PeerStreamer

/*

 * AC-3 DSP utils

 * Copyright (c) 2011 Justin Ruggles

 *

 * 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

 */

#include "avcodec.h"

#include "ac3dsp.h"

static void ac3_exponent_min_c(uint8_t *exp, int num_reuse_blocks, int nb_coefs)

{

    int blk, i;

    if (!num_reuse_blocks)

        return;

    for (i = 0; i < nb_coefs; i++) {

        uint8_t min_exp = *exp;

        uint8_t *exp1 = exp + 256;

        for (blk = 0; blk < num_reuse_blocks; blk++) {

            uint8_t next_exp = *exp1;

            if (next_exp < min_exp)

                min_exp = next_exp;

            exp1 += 256;

        }

        *exp++ = min_exp;

    }

}

static int ac3_max_msb_abs_int16_c(const int16_t *src, int len)

{

    int i, v = 0;

    for (i = 0; i < len; i++)

        v |= abs(src[i]);

    return v;

}

static void ac3_lshift_int16_c(int16_t *src, unsigned int len,

                               unsigned int shift)

{

    uint32_t *src32 = (uint32_t *)src;

    const uint32_t mask = ~(((1 << shift) - 1) << 16);

    int i;

    len >>= 1;

    for (i = 0; i < len; i += 8) {

        src32[i  ] = (src32[i  ] << shift) & mask;

        src32[i+1] = (src32[i+1] << shift) & mask;

        src32[i+2] = (src32[i+2] << shift) & mask;

        src32[i+3] = (src32[i+3] << shift) & mask;

        src32[i+4] = (src32[i+4] << shift) & mask;

        src32[i+5] = (src32[i+5] << shift) & mask;

        src32[i+6] = (src32[i+6] << shift) & mask;

        src32[i+7] = (src32[i+7] << shift) & mask;

    }

}

static void ac3_rshift_int32_c(int32_t *src, unsigned int len,

                               unsigned int shift)

{

    do {

        *src++ >>= shift;

        *src++ >>= shift;

        *src++ >>= shift;

        *src++ >>= shift;

        *src++ >>= shift;

        *src++ >>= shift;

        *src++ >>= shift;

        *src++ >>= shift;

        len -= 8;

    } while (len > 0);

}

av_cold void ff_ac3dsp_init(AC3DSPContext *c)

{

    c->ac3_exponent_min = ac3_exponent_min_c;

    c->ac3_max_msb_abs_int16 = ac3_max_msb_abs_int16_c;

    c->ac3_lshift_int16 = ac3_lshift_int16_c;

    c->ac3_rshift_int32 = ac3_rshift_int32_c;

    if (HAVE_MMX)

        ff_ac3dsp_init_x86(c);

}