/*

  * Copyright (c) 2007-2008 CSIRO
  * Copyright (c) 2007-2009 Xiph.Org Foundation
  * Copyright (c) 2008-2009 Gregory Maxwell

  * Copyright (c) 2012 Andrew D'Addesio
  * Copyright (c) 2013-2014 Mozilla Corporation

  * Copyright (c) 2017 Rostislav Pehlivanov <atomnuker@gmail.com>

  *
  * 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 "opustab.h"
 #include "opus_pvq.h"
 
 #define CELT_PVQ_U(n, k) (ff_celt_pvq_u_row[FFMIN(n, k)][FFMAX(n, k)])
 #define CELT_PVQ_V(n, k) (CELT_PVQ_U(n, k) + CELT_PVQ_U(n, (k) + 1))
 
 static inline int16_t celt_cos(int16_t x)
 {
     x = (MUL16(x, x) + 4096) >> 13;
     x = (32767-x) + ROUND_MUL16(x, (-7651 + ROUND_MUL16(x, (8277 + ROUND_MUL16(-626, x)))));

     return x + 1;

 }
 
 static inline int celt_log2tan(int isin, int icos)
 {
     int lc, ls;
     lc = opus_ilog(icos);
     ls = opus_ilog(isin);
     icos <<= 15 - lc;
     isin <<= 15 - ls;
     return (ls << 11) - (lc << 11) +
            ROUND_MUL16(isin, ROUND_MUL16(isin, -2597) + 7932) -
            ROUND_MUL16(icos, ROUND_MUL16(icos, -2597) + 7932);
 }
 
 static inline int celt_bits2pulses(const uint8_t *cache, int bits)
 {
     // TODO: Find the size of cache and make it into an array in the parameters list
     int i, low = 0, high;
 
     high = cache[0];
     bits--;
 
     for (i = 0; i < 6; i++) {
         int center = (low + high + 1) >> 1;
         if (cache[center] >= bits)
             high = center;
         else
             low = center;
     }
 
     return (bits - (low == 0 ? -1 : cache[low]) <= cache[high] - bits) ? low : high;
 }
 
 static inline int celt_pulses2bits(const uint8_t *cache, int pulses)
 {
     // TODO: Find the size of cache and make it into an array in the parameters list
    return (pulses == 0) ? 0 : cache[pulses] + 1;
 }
 
 static inline void celt_normalize_residual(const int * av_restrict iy, float * av_restrict X,
                                            int N, float g)
 {
     int i;
     for (i = 0; i < N; i++)
         X[i] = g * iy[i];
 }
 

 static void celt_exp_rotation_impl(float *X, uint32_t len, uint32_t stride,
                                    float c, float s)

 {
     float *Xptr;
     int i;
 
     Xptr = X;
     for (i = 0; i < len - stride; i++) {

         float x1     = Xptr[0];
         float x2     = Xptr[stride];

         Xptr[stride] = c * x2 + s * x1;
         *Xptr++      = c * x1 - s * x2;
     }
 
     Xptr = &X[len - 2 * stride - 1];
     for (i = len - 2 * stride - 1; i >= 0; i--) {

         float x1     = Xptr[0];
         float x2     = Xptr[stride];

         Xptr[stride] = c * x2 + s * x1;
         *Xptr--      = c * x1 - s * x2;
     }
 }
 
 static inline void celt_exp_rotation(float *X, uint32_t len,
                                      uint32_t stride, uint32_t K,

                                      enum CeltSpread spread, const int encode)

 {
     uint32_t stride2 = 0;
     float c, s;
     float gain, theta;
     int i;
 
     if (2*K >= len || spread == CELT_SPREAD_NONE)
         return;
 
     gain = (float)len / (len + (20 - 5*spread) * K);
     theta = M_PI * gain * gain / 4;
 
     c = cosf(theta);
     s = sinf(theta);
 
     if (len >= stride << 3) {
         stride2 = 1;
         /* This is just a simple (equivalent) way of computing sqrt(len/stride) with rounding.
         It's basically incrementing long as (stride2+0.5)^2 < len/stride. */
         while ((stride2 * stride2 + stride2) * stride + (stride >> 2) < len)
             stride2++;
     }
 
     len /= stride;
     for (i = 0; i < stride; i++) {

         if (encode) {
             celt_exp_rotation_impl(X + i * len, len, 1, c, -s);
             if (stride2)
                 celt_exp_rotation_impl(X + i * len, len, stride2, s, -c);
         } else {
             if (stride2)
                 celt_exp_rotation_impl(X + i * len, len, stride2, s, c);
             celt_exp_rotation_impl(X + i * len, len, 1, c, s);
         }

     }
 }
 
 static inline uint32_t celt_extract_collapse_mask(const int *iy, uint32_t N, uint32_t B)
 {

     int i, j, N0 = N / B;
     uint32_t collapse_mask = 0;

 
     if (B <= 1)
         return 1;
 
     for (i = 0; i < B; i++)
         for (j = 0; j < N0; j++)

             collapse_mask |= (!!iy[i*N0+j]) << i;

     return collapse_mask;
 }
 
 static inline void celt_stereo_merge(float *X, float *Y, float mid, int N)
 {
     int i;
     float xp = 0, side = 0;
     float E[2];
     float mid2;

     float gain[2];

 
     /* Compute the norm of X+Y and X-Y as |X|^2 + |Y|^2 +/- sum(xy) */
     for (i = 0; i < N; i++) {
         xp   += X[i] * Y[i];
         side += Y[i] * Y[i];
     }
 
     /* Compensating for the mid normalization */
     xp *= mid;
     mid2 = mid;
     E[0] = mid2 * mid2 + side - 2 * xp;
     E[1] = mid2 * mid2 + side + 2 * xp;
     if (E[0] < 6e-4f || E[1] < 6e-4f) {
         for (i = 0; i < N; i++)
             Y[i] = X[i];
         return;
     }
 

     gain[0] = 1.0f / sqrtf(E[0]);
     gain[1] = 1.0f / sqrtf(E[1]);

 
     for (i = 0; i < N; i++) {
         float value[2];
         /* Apply mid scaling (side is already scaled) */
         value[0] = mid * X[i];
         value[1] = Y[i];
         X[i] = gain[0] * (value[0] - value[1]);
         Y[i] = gain[1] * (value[0] + value[1]);
     }
 }
 
 static void celt_interleave_hadamard(float *tmp, float *X, int N0,
                                      int stride, int hadamard)
 {

     int i, j, N = N0*stride;
     const uint8_t *order = &ff_celt_hadamard_order[hadamard ? stride - 2 : 30];

     for (i = 0; i < stride; i++)
         for (j = 0; j < N0; j++)
             tmp[j*stride+i] = X[order[i]*N0+j];

     memcpy(X, tmp, N*sizeof(float));

 }
 
 static void celt_deinterleave_hadamard(float *tmp, float *X, int N0,
                                        int stride, int hadamard)
 {

     int i, j, N = N0*stride;
     const uint8_t *order = &ff_celt_hadamard_order[hadamard ? stride - 2 : 30];

     for (i = 0; i < stride; i++)
         for (j = 0; j < N0; j++)
             tmp[order[i]*N0+j] = X[j*stride+i];

     memcpy(X, tmp, N*sizeof(float));

 }
 
 static void celt_haar1(float *X, int N0, int stride)
 {
     int i, j;
     N0 >>= 1;
     for (i = 0; i < stride; i++) {
         for (j = 0; j < N0; j++) {
             float x0 = X[stride * (2 * j + 0) + i];
             float x1 = X[stride * (2 * j + 1) + i];
             X[stride * (2 * j + 0) + i] = (x0 + x1) * M_SQRT1_2;
             X[stride * (2 * j + 1) + i] = (x0 - x1) * M_SQRT1_2;
         }
     }
 }
 
 static inline int celt_compute_qn(int N, int b, int offset, int pulse_cap,

                                   int stereo)

 {
     int qn, qb;
     int N2 = 2 * N - 1;

     if (stereo && N == 2)

         N2--;
 
     /* The upper limit ensures that in a stereo split with itheta==16384, we'll
      * always have enough bits left over to code at least one pulse in the
      * side; otherwise it would collapse, since it doesn't get folded. */
     qb = FFMIN3(b - pulse_cap - (4 << 3), (b + N2 * offset) / N2, 8 << 3);
     qn = (qb < (1 << 3 >> 1)) ? 1 : ((ff_celt_qn_exp2[qb & 0x7] >> (14 - (qb >> 3))) + 1) >> 1 << 1;
     return qn;
 }
 

 /* Convert the quantized vector to an index */

 static inline uint32_t celt_icwrsi(uint32_t N, uint32_t K, const int *y)

 {
     int i, idx = 0, sum = 0;
     for (i = N - 1; i >= 0; i--) {
         const uint32_t i_s = CELT_PVQ_U(N - i, sum + FFABS(y[i]) + 1);
         idx += CELT_PVQ_U(N - i, sum) + (y[i] < 0)*i_s;
         sum += FFABS(y[i]);
     }
     return idx;
 }
 

 // this code was adapted from libopus
 static inline uint64_t celt_cwrsi(uint32_t N, uint32_t K, uint32_t i, int *y)
 {
     uint64_t norm = 0;

     uint32_t q, p;

     int s, val;
     int k0;
 
     while (N > 2) {
         /*Lots of pulses case:*/
         if (K >= N) {
             const uint32_t *row = ff_celt_pvq_u_row[N];
 
             /* Are the pulses in this dimension negative? */
             p  = row[K + 1];
             s  = -(i >= p);
             i -= p & s;
 
             /*Count how many pulses were placed in this dimension.*/
             k0 = K;
             q = row[N];
             if (q > i) {
                 K = N;
                 do {
                     p = ff_celt_pvq_u_row[--K][N];
                 } while (p > i);
             } else
                 for (p = row[K]; p > i; p = row[K])
                     K--;
 
             i    -= p;
             val   = (k0 - K + s) ^ s;
             norm += val * val;
             *y++  = val;
         } else { /*Lots of dimensions case:*/
             /*Are there any pulses in this dimension at all?*/
             p = ff_celt_pvq_u_row[K    ][N];
             q = ff_celt_pvq_u_row[K + 1][N];
 
             if (p <= i && i < q) {
                 i -= p;
                 *y++ = 0;
             } else {
                 /*Are the pulses in this dimension negative?*/
                 s  = -(i >= q);
                 i -= q & s;
 
                 /*Count how many pulses were placed in this dimension.*/
                 k0 = K;
                 do p = ff_celt_pvq_u_row[--K][N];
                 while (p > i);
 
                 i    -= p;
                 val   = (k0 - K + s) ^ s;
                 norm += val * val;
                 *y++  = val;
             }
         }
         N--;
     }
 
     /* N == 2 */
     p  = 2 * K + 1;
     s  = -(i >= p);
     i -= p & s;
     k0 = K;
     K  = (i + 1) / 2;
 
     if (K)
         i -= 2 * K - 1;
 
     val   = (k0 - K + s) ^ s;
     norm += val * val;
     *y++  = val;
 
     /* N==1 */
     s     = -i;
     val   = (K + s) ^ s;
     norm += val * val;
     *y    = val;
 
     return norm;
 }
 

 static inline void celt_encode_pulses(OpusRangeCoder *rc, int *y, uint32_t N, uint32_t K)
 {

     ff_opus_rc_enc_uint(rc, celt_icwrsi(N, K, y), CELT_PVQ_V(N, K));

 }
 

 static inline float celt_decode_pulses(OpusRangeCoder *rc, int *y, uint32_t N, uint32_t K)
 {
     const uint32_t idx = ff_opus_rc_dec_uint(rc, CELT_PVQ_V(N, K));
     return celt_cwrsi(N, K, idx, y);
 }
 

 /*
  * Faster than libopus's search, operates entirely in the signed domain.
  * Slightly worse/better depending on N, K and the input vector.
  */

 static float ppp_pvq_search_c(float *X, int *y, int K, int N)

 {

     int i, y_norm = 0;
     float res = 0.0f, xy_norm = 0.0f;

 
     for (i = 0; i < N; i++)
         res += FFABS(X[i]);
 

     res = K/(res + FLT_EPSILON);

 
     for (i = 0; i < N; i++) {
         y[i] = lrintf(res*X[i]);
         y_norm  += y[i]*y[i];
         xy_norm += y[i]*X[i];
         K -= FFABS(y[i]);
     }
 
     while (K) {

         int max_idx = 0, phase = FFSIGN(K);

         float max_num = 0.0f;

         float max_den = 1.0f;

         y_norm += 1.0f;
 
         for (i = 0; i < N; i++) {

             /* If the sum has been overshot and the best place has 0 pulses allocated
              * to it, attempting to decrease it further will actually increase the
              * sum. Prevent this by disregarding any 0 positions when decrementing. */
             const int ca = 1 ^ ((y[i] == 0) & (phase < 0));

             const int y_new = y_norm  + 2*phase*FFABS(y[i]);

             float xy_new = xy_norm + 1*phase*FFABS(X[i]);
             xy_new = xy_new * xy_new;

             if (ca && (max_den*xy_new) > (y_new*max_num)) {

                 max_den = y_new;
                 max_num = xy_new;
                 max_idx = i;
             }
         }
 
         K -= phase;
 
         phase *= FFSIGN(X[max_idx]);
         xy_norm += 1*phase*X[max_idx];
         y_norm  += 2*phase*y[max_idx];
         y[max_idx] += phase;
     }

     return (float)y_norm;

 }
 
 static uint32_t celt_alg_quant(OpusRangeCoder *rc, float *X, uint32_t N, uint32_t K,

                                enum CeltSpread spread, uint32_t blocks, float gain,

                                CeltPVQ *pvq)

 {

     int *y = pvq->qcoeff;

 
     celt_exp_rotation(X, N, blocks, K, spread, 1);

     gain /= sqrtf(pvq->pvq_search(X, y, K, N));

     celt_encode_pulses(rc, y,  N, K);

     celt_normalize_residual(y, X, N, gain);
     celt_exp_rotation(X, N, blocks, K, spread, 0);

     return celt_extract_collapse_mask(y, N, blocks);
 }
 

 /** Decode pulse vector and combine the result with the pitch vector to produce
     the final normalised signal in the current band. */
 static uint32_t celt_alg_unquant(OpusRangeCoder *rc, float *X, uint32_t N, uint32_t K,

                                  enum CeltSpread spread, uint32_t blocks, float gain,

                                  CeltPVQ *pvq)

 {

     int *y = pvq->qcoeff;

 
     gain /= sqrtf(celt_decode_pulses(rc, y, N, K));
     celt_normalize_residual(y, X, N, gain);

     celt_exp_rotation(X, N, blocks, K, spread, 0);

     return celt_extract_collapse_mask(y, N, blocks);
 }
 

 static int celt_calc_theta(const float *X, const float *Y, int coupling, int N)
 {

     int i;

     float e[2] = { 0.0f, 0.0f };

     if (coupling) { /* Coupling case */
         for (i = 0; i < N; i++) {
             e[0] += (X[i] + Y[i])*(X[i] + Y[i]);
             e[1] += (X[i] - Y[i])*(X[i] - Y[i]);
         }
     } else {
         for (i = 0; i < N; i++) {
             e[0] += X[i]*X[i];
             e[1] += Y[i]*Y[i];

         }
     }
     return lrintf(32768.0f*atan2f(sqrtf(e[1]), sqrtf(e[0]))/M_PI);
 }
 
 static void celt_stereo_is_decouple(float *X, float *Y, float e_l, float e_r, int N)
 {
     int i;
     const float energy_n = 1.0f/(sqrtf(e_l*e_l + e_r*e_r) + FLT_EPSILON);
     e_l *= energy_n;
     e_r *= energy_n;
     for (i = 0; i < N; i++)
         X[i] = e_l*X[i] + e_r*Y[i];
 }
 
 static void celt_stereo_ms_decouple(float *X, float *Y, int N)
 {
     int i;
     for (i = 0; i < N; i++) {
         const float Xret = X[i];

         X[i] = (X[i] + Y[i])*M_SQRT1_2;
         Y[i] = (Y[i] - Xret)*M_SQRT1_2;

     }
 }
 

 static av_always_inline uint32_t quant_band_template(CeltPVQ *pvq, CeltFrame *f,
                                                      OpusRangeCoder *rc,
                                                      const int band, float *X,
                                                      float *Y, int N, int b,
                                                      uint32_t blocks, float *lowband,
                                                      int duration, float *lowband_out,
                                                      int level, float gain,
                                                      float *lowband_scratch,
                                                      int fill, int quant,
                                                      QUANT_FN(*rec))

 {

     int i;

     const uint8_t *cache;

     int stereo = !!Y, split = stereo;

     int imid = 0, iside = 0;

     uint32_t N0 = N;

     int N_B = N / blocks;

     int N_B0 = N_B;

     int B0 = blocks;
     int time_divide = 0;
     int recombine = 0;
     int inv = 0;
     float mid = 0, side = 0;
     int longblocks = (B0 == 1);
     uint32_t cm = 0;
 
     if (N == 1) {
         float *x = X;

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

             int sign = 0;
             if (f->remaining2 >= 1 << 3) {
                 if (quant) {
                     sign = x[0] < 0;
                     ff_opus_rc_put_raw(rc, sign, 1);
                 } else {
                     sign = ff_opus_rc_get_raw(rc, 1);
                 }

                 f->remaining2 -= 1 << 3;
             }

             x[0] = 1.0f - 2.0f*sign;

             x = Y;
         }
         if (lowband_out)
             lowband_out[0] = X[0];
         return 1;
     }
 

     if (!stereo && level == 0) {

         int tf_change = f->tf_change[band];
         int k;
         if (tf_change > 0)
             recombine = tf_change;
         /* Band recombining to increase frequency resolution */
 
         if (lowband &&
             (recombine || ((N_B & 1) == 0 && tf_change < 0) || B0 > 1)) {

             for (i = 0; i < N; i++)
                 lowband_scratch[i] = lowband[i];

             lowband = lowband_scratch;
         }
 
         for (k = 0; k < recombine; k++) {

             if (quant || lowband)
                 celt_haar1(quant ? X : lowband, N >> k, 1 << k);

             fill = ff_celt_bit_interleave[fill & 0xF] | ff_celt_bit_interleave[fill >> 4] << 2;
         }
         blocks >>= recombine;
         N_B <<= recombine;
 
         /* Increasing the time resolution */
         while ((N_B & 1) == 0 && tf_change < 0) {

             if (quant || lowband)
                 celt_haar1(quant ? X : lowband, N_B, blocks);

             fill |= fill << blocks;
             blocks <<= 1;
             N_B >>= 1;
             time_divide++;
             tf_change++;
         }
         B0 = blocks;

         N_B0 = N_B;

 
         /* Reorganize the samples in time order instead of frequency order */

         if (B0 > 1 && (quant || lowband))

             celt_deinterleave_hadamard(pvq->hadamard_tmp, quant ? X : lowband,

                                        N_B >> recombine, B0 << recombine,
                                        longblocks);

     }
 
     /* If we need 1.5 more bit than we can produce, split the band in two. */
     cache = ff_celt_cache_bits +
             ff_celt_cache_index[(duration + 1) * CELT_MAX_BANDS + band];

     if (!stereo && duration >= 0 && b > cache[cache[0]] + 12 && N > 2) {

         N >>= 1;
         Y = X + N;
         split = 1;
         duration -= 1;
         if (blocks == 1)
             fill = (fill & 1) | (fill << 1);
         blocks = (blocks + 1) >> 1;
     }
 
     if (split) {
         int qn;

         int itheta = quant ? celt_calc_theta(X, Y, stereo, N) : 0;

         int mbits, sbits, delta;
         int qalloc;
         int pulse_cap;
         int offset;
         int orig_fill;
         int tell;
 
         /* Decide on the resolution to give to the split parameter theta */
         pulse_cap = ff_celt_log_freq_range[band] + duration * 8;

         offset = (pulse_cap >> 1) - (stereo && N == 2 ? CELT_QTHETA_OFFSET_TWOPHASE :

                                                           CELT_QTHETA_OFFSET);

         qn = (stereo && band >= f->intensity_stereo) ? 1 :
              celt_compute_qn(N, b, offset, pulse_cap, stereo);

         tell = opus_rc_tell_frac(rc);
         if (qn != 1) {

             if (quant)
                 itheta = (itheta*qn + 8192) >> 14;

             /* Entropy coding of the angle. We use a uniform pdf for the
              * time split, a step for stereo, and a triangular one for the rest. */

             if (quant) {
                 if (stereo && N > 2)
                     ff_opus_rc_enc_uint_step(rc, itheta, qn / 2);
                 else if (stereo || B0 > 1)
                     ff_opus_rc_enc_uint(rc, itheta, qn + 1);
                 else
                     ff_opus_rc_enc_uint_tri(rc, itheta, qn);
                 itheta = itheta * 16384 / qn;
                 if (stereo) {
                     if (itheta == 0)
                         celt_stereo_is_decouple(X, Y, f->block[0].lin_energy[band],
                                                 f->block[1].lin_energy[band], N);
                     else
                         celt_stereo_ms_decouple(X, Y, N);
                 }
             } else {
                 if (stereo && N > 2)
                     itheta = ff_opus_rc_dec_uint_step(rc, qn / 2);
                 else if (stereo || B0 > 1)
                     itheta = ff_opus_rc_dec_uint(rc, qn+1);

                 else

                     itheta = ff_opus_rc_dec_uint_tri(rc, qn);
                 itheta = itheta * 16384 / qn;

             }

         } else if (stereo) {

             if (quant) {
                 inv = itheta > 8192;
                  if (inv) {
                     for (i = 0; i < N; i++)
                        Y[i] *= -1;
                  }
                  celt_stereo_is_decouple(X, Y, f->block[0].lin_energy[band],
                                          f->block[1].lin_energy[band], N);
 
                 if (b > 2 << 3 && f->remaining2 > 2 << 3) {
                     ff_opus_rc_enc_log(rc, inv, 2);
                 } else {
                     inv = 0;
                 }

             } else {

                 inv = (b > 2 << 3 && f->remaining2 > 2 << 3) ? ff_opus_rc_dec_log(rc, 2) : 0;

             }
             itheta = 0;
         }
         qalloc = opus_rc_tell_frac(rc) - tell;
         b -= qalloc;
 
         orig_fill = fill;
         if (itheta == 0) {
             imid = 32767;
             iside = 0;
             fill = av_mod_uintp2(fill, blocks);
             delta = -16384;
         } else if (itheta == 16384) {
             imid = 0;
             iside = 32767;
             fill &= ((1 << blocks) - 1) << blocks;
             delta = 16384;
         } else {
             imid = celt_cos(itheta);
             iside = celt_cos(16384-itheta);
             /* This is the mid vs side allocation that minimizes squared error
             in that band. */
             delta = ROUND_MUL16((N - 1) << 7, celt_log2tan(iside, imid));
         }
 
         mid  = imid  / 32768.0f;
         side = iside / 32768.0f;
 
         /* This is a special case for N=2 that only works for stereo and takes
         advantage of the fact that mid and side are orthogonal to encode
         the side with just one bit. */

         if (N == 2 && stereo) {

             int c;
             int sign = 0;
             float tmp;
             float *x2, *y2;
             mbits = b;
             /* Only need one bit for the side */
             sbits = (itheta != 0 && itheta != 16384) ? 1 << 3 : 0;
             mbits -= sbits;
             c = (itheta > 8192);
             f->remaining2 -= qalloc+sbits;
 
             x2 = c ? Y : X;
             y2 = c ? X : Y;
             if (sbits) {

                 if (quant) {
                     sign = x2[0]*y2[1] - x2[1]*y2[0] < 0;
                     ff_opus_rc_put_raw(rc, sign, 1);
                 } else {
                     sign = ff_opus_rc_get_raw(rc, 1);
                 }

             }
             sign = 1 - 2 * sign;
             /* We use orig_fill here because we want to fold the side, but if
             itheta==16384, we'll have cleared the low bits of fill. */

             cm = rec(pvq, f, rc, band, x2, NULL, N, mbits, blocks, lowband, duration,

                      lowband_out, level, gain, lowband_scratch, orig_fill);

             /* We don't split N=2 bands, so cm is either 1 or 0 (for a fold-collapse),
             and there's no need to worry about mixing with the other channel. */
             y2[0] = -sign * x2[1];
             y2[1] =  sign * x2[0];
             X[0] *= mid;
             X[1] *= mid;
             Y[0] *= side;
             Y[1] *= side;
             tmp = X[0];
             X[0] = tmp - Y[0];
             Y[0] = tmp + Y[0];
             tmp = X[1];
             X[1] = tmp - Y[1];
             Y[1] = tmp + Y[1];
         } else {
             /* "Normal" split code */
             float *next_lowband2     = NULL;
             float *next_lowband_out1 = NULL;
             int next_level = 0;
             int rebalance;

             uint32_t cmt;

 
             /* Give more bits to low-energy MDCTs than they would
              * otherwise deserve */

             if (B0 > 1 && !stereo && (itheta & 0x3fff)) {

                 if (itheta > 8192)
                     /* Rough approximation for pre-echo masking */
                     delta -= delta >> (4 - duration);
                 else
                     /* Corresponds to a forward-masking slope of
                      * 1.5 dB per 10 ms */
                     delta = FFMIN(0, delta + (N << 3 >> (5 - duration)));
             }
             mbits = av_clip((b - delta) / 2, 0, b);
             sbits = b - mbits;
             f->remaining2 -= qalloc;
 

             if (lowband && !stereo)

                 next_lowband2 = lowband + N; /* >32-bit split case */
 
             /* Only stereo needs to pass on lowband_out.
              * Otherwise, it's handled at the end */

             if (stereo)

                 next_lowband_out1 = lowband_out;
             else
                 next_level = level + 1;
 
             rebalance = f->remaining2;
             if (mbits >= sbits) {
                 /* In stereo mode, we do not apply a scaling to the mid
                  * because we need the normalized mid for folding later */

                 cm = rec(pvq, f, rc, band, X, NULL, N, mbits, blocks, lowband,

                          duration, next_lowband_out1, next_level,
                          stereo ? 1.0f : (gain * mid), lowband_scratch, fill);

                 rebalance = mbits - (rebalance - f->remaining2);
                 if (rebalance > 3 << 3 && itheta != 0)
                     sbits += rebalance - (3 << 3);
 
                 /* For a stereo split, the high bits of fill are always zero,
                  * so no folding will be done to the side. */

                 cmt = rec(pvq, f, rc, band, Y, NULL, N, sbits, blocks, next_lowband2,

                           duration, NULL, next_level, gain * side, NULL,
                           fill >> blocks);
                 cm |= cmt << ((B0 >> 1) & (stereo - 1));

             } else {
                 /* For a stereo split, the high bits of fill are always zero,
                  * so no folding will be done to the side. */

                 cm = rec(pvq, f, rc, band, Y, NULL, N, sbits, blocks, next_lowband2,

                          duration, NULL, next_level, gain * side, NULL, fill >> blocks);
                 cm <<= ((B0 >> 1) & (stereo - 1));

                 rebalance = sbits - (rebalance - f->remaining2);
                 if (rebalance > 3 << 3 && itheta != 16384)
                     mbits += rebalance - (3 << 3);
 
                 /* In stereo mode, we do not apply a scaling to the mid because
                  * we need the normalized mid for folding later */

                 cm |= rec(pvq, f, rc, band, X, NULL, N, mbits, blocks, lowband, duration,

                           next_lowband_out1, next_level, stereo ? 1.0f : (gain * mid),
                           lowband_scratch, fill);

             }
         }
     } else {
         /* This is the basic no-split case */
         uint32_t q         = celt_bits2pulses(cache, b);
         uint32_t curr_bits = celt_pulses2bits(cache, q);
         f->remaining2 -= curr_bits;
 
         /* Ensures we can never bust the budget */
         while (f->remaining2 < 0 && q > 0) {
             f->remaining2 += curr_bits;
             curr_bits      = celt_pulses2bits(cache, --q);
             f->remaining2 -= curr_bits;
         }
 
         if (q != 0) {

             /* Finally do the actual (de)quantization */
             if (quant) {
                 cm = celt_alg_quant(rc, X, N, (q < 8) ? q : (8 + (q & 7)) << ((q >> 3) - 1),

                                     f->spread, blocks, gain, pvq);

             } else {
                 cm = celt_alg_unquant(rc, X, N, (q < 8) ? q : (8 + (q & 7)) << ((q >> 3) - 1),

                                       f->spread, blocks, gain, pvq);

             }

         } else {
             /* If there's no pulse, fill the band anyway */
             uint32_t cm_mask = (1 << blocks) - 1;
             fill &= cm_mask;

             if (fill) {

                 if (!lowband) {
                     /* Noise */

                     for (i = 0; i < N; i++)
                         X[i] = (((int32_t)celt_rng(f)) >> 20);

                     cm = cm_mask;
                 } else {
                     /* Folded spectrum */

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

                         /* About 48 dB below the "normal" folding level */

                         X[i] = lowband[i] + (((celt_rng(f)) & 0x8000) ? 1.0f / 256 : -1.0f / 256);

                     }
                     cm = fill;
                 }
                 celt_renormalize_vector(X, N, gain);

             } else {
                 memset(X, 0, N*sizeof(float));

             }
         }
     }
 
     /* This code is used by the decoder and by the resynthesis-enabled encoder */

     if (stereo) {
         if (N > 2)

             celt_stereo_merge(X, Y, mid, N);
         if (inv) {

             for (i = 0; i < N; i++)
                 Y[i] *= -1;

         }
     } else if (level == 0) {
         int k;
 
         /* Undo the sample reorganization going from time order to frequency order */
         if (B0 > 1)

             celt_interleave_hadamard(pvq->hadamard_tmp, X, N_B >> recombine,

                                      B0 << recombine, longblocks);

 
         /* Undo time-freq changes that we did earlier */
         N_B = N_B0;
         blocks = B0;
         for (k = 0; k < time_divide; k++) {
             blocks >>= 1;
             N_B <<= 1;
             cm |= cm >> blocks;
             celt_haar1(X, N_B, blocks);

         }

 
         for (k = 0; k < recombine; k++) {
             cm = ff_celt_bit_deinterleave[cm];
             celt_haar1(X, N0>>k, 1<<k);
         }
         blocks <<= recombine;
 
         /* Scale output for later folding */
         if (lowband_out) {
             float n = sqrtf(N0);

             for (i = 0; i < N0; i++)
                 lowband_out[i] = n * X[i];

         }
         cm = av_mod_uintp2(cm, blocks);

     }
 

     return cm;
 }

 
 static QUANT_FN(pvq_decode_band)

 {

     return quant_band_template(pvq, f, rc, band, X, Y, N, b, blocks, lowband, duration,
                                lowband_out, level, gain, lowband_scratch, fill, 0,
                                pvq->decode_band);

 }
 

 static QUANT_FN(pvq_encode_band)

 {

     return quant_band_template(pvq, f, rc, band, X, Y, N, b, blocks, lowband, duration,
                                lowband_out, level, gain, lowband_scratch, fill, 1,
                                pvq->encode_band);

 }
 

 static float pvq_band_cost(CeltPVQ *pvq, CeltFrame *f, OpusRangeCoder *rc, int band,
                            float *bits, float lambda)

 {
     int i, b = 0;
     uint32_t cm[2] = { (1 << f->blocks) - 1, (1 << f->blocks) - 1 };
     const int band_size = ff_celt_freq_range[band] << f->size;

     float buf[176 * 2], lowband_scratch[176], norm1[176], norm2[176];

     float dist, cost, err_x = 0.0f, err_y = 0.0f;
     float *X = buf;
     float *X_orig = f->block[0].coeffs + (ff_celt_freq_bands[band] << f->size);
     float *Y = (f->channels == 2) ? &buf[176] : NULL;
     float *Y_orig = f->block[1].coeffs + (ff_celt_freq_bands[band] << f->size);
     OPUS_RC_CHECKPOINT_SPAWN(rc);
 
     memcpy(X, X_orig, band_size*sizeof(float));
     if (Y)
         memcpy(Y, Y_orig, band_size*sizeof(float));
 
     f->remaining2 = ((f->framebits << 3) - f->anticollapse_needed) - opus_rc_tell_frac(rc) - 1;
     if (band <= f->coded_bands - 1) {
         int curr_balance = f->remaining / FFMIN(3, f->coded_bands - band);
         b = av_clip_uintp2(FFMIN(f->remaining2 + 1, f->pulses[band] + curr_balance), 14);
     }
 
     if (f->dual_stereo) {

         pvq->encode_band(pvq, f, rc, band, X, NULL, band_size, b / 2, f->blocks, NULL,
                          f->size, norm1, 0, 1.0f, lowband_scratch, cm[0]);

         pvq->encode_band(pvq, f, rc, band, Y, NULL, band_size, b / 2, f->blocks, NULL,
                          f->size, norm2, 0, 1.0f, lowband_scratch, cm[1]);

     } else {

         pvq->encode_band(pvq, f, rc, band, X, Y, band_size, b, f->blocks, NULL, f->size,
                          norm1, 0, 1.0f, lowband_scratch, cm[0] | cm[1]);

     }
 
     for (i = 0; i < band_size; i++) {
         err_x += (X[i] - X_orig[i])*(X[i] - X_orig[i]);

         if (Y)
             err_y += (Y[i] - Y_orig[i])*(Y[i] - Y_orig[i]);

     }
 
     dist = sqrtf(err_x) + sqrtf(err_y);
     cost = OPUS_RC_CHECKPOINT_BITS(rc)/8.0f;
     *bits += cost;
 
     OPUS_RC_CHECKPOINT_ROLLBACK(rc);
 
     return lambda*dist*cost;
 }

 
 int av_cold ff_celt_pvq_init(CeltPVQ **pvq)
 {
     CeltPVQ *s = av_malloc(sizeof(CeltPVQ));
     if (!s)
         return AVERROR(ENOMEM);
 
     s->pvq_search         = ppp_pvq_search_c;
     s->decode_band        = pvq_decode_band;
     s->encode_band        = pvq_encode_band;
     s->band_cost          = pvq_band_cost;
 

     if (ARCH_X86)
         ff_opus_dsp_init_x86(s);
 

     *pvq = s;
 
     return 0;
 }
 
 void av_cold ff_celt_pvq_uninit(CeltPVQ **pvq)
 {
     av_freep(pvq);
 }