/*
  * DCA ADPCM engine
  * Copyright (C) 2017 Daniil Cherednik
  *
  * 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 "dcaadpcm.h"
 #include "dcaenc.h"
 #include "dca_core.h"
 #include "mathops.h"
 
 typedef int32_t premultiplied_coeffs[10];
 
 //assume we have DCA_ADPCM_COEFFS values before x
 static inline int64_t calc_corr(const int32_t *x, int len, int j, int k)
 {
     int n;
     int64_t s = 0;
     for (n = 0; n < len; n++)
         s += MUL64(x[n-j], x[n-k]);
     return s;
 }
 
 static inline int64_t apply_filter(const int16_t a[DCA_ADPCM_COEFFS], const int64_t corr[15], const int32_t aa[10])
 {
     int64_t err = 0;
     int64_t tmp = 0;
 
     err = corr[0];
 
     tmp += MUL64(a[0], corr[1]);
     tmp += MUL64(a[1], corr[2]);
     tmp += MUL64(a[2], corr[3]);
     tmp += MUL64(a[3], corr[4]);
 
     tmp = norm__(tmp, 13);
     tmp += tmp;
 
     err -= tmp;
     tmp = 0;
 
     tmp += MUL64(corr[5], aa[0]);
     tmp += MUL64(corr[6], aa[1]);
     tmp += MUL64(corr[7], aa[2]);
     tmp += MUL64(corr[8], aa[3]);
 
     tmp += MUL64(corr[9], aa[4]);
     tmp += MUL64(corr[10], aa[5]);
     tmp += MUL64(corr[11], aa[6]);
 
     tmp += MUL64(corr[12], aa[7]);
     tmp += MUL64(corr[13], aa[8]);
 
     tmp += MUL64(corr[14], aa[9]);
 
     tmp = norm__(tmp, 26);
 
     err += tmp;
 
     return llabs(err);
 }
 
 static int64_t find_best_filter(const DCAADPCMEncContext *s, const int32_t *in, int len)
 {
     const premultiplied_coeffs *precalc_data = s->private_data;
     int i, j, k = 0;

     int vq = -1;

     int64_t err;
     int64_t min_err = 1ll << 62;
     int64_t corr[15];
 
     for (i = 0; i <= DCA_ADPCM_COEFFS; i++)
         for (j = i; j <= DCA_ADPCM_COEFFS; j++)
             corr[k++] = calc_corr(in+4, len, i, j);
 
     for (i = 0; i < DCA_ADPCM_VQCODEBOOK_SZ; i++) {
         err = apply_filter(ff_dca_adpcm_vb[i], corr, *precalc_data);
         if (err < min_err) {
             min_err = err;
             vq = i;
         }
         precalc_data++;
     }
 
     return vq;
 }
 
 static inline int64_t calc_prediction_gain(int pred_vq, const int32_t *in, int32_t *out, int len)
 {
     int i;
     int32_t error;
 
     int64_t signal_energy = 0;
     int64_t error_energy = 0;
 
     for (i = 0; i < len; i++) {
         error = in[DCA_ADPCM_COEFFS + i] - ff_dcaadpcm_predict(pred_vq, in + i);
         out[i] = error;
         signal_energy += MUL64(in[DCA_ADPCM_COEFFS + i], in[DCA_ADPCM_COEFFS + i]);
         error_energy += MUL64(error, error);
     }
 
     if (!error_energy)
         return -1;
 
     return signal_energy / error_energy;
 }
 
 int ff_dcaadpcm_subband_analysis(const DCAADPCMEncContext *s, const int32_t *in, int len, int *diff)
 {
     int pred_vq, i;
     int32_t input_buffer[16 + DCA_ADPCM_COEFFS];
     int32_t input_buffer2[16 + DCA_ADPCM_COEFFS];
 
     int32_t max = 0;
     int shift_bits;
     uint64_t pg = 0;
 
     for (i = 0; i < len + DCA_ADPCM_COEFFS; i++)
         max |= FFABS(in[i]);
 
     // normalize input to simplify apply_filter
     shift_bits = av_log2(max) - 11;
 
     for (i = 0; i < len + DCA_ADPCM_COEFFS; i++) {
         input_buffer[i] = norm__(in[i], 7);
         input_buffer2[i] = norm__(in[i], shift_bits);
     }
 
     pred_vq = find_best_filter(s, input_buffer2, len);
 
     if (pred_vq < 0)
         return -1;
 
     pg = calc_prediction_gain(pred_vq, input_buffer, diff, len);
 
     // Greater than 10db (10*log(10)) prediction gain to use ADPCM.
     // TODO: Tune it.
     if (pg < 10)
         return -1;
 
     for (i = 0; i < len; i++)
         diff[i] <<= 7;
 
     return pred_vq;
 }
 
 static void precalc(premultiplied_coeffs *data)
 {
     int i, j, k;
 
     for (i = 0; i < DCA_ADPCM_VQCODEBOOK_SZ; i++) {
         int id = 0;
         int32_t t = 0;
         for (j = 0; j < DCA_ADPCM_COEFFS; j++) {
             for (k = j; k < DCA_ADPCM_COEFFS; k++) {
                 t = (int32_t)ff_dca_adpcm_vb[i][j] * (int32_t)ff_dca_adpcm_vb[i][k];
                 if (j != k)
                     t *= 2;
                 (*data)[id++] = t;
              }
         }
         data++;
     }
 }
 
 int ff_dcaadpcm_do_real(int pred_vq_index,
                         softfloat quant, int32_t scale_factor, int32_t step_size,
                         const int32_t *prev_hist, const int32_t *in, int32_t *next_hist, int32_t *out,
                         int len, int32_t peak)
 {
     int i;
     int64_t delta;
     int32_t dequant_delta;
     int32_t work_bufer[16 + DCA_ADPCM_COEFFS];
 
     memcpy(work_bufer, prev_hist, sizeof(int32_t) * DCA_ADPCM_COEFFS);
 
     for (i = 0; i < len; i++) {
         work_bufer[DCA_ADPCM_COEFFS + i] = ff_dcaadpcm_predict(pred_vq_index, &work_bufer[i]);
 
         delta = (int64_t)in[i] - ((int64_t)work_bufer[DCA_ADPCM_COEFFS + i] << 7);
 
         out[i] = quantize_value(av_clip64(delta, -peak, peak), quant);
 
         ff_dca_core_dequantize(&dequant_delta, &out[i], step_size, scale_factor, 0, 1);
 
         work_bufer[DCA_ADPCM_COEFFS+i] += dequant_delta;
     }
 
     memcpy(next_hist, &work_bufer[len], sizeof(int32_t) * DCA_ADPCM_COEFFS);
 
     return 0;
 }
 
 av_cold int ff_dcaadpcm_init(DCAADPCMEncContext *s)
 {
     if (!s)
         return -1;
 
     s->private_data = av_malloc(sizeof(premultiplied_coeffs) * DCA_ADPCM_VQCODEBOOK_SZ);

     if (!s->private_data)
         return AVERROR(ENOMEM);
 

     precalc(s->private_data);
     return 0;
 }
 
 av_cold void ff_dcaadpcm_free(DCAADPCMEncContext *s)
 {
     if (!s)
         return;
 
     av_freep(&s->private_data);
 }