poly; *div = 1; deg--; while (--n > deg) { high = (mod >> deg) & 1; *div = (*div << 1) | high; mod <<= 1; if (high) mod ^= poly; } uint64_t ret = mod & mask; if (bitreverse) { *div = reverse(*div, deg) << 1; return reverse(ret, deg) << 1; } return ret; } static inline void crc_init_x86(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size) { uint64_t poly_; if (le) { // convert the reversed representation to regular form poly = reverse(poly, bits) >> 1; } // convert to 32 degree polynomial poly_ = ((uint64_t)poly) << (32 - bits); uint64_t div; uint8_t *dst = (uint8_t*)(ctx + 1); if (le) { ctx[0] = CLMUL_LE; AV_WN64(dst, xnmodp(4 * 128 - 32, poly_, 32, &div, le)); AV_WN64(dst + 8, xnmodp(4 * 128 + 32, poly_, 32, &div, le)); uint64_t tmp = xnmodp(128 - 32, poly_, 32, &div, le); AV_WN64(dst + 16, tmp); AV_WN64(dst + 24, xnmodp(128 + 32, poly_, 32, &div, le)); AV_WN64(dst + 32, tmp); AV_WN64(dst + 40, xnmodp(64, poly_, 32, &div, le)); AV_WN64(dst + 48, div); AV_WN64(dst + 56, reverse(poly_ | (1ULL << 32), 32)); } else { ctx[0] = CLMUL_BE; AV_WN64(dst, xnmodp(4 * 128 + 64, poly_, 32, &div, le)); AV_WN64(dst + 8, xnmodp(4 * 128, poly_, 32, &div, le)); AV_WN64(dst + 16, xnmodp(128 + 64, poly_, 32, &div, le)); AV_WN64(dst + 24, xnmodp(128, poly_, 32, &div, le)); AV_WN64(dst + 32, xnmodp(64, poly_, 32, &div, le)); AV_WN64(dst + 48, div); AV_WN64(dst + 40, xnmodp(96, poly_, 32, &div, le)); AV_WN64(dst + 56, poly_ | (1ULL << 32)); } } #endif static inline const AVCRC *ff_crc_get_table_x86(AVCRCId crc_id) { #if HAVE_CLMUL_EXTERNAL int cpu_flags = av_get_cpu_flags(); if (EXTERNAL_CLMUL(cpu_flags)) { return crc_table_clmul[crc_id]; } #endif return NULL; } static inline av_cold int ff_crc_init_x86(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size) { #if HAVE_CLMUL_EXTERNAL int cpu_flags = av_get_cpu_flags(); if (EXTERNAL_CLMUL(cpu_flags)) { crc_init_x86(ctx, le, bits, poly, ctx_size); return 1; } #endif return 0; } static inline uint32_t ff_crc_x86(const AVCRC *ctx, uint32_t crc, const uint8_t *buffer, size_t length) { switch (ctx[0]) { #if HAVE_CLMUL_EXTERNAL case CLMUL_BE: return ff_crc_clmul(ctx, crc, buffer, length); case CLMUL_LE: return ff_crc_le_clmul(ctx, crc, buffer, length); #endif default: av_unreachable("x86 CRC only uses CLMUL_BE and CLMUL_LE"); } return 0; } #endif /* AVUTIL_X86_CRC_H */