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ffmpeg / libavcodec / ac3dsp.c @ cc4d3dd3

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/*
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 * AC-3 DSP utils
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 * Copyright (c) 2011 Justin Ruggles
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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 "avcodec.h"
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#include "ac3dsp.h"
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static void ac3_exponent_min_c(uint8_t *exp, int num_reuse_blocks, int nb_coefs)
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{
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    int blk, i;
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    if (!num_reuse_blocks)
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        return;
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    for (i = 0; i < nb_coefs; i++) {
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        uint8_t min_exp = *exp;
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        uint8_t *exp1 = exp + 256;
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        for (blk = 0; blk < num_reuse_blocks; blk++) {
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            uint8_t next_exp = *exp1;
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            if (next_exp < min_exp)
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                min_exp = next_exp;
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            exp1 += 256;
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        }
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        *exp++ = min_exp;
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    }
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}
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static int ac3_max_msb_abs_int16_c(const int16_t *src, int len)
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{
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    int i, v = 0;
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    for (i = 0; i < len; i++)
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        v |= abs(src[i]);
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    return v;
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}
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static void ac3_lshift_int16_c(int16_t *src, int len, unsigned int shift)
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{
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    int i;
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    if (shift > 0) {
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        for (i = 0; i < len; i++)
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            src[i] <<= shift;
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    }
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}
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static void ac3_shift_int32_c(int32_t *src, int len, int shift)
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{
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    int i;
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    if (shift > 0) {
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        for (i = 0; i < len; i++)
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            src[i] <<= shift;
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    } else if (shift < 0) {
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        shift = -shift;
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        for (i = 0; i < len; i++)
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            src[i] >>= shift;
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    }
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}
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av_cold void ff_ac3dsp_init(AC3DSPContext *c)
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{
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    c->ac3_exponent_min = ac3_exponent_min_c;
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    c->ac3_max_msb_abs_int16 = ac3_max_msb_abs_int16_c;
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    c->ac3_lshift_int16 = ac3_lshift_int16_c;
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    c->ac3_shift_int32  = ac3_shift_int32_c;
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    if (HAVE_MMX)
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        ff_ac3dsp_init_x86(c);
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}