mirror of https://git.ffmpeg.org/ffmpeg.git
243 lines
7.3 KiB
C
243 lines
7.3 KiB
C
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/*
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* Copyright (C) 2016 Open Broadcast Systems Ltd.
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* Author 2016 Rostislav Pehlivanov <rpehlivanov@obe.tv>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "dirac_vlc.h"
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#define LUT_SIZE (1 << LUT_BITS)
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#define RSIZE_BITS (CHAR_BIT*sizeof(residual))
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#define CONVERT_TO_RESIDUE(a, b) \
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(((residual)(a)) << (RSIZE_BITS - (b)))
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#define INIT_RESIDUE(N, I, B) \
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residual N = B ? CONVERT_TO_RESIDUE(I, B) : 0; \
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av_unused int32_t N ## _bits = B
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int ff_dirac_golomb_read_32bit(DiracGolombLUT *lut_ctx, const uint8_t *buf,
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int bytes, uint8_t *_dst, int coeffs)
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{
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int i, b, c_idx = 0;
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int32_t *dst = (int32_t *)_dst;
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DiracGolombLUT *future[4], *l = &lut_ctx[2*LUT_SIZE + buf[0]];
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INIT_RESIDUE(res, 0, 0);
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#define APPEND_RESIDUE(N, M) \
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N |= M >> (N ## _bits); \
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N ## _bits += (M ## _bits)
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for (b = 1; b <= bytes; b++) {
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future[0] = &lut_ctx[buf[b]];
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future[1] = future[0] + 1*LUT_SIZE;
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future[2] = future[0] + 2*LUT_SIZE;
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future[3] = future[0] + 3*LUT_SIZE;
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if ((c_idx + 1) > coeffs)
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return c_idx;
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/* res_bits is a hint for better branch prediction */
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if (res_bits && l->sign) {
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int32_t coeff = 1;
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APPEND_RESIDUE(res, l->preamble);
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for (i = 0; i < (res_bits >> 1) - 1; i++) {
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coeff <<= 1;
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coeff |= (res >> (RSIZE_BITS - 2*i - 2)) & 1;
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}
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dst[c_idx++] = l->sign * (coeff - 1);
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res_bits = res = 0;
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}
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memcpy(&dst[c_idx], l->ready, LUT_BITS*sizeof(int32_t));
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c_idx += l->ready_num;
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APPEND_RESIDUE(res, l->leftover);
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l = future[l->need_s ? 3 : !res_bits ? 2 : res_bits & 1];
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}
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return c_idx;
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}
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int ff_dirac_golomb_read_16bit(DiracGolombLUT *lut_ctx, const uint8_t *buf,
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int bytes, uint8_t *_dst, int coeffs)
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{
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int i, b, c_idx = 0;
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int16_t *dst = (int16_t *)_dst;
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DiracGolombLUT *future[4], *l = &lut_ctx[2*LUT_SIZE + buf[0]];
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INIT_RESIDUE(res, 0, 0);
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#define APPEND_RESIDUE(N, M) \
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N |= M >> (N ## _bits); \
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N ## _bits += (M ## _bits)
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for (b = 1; b <= bytes; b++) {
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future[0] = &lut_ctx[buf[b]];
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future[1] = future[0] + 1*LUT_SIZE;
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future[2] = future[0] + 2*LUT_SIZE;
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future[3] = future[0] + 3*LUT_SIZE;
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if ((c_idx + 1) > coeffs)
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return c_idx;
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if (res_bits && l->sign) {
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int32_t coeff = 1;
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APPEND_RESIDUE(res, l->preamble);
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for (i = 0; i < (res_bits >> 1) - 1; i++) {
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coeff <<= 1;
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coeff |= (res >> (RSIZE_BITS - 2*i - 2)) & 1;
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}
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dst[c_idx++] = l->sign * (coeff - 1);
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res_bits = res = 0;
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}
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for (i = 0; i < LUT_BITS; i++)
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dst[c_idx + i] = l->ready[i];
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c_idx += l->ready_num;
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APPEND_RESIDUE(res, l->leftover);
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l = future[l->need_s ? 3 : !res_bits ? 2 : res_bits & 1];
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}
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return c_idx;
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}
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/* Searches for golomb codes in a residue */
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static inline void search_for_golomb(DiracGolombLUT *l, residual r, int bits)
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{
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int r_count = RSIZE_BITS - 1;
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int bits_start, bits_tot = bits, need_sign = 0;
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#define READ_BIT(N) (((N) >> (N ## _count--)) & 1)
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while (1) {
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int32_t coef = 1;
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bits_start = (RSIZE_BITS - 1) - r_count;
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while (1) {
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if (!bits--)
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goto leftover;
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if (READ_BIT(r))
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break;
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coef <<= 1;
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if (!bits--)
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goto leftover;
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coef |= READ_BIT(r);
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}
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l->ready[l->ready_num] = coef - 1;
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if (l->ready[l->ready_num]) {
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if (!bits--) {
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need_sign = 1;
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goto leftover;
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}
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l->ready[l->ready_num] *= READ_BIT(r) ? -1 : +1;
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}
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l->ready_num++;
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if (!bits)
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return;
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}
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leftover:
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l->leftover = r << bits_start;
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l->leftover_bits = bits_tot - bits_start;
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l->need_s = need_sign;
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}
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/* Parity LUTs - even and odd bit end positions */
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static void generate_parity_lut(DiracGolombLUT *lut, int even)
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{
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for (int idx = 0; idx < LUT_SIZE; idx++) {
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DiracGolombLUT *l = &lut[idx];
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int symbol_end_loc = -1;
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uint32_t code;
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INIT_RESIDUE(res, idx, LUT_BITS);
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for (int i = 0; i < LUT_BITS; i++) {
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const int cond = even ? (i & 1) : !(i & 1);
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if (((res >> (RSIZE_BITS - i - 1)) & 1) && cond) {
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symbol_end_loc = i + 2;
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break;
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}
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}
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if (symbol_end_loc < 0 || symbol_end_loc > LUT_BITS) {
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l->preamble = 0;
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l->preamble_bits = 0;
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l->leftover_bits = LUT_BITS;
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l->leftover = CONVERT_TO_RESIDUE(idx, l->leftover_bits);
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if (even)
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l->need_s = idx & 1;
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continue;
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}
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/* Gets bits 0 through to (symbol_end_loc - 1) inclusive */
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code = idx >> ((LUT_BITS - 1) - (symbol_end_loc - 1));
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code &= ((1 << LUT_BITS) - 1) >> (LUT_BITS - symbol_end_loc);
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l->preamble_bits = symbol_end_loc;
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l->preamble = CONVERT_TO_RESIDUE(code, l->preamble_bits);
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l->sign = ((l->preamble >> (RSIZE_BITS - l->preamble_bits)) & 1) ? -1 : +1;
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search_for_golomb(l, res << symbol_end_loc, LUT_BITS - symbol_end_loc);
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}
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}
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/* Reset (off == 0) and needs-one-more-bit (off == 1) LUTs */
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static void generate_offset_lut(DiracGolombLUT *lut, int off)
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{
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for (int idx = 0; idx < LUT_SIZE; idx++) {
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DiracGolombLUT *l = &lut[idx];
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INIT_RESIDUE(res, idx, LUT_BITS);
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l->preamble = CONVERT_TO_RESIDUE(res >> (RSIZE_BITS - off), off);
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l->preamble_bits = off;
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l->sign = ((l->preamble >> (RSIZE_BITS - l->preamble_bits)) & 1) ? -1 : +1;
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search_for_golomb(l, res << off, LUT_BITS - off);
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}
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}
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av_cold int ff_dirac_golomb_reader_init(DiracGolombLUT **lut_ctx)
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{
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DiracGolombLUT *lut;
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if (!(lut = av_calloc(4*LUT_SIZE, sizeof(DiracGolombLUT))))
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return AVERROR(ENOMEM);
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generate_parity_lut(&lut[0*LUT_SIZE], 0);
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generate_parity_lut(&lut[1*LUT_SIZE], 1);
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generate_offset_lut(&lut[2*LUT_SIZE], 0);
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generate_offset_lut(&lut[3*LUT_SIZE], 1);
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*lut_ctx = lut;
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return 0;
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}
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av_cold void ff_dirac_golomb_reader_end(DiracGolombLUT **lut_ctx)
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{
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av_freep(lut_ctx);
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}
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