/*

 * common functions for the ATRAC family of decoders

 *

 * Copyright (c) 2006-2013 Maxim Poliakovski

 * Copyright (c) 2006-2008 Benjamin Larsson

 *

 * 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

 */

/**

 * @file

 */

#include <math.h>

#include <string.h>

#include "libavutil/attributes.h"

#include "libavutil/thread.h"

#include "atrac.h"

float ff_atrac_sf_table[64];

static float qmf_window[48];

static const float qmf_48tap_half[24] = {

   -0.00001461907, -0.00009205479,-0.000056157569,0.00030117269,

    0.0002422519,  -0.00085293897,-0.0005205574,  0.0020340169,

    0.00078333891, -0.0042153862, -0.00075614988, 0.0078402944,

   -0.000061169922,-0.01344162,    0.0024626821,  0.021736089,

   -0.007801671,   -0.034090221,   0.01880949,    0.054326009,

   -0.043596379,   -0.099384367,   0.13207909,    0.46424159

};

static av_cold void atrac_generate_tables(void)

{

    /* Generate scale factors */

    for (int i = 0; i < 64; i++)

        ff_atrac_sf_table[i] = pow(2.0, (i - 15) / 3.0);

    /* Generate the QMF window. */

    for (int i = 0; i < 24; i++) {

        float s = qmf_48tap_half[i] * 2.0;

        qmf_window[i] = qmf_window[47 - i] = s;

    }

}

av_cold void ff_atrac_generate_tables(void)

{

    static AVOnce init_static_once = AV_ONCE_INIT;

    ff_thread_once(&init_static_once, atrac_generate_tables);

}

av_cold void ff_atrac_init_gain_compensation(AtracGCContext *gctx, int id2exp_offset,

                                             int loc_scale)

{

    int i;

    gctx->loc_scale     = loc_scale;

    gctx->loc_size      = 1 << loc_scale;

    gctx->id2exp_offset = id2exp_offset;

    /* Generate gain level table. */

    for (i = 0; i < 16; i++)

        gctx->gain_tab1[i] = powf(2.0, id2exp_offset - i);

    /* Generate gain interpolation table. */

    for (i = -15; i < 16; i++)

        gctx->gain_tab2[i + 15] = powf(2.0, -1.0f / gctx->loc_size * i);

}

void ff_atrac_gain_compensation(AtracGCContext *gctx, float *in, float *prev,

                                AtracGainInfo *gc_now, AtracGainInfo *gc_next,

                                int num_samples, float *out)

{

    float lev, gc_scale, gain_inc;

    int i, pos, lastpos;

    gc_scale = gc_next->num_points ? gctx->gain_tab1[gc_next->lev_code[0]]

                                   : 1.0f;

    if (!gc_now->num_points) {

        for (pos = 0; pos < num_samples; pos++)

            out[pos] = in[pos] * gc_scale + prev[pos];

    } else {

        pos = 0;

        for (i = 0; i < gc_now->num_points; i++) {

            lastpos = gc_now->loc_code[i] << gctx->loc_scale;

            lev = gctx->gain_tab1[gc_now->lev_code[i]];

            gain_inc = gctx->gain_tab2[(i + 1 < gc_now->num_points ? gc_now->lev_code[i + 1]

                                                                   : gctx->id2exp_offset) -

                                       gc_now->lev_code[i] + 15];

            /* apply constant gain level and overlap */

            for (; pos < lastpos; pos++)

                out[pos] = (in[pos] * gc_scale + prev[pos]) * lev;

            /* interpolate between two different gain levels */

            for (; pos < lastpos + gctx->loc_size; pos++) {

                out[pos] = (in[pos] * gc_scale + prev[pos]) * lev;

                lev *= gain_inc;

            }

        }

        for (; pos < num_samples; pos++)

            out[pos] = in[pos] * gc_scale + prev[pos];

    }

    /* copy the overlapping part into the delay buffer */

    memcpy(prev, &in[num_samples], num_samples * sizeof(float));

}

void ff_atrac_iqmf(float *inlo, float *inhi, unsigned int nIn, float *pOut,

                   float *delayBuf, float *temp)

{

    int   i, j;

    float   *p1, *p3;

    memcpy(temp, delayBuf, 46*sizeof(float));

    p3 = temp + 46;

    /* loop1 */

    for(i=0; i<nIn; i+=2){

        p3[2*i+0] = inlo[i  ] + inhi[i  ];

        p3[2*i+1] = inlo[i  ] - inhi[i  ];

        p3[2*i+2] = inlo[i+1] + inhi[i+1];

        p3[2*i+3] = inlo[i+1] - inhi[i+1];

    }

    /* loop2 */

    p1 = temp;

    for (j = nIn; j != 0; j--) {

        float s1 = 0.0;

        float s2 = 0.0;

        for (i = 0; i < 48; i += 2) {

            s1 += p1[i] * qmf_window[i];

            s2 += p1[i+1] * qmf_window[i+1];

        }

        pOut[0] = s2;

        pOut[1] = s1;

        p1 += 2;

        pOut += 2;

    }

    /* Update the delay buffer. */

    memcpy(delayBuf, temp + nIn*2, 46*sizeof(float));

}