/*
  * TwinVQ decoder
  * Copyright (c) 2009 Vitor Sessak
  *
  * 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 <math.h>
 #include <stdint.h>
 

 #include "libavutil/channel_layout.h"

 #include "libavutil/float_dsp.h"

 #include "avcodec.h"

 #include "fft.h"

 #include "internal.h"

 #include "lsp.h"

 #include "sinewin.h"

 #include "twinvq.h"

 
 /**
  * Evaluate a single LPC amplitude spectrum envelope coefficient from the line
  * spectrum pairs.
  *

  * @param lsp a vector of the cosine of the LSP values

  * @param cos_val cos(PI*i/N) where i is the index of the LPC amplitude
  * @param order the order of the LSP (and the size of the *lsp buffer). Must
  *        be a multiple of four.
  * @return the LPC value
  *

  * @todo reuse code from Vorbis decoder: vorbis_floor0_decode

  */
 static float eval_lpc_spectrum(const float *lsp, float cos_val, int order)
 {
     int j;

     float p         = 0.5f;
     float q         = 0.5f;
     float two_cos_w = 2.0f * cos_val;

     for (j = 0; j + 1 < order; j += 2 * 2) {

         // Unroll the loop once since order is a multiple of four

         q *= lsp[j]     - two_cos_w;
         p *= lsp[j + 1] - two_cos_w;

         q *= lsp[j + 2] - two_cos_w;
         p *= lsp[j + 3] - two_cos_w;

     }
 
     p *= p * (2.0f - two_cos_w);
     q *= q * (2.0f + two_cos_w);
 
     return 0.5 / (p + q);
 }
 
 /**

  * Evaluate the LPC amplitude spectrum envelope from the line spectrum pairs.

  */

 static void eval_lpcenv(TwinVQContext *tctx, const float *cos_vals, float *lpc)

 {
     int i;

     const TwinVQModeTab *mtab = tctx->mtab;

     int size_s = mtab->size / mtab->fmode[TWINVQ_FT_SHORT].sub;

     for (i = 0; i < size_s / 2; i++) {

         float cos_i = tctx->cos_tabs[0][i];

         lpc[i]              = eval_lpc_spectrum(cos_vals,  cos_i, mtab->n_lsp);
         lpc[size_s - i - 1] = eval_lpc_spectrum(cos_vals, -cos_i, mtab->n_lsp);

     }
 }
 
 static void interpolate(float *out, float v1, float v2, int size)
 {
     int i;

     float step = (v1 - v2) / (size + 1);

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

         v2    += step;

         out[i] = v2;
     }
 }
 
 static inline float get_cos(int idx, int part, const float *cos_tab, int size)
 {

     return part ? -cos_tab[size - idx - 1]
                 :  cos_tab[idx];

 }
 
 /**

  * Evaluate the LPC amplitude spectrum envelope from the line spectrum pairs.

  * Probably for speed reasons, the coefficients are evaluated as
  * siiiibiiiisiiiibiiiisiiiibiiiisiiiibiiiis ...
  * where s is an evaluated value, i is a value interpolated from the others
  * and b might be either calculated or interpolated, depending on an
  * unexplained condition.
  *
  * @param step the size of a block "siiiibiiii"

  * @param in the cosine of the LSP data
  * @param part is 0 for 0...PI (positive cosine values) and 1 for PI...2PI
  *        (negative cosine values)

  * @param size the size of the whole output
  */

 static inline void eval_lpcenv_or_interp(TwinVQContext *tctx,
                                          enum TwinVQFrameType ftype,

                                          float *out, const float *in,
                                          int size, int step, int part)
 {
     int i;

     const TwinVQModeTab *mtab = tctx->mtab;
     const float *cos_tab      = tctx->cos_tabs[ftype];

 
     // Fill the 's'

     for (i = 0; i < size; i += step)

         out[i] =
             eval_lpc_spectrum(in,
                               get_cos(i, part, cos_tab, size),
                               mtab->n_lsp);
 
     // Fill the 'iiiibiiii'

     for (i = step; i <= size - 2 * step; i += step) {
         if (out[i + step] + out[i - step] > 1.95 * out[i] ||
             out[i + step]                 >= out[i - step]) {
             interpolate(out + i - step + 1, out[i], out[i - step], step - 1);

         } else {

             out[i - step / 2] =

                 eval_lpc_spectrum(in,

                                   get_cos(i - step / 2, part, cos_tab, size),

                                   mtab->n_lsp);

             interpolate(out + i - step + 1, out[i - step / 2],
                         out[i - step], step / 2 - 1);
             interpolate(out + i - step / 2 + 1, out[i],
                         out[i - step / 2], step / 2 - 1);

         }
     }
 

     interpolate(out + size - 2 * step + 1, out[size - step],
                 out[size - 2 * step], step - 1);

 }
 

 static void eval_lpcenv_2parts(TwinVQContext *tctx, enum TwinVQFrameType ftype,

                                const float *buf, float *lpc,
                                int size, int step)
 {

     eval_lpcenv_or_interp(tctx, ftype, lpc, buf, size / 2, step, 0);
     eval_lpcenv_or_interp(tctx, ftype, lpc + size / 2, buf, size / 2,
                           2 * step, 1);

     interpolate(lpc + size / 2 - step + 1, lpc[size / 2],
                 lpc[size / 2 - step], step);

     twinvq_memset_float(lpc + size - 2 * step + 1, lpc[size - 2 * step],
                         2 * step - 1);

 }
 
 /**
  * Inverse quantization. Read CB coefficients for cb1 and cb2 from the
  * bitstream, sum the corresponding vectors and write the result to *out
  * after permutation.
  */

 static void dequant(TwinVQContext *tctx, const uint8_t *cb_bits, float *out,

                     enum TwinVQFrameType ftype,

                     const int16_t *cb0, const int16_t *cb1, int cb_len)
 {
     int pos = 0;
     int i, j;
 

     for (i = 0; i < tctx->n_div[ftype]; i++) {

         int tmp0, tmp1;
         int sign0 = 1;
         int sign1 = 1;
         const int16_t *tab0, *tab1;
         int length = tctx->length[ftype][i >= tctx->length_change[ftype]];
         int bitstream_second_part = (i >= tctx->bits_main_spec_change[ftype]);
 
         int bits = tctx->bits_main_spec[0][ftype][bitstream_second_part];

         tmp0 = *cb_bits++;

         if (bits == 7) {

             if (tmp0 & 0x40)

                 sign0 = -1;

             tmp0 &= 0x3F;

         }
 
         bits = tctx->bits_main_spec[1][ftype][bitstream_second_part];

         tmp1 = *cb_bits++;

         if (bits == 7) {

             if (tmp1 & 0x40)

                 sign1 = -1;

             tmp1 &= 0x3F;

         }
 

         tab0 = cb0 + tmp0 * cb_len;
         tab1 = cb1 + tmp1 * cb_len;

         for (j = 0; j < length; j++)

             out[tctx->permut[ftype][pos + j]] = sign0 * tab0[j] +
                                                 sign1 * tab1[j];

 
         pos += length;
     }
 }
 

 static void dec_gain(TwinVQContext *tctx,

                      enum TwinVQFrameType ftype, float *out)

 {

     const TwinVQModeTab   *mtab =  tctx->mtab;

     const TwinVQFrameData *bits = &tctx->bits[tctx->cur_frame];

     int i, j;

     int sub        = mtab->fmode[ftype].sub;

     float step     = TWINVQ_AMP_MAX     / ((1 << TWINVQ_GAIN_BITS)     - 1);
     float sub_step = TWINVQ_SUB_AMP_MAX / ((1 << TWINVQ_SUB_GAIN_BITS) - 1);

     if (ftype == TWINVQ_FT_LONG) {

         for (i = 0; i < tctx->avctx->channels; i++)

             out[i] = (1.0 / (1 << 13)) *

                      twinvq_mulawinv(step * 0.5 + step * bits->gain_bits[i],
                                      TWINVQ_AMP_MAX, TWINVQ_MULAW_MU);

     } else {

         for (i = 0; i < tctx->avctx->channels; i++) {

             float val = (1.0 / (1 << 23)) *

                         twinvq_mulawinv(step * 0.5 + step * bits->gain_bits[i],
                                         TWINVQ_AMP_MAX, TWINVQ_MULAW_MU);

 
             for (j = 0; j < sub; j++)
                 out[i * sub + j] =

                     val * twinvq_mulawinv(sub_step * 0.5 +
                                           sub_step * bits->sub_gain_bits[i * sub + j],
                                           TWINVQ_SUB_AMP_MAX, TWINVQ_MULAW_MU);

         }
     }
 }
 
 /**
  * Rearrange the LSP coefficients so that they have a minimum distance of
  * min_dist. This function does it exactly as described in section of 3.2.4
  * of the G.729 specification (but interestingly is different from what the
  * reference decoder actually does).
  */
 static void rearrange_lsp(int order, float *lsp, float min_dist)
 {
     int i;
     float min_dist2 = min_dist * 0.5;

     for (i = 1; i < order; i++)

         if (lsp[i] - lsp[i - 1] < min_dist) {
             float avg = (lsp[i] + lsp[i - 1]) * 0.5;

             lsp[i - 1] = avg - min_dist2;
             lsp[i]     = avg + min_dist2;

         }
 }
 

 static void decode_lsp(TwinVQContext *tctx, int lpc_idx1, uint8_t *lpc_idx2,

                        int lpc_hist_idx, float *lsp, float *hist)
 {

     const TwinVQModeTab *mtab = tctx->mtab;

     int i, j;
 

     const float *cb  = mtab->lspcodebook;
     const float *cb2 = cb  + (1 << mtab->lsp_bit1) * mtab->n_lsp;
     const float *cb3 = cb2 + (1 << mtab->lsp_bit2) * mtab->n_lsp;

 
     const int8_t funny_rounding[4] = {
         -2,
         mtab->lsp_split == 4 ? -2 : 1,
         mtab->lsp_split == 4 ? -2 : 1,
         0
     };
 

     j = 0;
     for (i = 0; i < mtab->lsp_split; i++) {

         int chunk_end = ((i + 1) * mtab->n_lsp + funny_rounding[i]) /
                         mtab->lsp_split;

         for (; j < chunk_end; j++)

             lsp[j] = cb[lpc_idx1     * mtab->n_lsp + j] +

                      cb2[lpc_idx2[i] * mtab->n_lsp + j];
     }
 
     rearrange_lsp(mtab->n_lsp, lsp, 0.0001);
 

     for (i = 0; i < mtab->n_lsp; i++) {

         float tmp1 = 1.0     - cb3[lpc_hist_idx * mtab->n_lsp + i];

         float tmp2 = hist[i] * cb3[lpc_hist_idx * mtab->n_lsp + i];

         hist[i] = lsp[i];
         lsp[i]  = lsp[i] * tmp1 + tmp2;
     }
 
     rearrange_lsp(mtab->n_lsp, lsp, 0.0001);
     rearrange_lsp(mtab->n_lsp, lsp, 0.000095);

     ff_sort_nearly_sorted_floats(lsp, mtab->n_lsp);

 }
 

 static void dec_lpc_spectrum_inv(TwinVQContext *tctx, float *lsp,
                                  enum TwinVQFrameType ftype, float *lpc)

 {
     int i;
     int size = tctx->mtab->size / tctx->mtab->fmode[ftype].sub;
 

     for (i = 0; i < tctx->mtab->n_lsp; i++)

         lsp[i] = 2 * cos(lsp[i]);

 
     switch (ftype) {

     case TWINVQ_FT_LONG:

         eval_lpcenv_2parts(tctx, ftype, lsp, lpc, size, 8);
         break;

     case TWINVQ_FT_MEDIUM:

         eval_lpcenv_2parts(tctx, ftype, lsp, lpc, size, 2);
         break;

     case TWINVQ_FT_SHORT:

         eval_lpcenv(tctx, lsp, lpc);
         break;
     }
 }
 

 static const uint8_t wtype_to_wsize[] = { 0, 0, 2, 2, 2, 1, 0, 1, 1 };
 

 static void imdct_and_window(TwinVQContext *tctx, enum TwinVQFrameType ftype,
                              int wtype, float *in, float *prev, int ch)

 {

     FFTContext *mdct = &tctx->mdct_ctx[ftype];
     const TwinVQModeTab *mtab = tctx->mtab;
     int bsize = mtab->size / mtab->fmode[ftype].sub;
     int size  = mtab->size;
     float *buf1 = tctx->tmp_buf;

     int j, first_wsize, wsize; // Window size
     float *out  = tctx->curr_frame + 2 * ch * mtab->size;

     float *out2 = out;
     float *prev_buf;
     int types_sizes[] = {

         mtab->size /  mtab->fmode[TWINVQ_FT_LONG].sub,
         mtab->size /  mtab->fmode[TWINVQ_FT_MEDIUM].sub,
         mtab->size / (mtab->fmode[TWINVQ_FT_SHORT].sub * 2),

     };
 

     wsize       = types_sizes[wtype_to_wsize[wtype]];

     first_wsize = wsize;

     prev_buf    = prev + (size - bsize) / 2;

     for (j = 0; j < mtab->fmode[ftype].sub; j++) {

         int sub_wtype = ftype == TWINVQ_FT_MEDIUM ? 8 : wtype;

 
         if (!j && wtype == 4)
             sub_wtype = 4;

         else if (j == mtab->fmode[ftype].sub - 1 && wtype == 7)

             sub_wtype = 7;
 
         wsize = types_sizes[wtype_to_wsize[sub_wtype]];
 

         mdct->imdct_half(mdct, buf1 + bsize * j, in + bsize * j);

         tctx->fdsp->vector_fmul_window(out2, prev_buf + (bsize - wsize) / 2,

                                       buf1 + bsize * j,
                                       ff_sine_windows[av_log2(wsize)],
                                       wsize / 2);

         out2 += wsize;
 

         memcpy(out2, buf1 + bsize * j + wsize / 2,
                (bsize - wsize / 2) * sizeof(float));

         out2 += ftype == TWINVQ_FT_MEDIUM ? (bsize - wsize) / 2 : bsize - wsize;

         prev_buf = buf1 + bsize * j + bsize / 2;

     }
 

     tctx->last_block_pos[ch] = (size + first_wsize) / 2;

 }
 

 static void imdct_output(TwinVQContext *tctx, enum TwinVQFrameType ftype,

                          int wtype, float **out, int offset)

 {

     const TwinVQModeTab *mtab = tctx->mtab;
     float *prev_buf           = tctx->prev_frame + tctx->last_block_pos[0];

     int size1, size2, i;

     float *out1, *out2;

     for (i = 0; i < tctx->avctx->channels; i++)

         imdct_and_window(tctx, ftype, wtype,

                          tctx->spectrum + i * mtab->size,
                          prev_buf + 2 * i * mtab->size,

                          i);
 

     if (!out)
         return;
 

     size2 = tctx->last_block_pos[0];
     size1 = mtab->size - size2;

     out1 = &out[0][0] + offset;
     memcpy(out1,         prev_buf,         size1 * sizeof(*out1));
     memcpy(out1 + size1, tctx->curr_frame, size2 * sizeof(*out1));

     if (tctx->avctx->channels == 2) {

         out2 = &out[1][0] + offset;
         memcpy(out2, &prev_buf[2 * mtab->size],
                size1 * sizeof(*out2));
         memcpy(out2 + size1, &tctx->curr_frame[2 * mtab->size],
                size2 * sizeof(*out2));

         tctx->fdsp->butterflies_float(out1, out2, mtab->size);

     }
 }
 

 static void read_and_decode_spectrum(TwinVQContext *tctx, float *out,
                                      enum TwinVQFrameType ftype)

 {

     const TwinVQModeTab *mtab = tctx->mtab;

     TwinVQFrameData *bits     = &tctx->bits[tctx->cur_frame];

     int channels              = tctx->avctx->channels;
     int sub        = mtab->fmode[ftype].sub;
     int block_size = mtab->size / sub;

     float gain[TWINVQ_CHANNELS_MAX * TWINVQ_SUBBLOCKS_MAX];
     float ppc_shape[TWINVQ_PPC_SHAPE_LEN_MAX * TWINVQ_CHANNELS_MAX * 4];

     int i, j;

     dequant(tctx, bits->main_coeffs, out, ftype,

             mtab->fmode[ftype].cb0, mtab->fmode[ftype].cb1,
             mtab->fmode[ftype].cb_len_read);
 

     dec_gain(tctx, ftype, gain);

     if (ftype == TWINVQ_FT_LONG) {

         int cb_len_p = (tctx->n_div[3] + mtab->ppc_shape_len * channels - 1) /
                        tctx->n_div[3];

         dequant(tctx, bits->ppc_coeffs, ppc_shape,
                 TWINVQ_FT_PPC, mtab->ppc_shape_cb,
                 mtab->ppc_shape_cb + cb_len_p * TWINVQ_PPC_SHAPE_CB_SIZE,
                 cb_len_p);

     }
 

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

         float *chunk = out + mtab->size * i;

         float lsp[TWINVQ_LSP_COEFS_MAX];

         for (j = 0; j < sub; j++) {

             tctx->dec_bark_env(tctx, bits->bark1[i][j],
                                bits->bark_use_hist[i][j], i,
                                tctx->tmp_buf, gain[sub * i + j], ftype);

             tctx->fdsp->vector_fmul(chunk + block_size * j,

                                    chunk + block_size * j,

                                    tctx->tmp_buf, block_size);

         }
 

         if (ftype == TWINVQ_FT_LONG)
             tctx->decode_ppc(tctx, bits->p_coef[i], bits->g_coef[i],
                              ppc_shape + i * mtab->ppc_shape_len, chunk);

         decode_lsp(tctx, bits->lpc_idx1[i], bits->lpc_idx2[i],
                    bits->lpc_hist_idx[i], lsp, tctx->lsp_hist[i]);

 
         dec_lpc_spectrum_inv(tctx, lsp, ftype, tctx->tmp_buf);
 

         for (j = 0; j < mtab->fmode[ftype].sub; j++) {

             tctx->fdsp->vector_fmul(chunk, chunk, tctx->tmp_buf, block_size);

             chunk += block_size;
         }
     }
 }
 

 const enum TwinVQFrameType ff_twinvq_wtype_to_ftype_table[] = {

     TWINVQ_FT_LONG,   TWINVQ_FT_LONG, TWINVQ_FT_SHORT, TWINVQ_FT_LONG,
     TWINVQ_FT_MEDIUM, TWINVQ_FT_LONG, TWINVQ_FT_LONG,  TWINVQ_FT_MEDIUM,
     TWINVQ_FT_MEDIUM

 };
 

 int ff_twinvq_decode_frame(AVCodecContext *avctx, void *data,
                            int *got_frame_ptr, AVPacket *avpkt)

 {

     AVFrame *frame     = data;

     const uint8_t *buf = avpkt->data;

     int buf_size       = avpkt->size;

     TwinVQContext *tctx = avctx->priv_data;
     const TwinVQModeTab *mtab = tctx->mtab;
     float **out = NULL;

     int ret;

     /* get output buffer */
     if (tctx->discarded_packets >= 2) {

         frame->nb_samples = mtab->size * tctx->frames_per_packet;

         if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)

             return ret;

         out = (float **)frame->extended_data;

     }
 

     if (buf_size < avctx->block_align) {
         av_log(avctx, AV_LOG_ERROR,
                "Frame too small (%d bytes). Truncated file?\n", buf_size);
         return AVERROR(EINVAL);
     }
 

     if ((ret = tctx->read_bitstream(avctx, tctx, buf, buf_size)) < 0)

         return ret;

     for (tctx->cur_frame = 0; tctx->cur_frame < tctx->frames_per_packet;
          tctx->cur_frame++) {
         read_and_decode_spectrum(tctx, tctx->spectrum,
                                  tctx->bits[tctx->cur_frame].ftype);

         imdct_output(tctx, tctx->bits[tctx->cur_frame].ftype,
                      tctx->bits[tctx->cur_frame].window_type, out,
                      tctx->cur_frame * mtab->size);

         FFSWAP(float *, tctx->curr_frame, tctx->prev_frame);
     }

     if (tctx->discarded_packets < 2) {
         tctx->discarded_packets++;
         *got_frame_ptr = 0;

         return buf_size;
     }
 

     *got_frame_ptr = 1;

     // VQF can deliver packets 1 byte greater than block align
     if (buf_size == avctx->block_align + 1)
         return buf_size;

     return avctx->block_align;

 }
 
 /**
  * Init IMDCT and windowing tables
  */

 static av_cold int init_mdct_win(TwinVQContext *tctx)

 {

     int i, j, ret;

     const TwinVQModeTab *mtab = tctx->mtab;

     int size_s = mtab->size / mtab->fmode[TWINVQ_FT_SHORT].sub;
     int size_m = mtab->size / mtab->fmode[TWINVQ_FT_MEDIUM].sub;

     int channels = tctx->avctx->channels;
     float norm = channels == 1 ? 2.0 : 1.0;

     for (i = 0; i < 3; i++) {

         int bsize = tctx->mtab->size / tctx->mtab->fmode[i].sub;

         if ((ret = ff_mdct_init(&tctx->mdct_ctx[i], av_log2(bsize) + 1, 1,

                                 -sqrt(norm / bsize) / (1 << 15))))

             return ret;

     }
 

     FF_ALLOC_ARRAY_OR_GOTO(tctx->avctx, tctx->tmp_buf,
                      mtab->size, sizeof(*tctx->tmp_buf), alloc_fail);

     FF_ALLOC_ARRAY_OR_GOTO(tctx->avctx, tctx->spectrum,
                      2 * mtab->size, channels * sizeof(*tctx->spectrum),

                      alloc_fail);

     FF_ALLOC_ARRAY_OR_GOTO(tctx->avctx, tctx->curr_frame,
                      2 * mtab->size, channels * sizeof(*tctx->curr_frame),

                      alloc_fail);

     FF_ALLOC_ARRAY_OR_GOTO(tctx->avctx, tctx->prev_frame,
                      2 * mtab->size, channels * sizeof(*tctx->prev_frame),

                      alloc_fail);

     for (i = 0; i < 3; i++) {

         int m       = 4 * mtab->size / mtab->fmode[i].sub;
         double freq = 2 * M_PI / m;

         FF_ALLOC_ARRAY_OR_GOTO(tctx->avctx, tctx->cos_tabs[i],
                          (m / 4), sizeof(*tctx->cos_tabs[i]), alloc_fail);

         for (j = 0; j <= m / 8; j++)
             tctx->cos_tabs[i][j] = cos((2 * j + 1) * freq);
         for (j = 1; j < m / 8; j++)
             tctx->cos_tabs[i][m / 4 - j] = tctx->cos_tabs[i][j];

     }
 

     ff_init_ff_sine_windows(av_log2(size_m));

     ff_init_ff_sine_windows(av_log2(size_s / 2));

     ff_init_ff_sine_windows(av_log2(mtab->size));

 
     return 0;

 alloc_fail:
     return AVERROR(ENOMEM);

 }
 
 /**
  * Interpret the data as if it were a num_blocks x line_len[0] matrix and for
  * each line do a cyclic permutation, i.e.
  * abcdefghijklm -> defghijklmabc
  * where the amount to be shifted is evaluated depending on the column.
  */
 static void permutate_in_line(int16_t *tab, int num_vect, int num_blocks,
                               int block_size,
                               const uint8_t line_len[2], int length_div,

                               enum TwinVQFrameType ftype)

 {

     int i, j;

     for (i = 0; i < line_len[0]; i++) {

         int shift;
 

         if (num_blocks == 1                                    ||
             (ftype == TWINVQ_FT_LONG && num_vect % num_blocks) ||
             (ftype != TWINVQ_FT_LONG && num_vect & 1)          ||

             i == line_len[1]) {
             shift = 0;

         } else if (ftype == TWINVQ_FT_LONG) {

             shift = i;
         } else

             shift = i * i;

         for (j = 0; j < num_vect && (j + num_vect * i < block_size * num_blocks); j++)
             tab[i * num_vect + j] = i * num_vect + (j + shift) % num_vect;

     }
 }
 
 /**
  * Interpret the input data as in the following table:
  *

  * @verbatim

  *
  * abcdefgh
  * ijklmnop
  * qrstuvw
  * x123456
  *

  * @endverbatim

  *
  * and transpose it, giving the output
  * aiqxbjr1cks2dlt3emu4fvn5gow6hp
  */
 static void transpose_perm(int16_t *out, int16_t *in, int num_vect,
                            const uint8_t line_len[2], int length_div)
 {

     int i, j;
     int cont = 0;
 

     for (i = 0; i < num_vect; i++)
         for (j = 0; j < line_len[i >= length_div]; j++)

             out[cont++] = in[j * num_vect + i];

 }
 
 static void linear_perm(int16_t *out, int16_t *in, int n_blocks, int size)
 {

     int block_size = size / n_blocks;

     int i;
 

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

         out[i] = block_size * (in[i] % n_blocks) + in[i] / n_blocks;
 }
 

 static av_cold void construct_perm_table(TwinVQContext *tctx,
                                          enum TwinVQFrameType ftype)

 {

     int block_size, size;

     const TwinVQModeTab *mtab = tctx->mtab;

     int16_t *tmp_perm = (int16_t *)tctx->tmp_buf;

     if (ftype == TWINVQ_FT_PPC) {

         size       = tctx->avctx->channels;

         block_size = mtab->ppc_shape_len;

     } else {
         size       = tctx->avctx->channels * mtab->fmode[ftype].sub;

         block_size = mtab->size / mtab->fmode[ftype].sub;

     }

 
     permutate_in_line(tmp_perm, tctx->n_div[ftype], size,
                       block_size, tctx->length[ftype],
                       tctx->length_change[ftype], ftype);
 
     transpose_perm(tctx->permut[ftype], tmp_perm, tctx->n_div[ftype],
                    tctx->length[ftype], tctx->length_change[ftype]);
 
     linear_perm(tctx->permut[ftype], tctx->permut[ftype], size,

                 size * block_size);

 }
 

 static av_cold void init_bitstream_params(TwinVQContext *tctx)

 {

     const TwinVQModeTab *mtab = tctx->mtab;
     int n_ch                  = tctx->avctx->channels;
     int total_fr_bits         = tctx->avctx->bit_rate * mtab->size /
                                 tctx->avctx->sample_rate;

     int lsp_bits_per_block = n_ch * (mtab->lsp_bit0 + mtab->lsp_bit1 +
                                      mtab->lsp_split * mtab->lsp_bit2);

     int ppc_bits = n_ch * (mtab->pgain_bit + mtab->ppc_shape_bit +
                            mtab->ppc_period_bit);

     int bsize_no_main_cb[3], bse_bits[3], i;

     enum TwinVQFrameType frametype;

     for (i = 0; i < 3; i++)

         // +1 for history usage switch
         bse_bits[i] = n_ch *

                       (mtab->fmode[i].bark_n_coef *
                        mtab->fmode[i].bark_n_bit + 1);

 
     bsize_no_main_cb[2] = bse_bits[2] + lsp_bits_per_block + ppc_bits +

                           TWINVQ_WINDOW_TYPE_BITS + n_ch * TWINVQ_GAIN_BITS;

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

         bsize_no_main_cb[i] =

             lsp_bits_per_block + n_ch * TWINVQ_GAIN_BITS +
             TWINVQ_WINDOW_TYPE_BITS +
             mtab->fmode[i].sub * (bse_bits[i] + n_ch * TWINVQ_SUB_GAIN_BITS);

     if (tctx->codec == TWINVQ_CODEC_METASOUND && !tctx->is_6kbps) {

         bsize_no_main_cb[1] += 2;
         bsize_no_main_cb[2] += 2;
     }
 

     // The remaining bits are all used for the main spectrum coefficients

     for (i = 0; i < 4; i++) {

         int bit_size, vect_size;

         int rounded_up, rounded_down, num_rounded_down, num_rounded_up;
         if (i == 3) {
             bit_size  = n_ch * mtab->ppc_shape_bit;
             vect_size = n_ch * mtab->ppc_shape_len;
         } else {

             bit_size  = total_fr_bits - bsize_no_main_cb[i];

             vect_size = n_ch * mtab->size;
         }
 
         tctx->n_div[i] = (bit_size + 13) / 14;
 

         rounded_up                     = (bit_size + tctx->n_div[i] - 1) /
                                          tctx->n_div[i];
         rounded_down                   = (bit_size) / tctx->n_div[i];
         num_rounded_down               = rounded_up * tctx->n_div[i] - bit_size;
         num_rounded_up                 = tctx->n_div[i] - num_rounded_down;
         tctx->bits_main_spec[0][i][0]  = (rounded_up + 1)   / 2;
         tctx->bits_main_spec[1][i][0]  =  rounded_up        / 2;
         tctx->bits_main_spec[0][i][1]  = (rounded_down + 1) / 2;
         tctx->bits_main_spec[1][i][1]  =  rounded_down      / 2;

         tctx->bits_main_spec_change[i] = num_rounded_up;
 

         rounded_up             = (vect_size + tctx->n_div[i] - 1) /
                                  tctx->n_div[i];
         rounded_down           = (vect_size) / tctx->n_div[i];
         num_rounded_down       = rounded_up * tctx->n_div[i] - vect_size;
         num_rounded_up         = tctx->n_div[i] - num_rounded_down;
         tctx->length[i][0]     = rounded_up;
         tctx->length[i][1]     = rounded_down;

         tctx->length_change[i] = num_rounded_up;
     }
 

     for (frametype = TWINVQ_FT_SHORT; frametype <= TWINVQ_FT_PPC; frametype++)

         construct_perm_table(tctx, frametype);

 }
 

 av_cold int ff_twinvq_decode_close(AVCodecContext *avctx)

 {

     TwinVQContext *tctx = avctx->priv_data;

     int i;
 
     for (i = 0; i < 3; i++) {
         ff_mdct_end(&tctx->mdct_ctx[i]);

         av_freep(&tctx->cos_tabs[i]);

     }
 

     av_freep(&tctx->curr_frame);
     av_freep(&tctx->spectrum);
     av_freep(&tctx->prev_frame);
     av_freep(&tctx->tmp_buf);

     av_freep(&tctx->fdsp);

 
     return 0;
 }
 

 av_cold int ff_twinvq_decode_init(AVCodecContext *avctx)

 {

     int ret;

     TwinVQContext *tctx = avctx->priv_data;

 
     tctx->avctx       = avctx;

     avctx->sample_fmt = AV_SAMPLE_FMT_FLTP;

     if (!avctx->block_align) {
         avctx->block_align = tctx->frame_size + 7 >> 3;
     } else if (avctx->block_align * 8 < tctx->frame_size) {
         av_log(avctx, AV_LOG_ERROR, "Block align is %d bits, expected %d\n",
                avctx->block_align * 8, tctx->frame_size);
         return AVERROR_INVALIDDATA;
     }
     tctx->frames_per_packet = avctx->block_align * 8 / tctx->frame_size;
     if (tctx->frames_per_packet > TWINVQ_MAX_FRAMES_PER_PACKET) {
         av_log(avctx, AV_LOG_ERROR, "Too many frames per packet (%d)\n",
                tctx->frames_per_packet);
         return AVERROR_INVALIDDATA;
     }
 

     tctx->fdsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT);

     if (!tctx->fdsp) {
         ff_twinvq_decode_close(avctx);
         return AVERROR(ENOMEM);
     }

     if ((ret = init_mdct_win(tctx))) {
         av_log(avctx, AV_LOG_ERROR, "Error initializing MDCT\n");

         ff_twinvq_decode_close(avctx);

         return ret;
     }

     init_bitstream_params(tctx);
 

     twinvq_memset_float(tctx->bark_hist[0][0], 0.1,
                         FF_ARRAY_ELEMS(tctx->bark_hist));

 
     return 0;
 }