Add libopus 1.0.2 and libopusfile 0.2

1 files changed, 1302 insertions, 0 deletions

diff --git a/src/opus-1.0.2/celt/bands.c b/src/opus-1.0.2/celt/bands.c
new file mode 100644
index 00000000..3be543c3
--- /dev/null
+++ b/src/opus-1.0.2/celt/bands.c
@@ -0,0 +1,1302 @@
+/* Copyright (c) 2007-2008 CSIRO
+   Copyright (c) 2007-2009 Xiph.Org Foundation
+   Copyright (c) 2008-2009 Gregory Maxwell
+   Written by Jean-Marc Valin and Gregory Maxwell */
+/*
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+
+   - Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+   - Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <math.h>
+#include "bands.h"
+#include "modes.h"
+#include "vq.h"
+#include "cwrs.h"
+#include "stack_alloc.h"
+#include "os_support.h"
+#include "mathops.h"
+#include "rate.h"
+
+opus_uint32 celt_lcg_rand(opus_uint32 seed)
+{
+   return 1664525 * seed + 1013904223;
+}
+
+/* This is a cos() approximation designed to be bit-exact on any platform. Bit exactness
+   with this approximation is important because it has an impact on the bit allocation */
+static opus_int16 bitexact_cos(opus_int16 x)
+{
+   opus_int32 tmp;
+   opus_int16 x2;
+   tmp = (4096+((opus_int32)(x)*(x)))>>13;
+   celt_assert(tmp<=32767);
+   x2 = tmp;
+   x2 = (32767-x2) + FRAC_MUL16(x2, (-7651 + FRAC_MUL16(x2, (8277 + FRAC_MUL16(-626, x2)))));
+   celt_assert(x2<=32766);
+   return 1+x2;
+}
+
+static int bitexact_log2tan(int isin,int icos)
+{
+   int lc;
+   int ls;
+   lc=EC_ILOG(icos);
+   ls=EC_ILOG(isin);
+   icos<<=15-lc;
+   isin<<=15-ls;
+   return (ls-lc)*(1<<11)
+         +FRAC_MUL16(isin, FRAC_MUL16(isin, -2597) + 7932)
+         -FRAC_MUL16(icos, FRAC_MUL16(icos, -2597) + 7932);
+}
+
+#ifdef FIXED_POINT
+/* Compute the amplitude (sqrt energy) in each of the bands */
+void compute_band_energies(const CELTMode *m, const celt_sig *X, celt_ener *bandE, int end, int C, int M)
+{
+   int i, c, N;
+   const opus_int16 *eBands = m->eBands;
+   N = M*m->shortMdctSize;
+   c=0; do {
+      for (i=0;i<end;i++)
+      {
+         int j;
+         opus_val32 maxval=0;
+         opus_val32 sum = 0;
+
+         j=M*eBands[i]; do {
+            maxval = MAX32(maxval, X[j+c*N]);
+            maxval = MAX32(maxval, -X[j+c*N]);
+         } while (++j<M*eBands[i+1]);
+
+         if (maxval > 0)
+         {
+            int shift = celt_ilog2(maxval)-10;
+            j=M*eBands[i]; do {
+               sum = MAC16_16(sum, EXTRACT16(VSHR32(X[j+c*N],shift)),
+                                   EXTRACT16(VSHR32(X[j+c*N],shift)));
+            } while (++j<M*eBands[i+1]);
+            /* We're adding one here to ensure the normalized band isn't larger than unity norm */
+            bandE[i+c*m->nbEBands] = EPSILON+VSHR32(EXTEND32(celt_sqrt(sum)),-shift);
+         } else {
+            bandE[i+c*m->nbEBands] = EPSILON;
+         }
+         /*printf ("%f ", bandE[i+c*m->nbEBands]);*/
+      }
+   } while (++c<C);
+   /*printf ("\n");*/
+}
+
+/* Normalise each band such that the energy is one. */
+void normalise_bands(const CELTMode *m, const celt_sig * OPUS_RESTRICT freq, celt_norm * OPUS_RESTRICT X, const celt_ener *bandE, int end, int C, int M)
+{
+   int i, c, N;
+   const opus_int16 *eBands = m->eBands;
+   N = M*m->shortMdctSize;
+   c=0; do {
+      i=0; do {
+         opus_val16 g;
+         int j,shift;
+         opus_val16 E;
+         shift = celt_zlog2(bandE[i+c*m->nbEBands])-13;
+         E = VSHR32(bandE[i+c*m->nbEBands], shift);
+         g = EXTRACT16(celt_rcp(SHL32(E,3)));
+         j=M*eBands[i]; do {
+            X[j+c*N] = MULT16_16_Q15(VSHR32(freq[j+c*N],shift-1),g);
+         } while (++j<M*eBands[i+1]);
+      } while (++i<end);
+   } while (++c<C);
+}
+
+#else /* FIXED_POINT */
+/* Compute the amplitude (sqrt energy) in each of the bands */
+void compute_band_energies(const CELTMode *m, const celt_sig *X, celt_ener *bandE, int end, int C, int M)
+{
+   int i, c, N;
+   const opus_int16 *eBands = m->eBands;
+   N = M*m->shortMdctSize;
+   c=0; do {
+      for (i=0;i<end;i++)
+      {
+         int j;
+         opus_val32 sum = 1e-27f;
+         for (j=M*eBands[i];j<M*eBands[i+1];j++)
+            sum += X[j+c*N]*X[j+c*N];
+         bandE[i+c*m->nbEBands] = celt_sqrt(sum);
+         /*printf ("%f ", bandE[i+c*m->nbEBands]);*/
+      }
+   } while (++c<C);
+   /*printf ("\n");*/
+}
+
+/* Normalise each band such that the energy is one. */
+void normalise_bands(const CELTMode *m, const celt_sig * OPUS_RESTRICT freq, celt_norm * OPUS_RESTRICT X, const celt_ener *bandE, int end, int C, int M)
+{
+   int i, c, N;
+   const opus_int16 *eBands = m->eBands;
+   N = M*m->shortMdctSize;
+   c=0; do {
+      for (i=0;i<end;i++)
+      {
+         int j;
+         opus_val16 g = 1.f/(1e-27f+bandE[i+c*m->nbEBands]);
+         for (j=M*eBands[i];j<M*eBands[i+1];j++)
+            X[j+c*N] = freq[j+c*N]*g;
+      }
+   } while (++c<C);
+}
+
+#endif /* FIXED_POINT */
+
+/* De-normalise the energy to produce the synthesis from the unit-energy bands */
+void denormalise_bands(const CELTMode *m, const celt_norm * OPUS_RESTRICT X, celt_sig * OPUS_RESTRICT freq, const celt_ener *bandE, int end, int C, int M)
+{
+   int i, c, N;
+   const opus_int16 *eBands = m->eBands;
+   N = M*m->shortMdctSize;
+   celt_assert2(C<=2, "denormalise_bands() not implemented for >2 channels");
+   c=0; do {
+      celt_sig * OPUS_RESTRICT f;
+      const celt_norm * OPUS_RESTRICT x;
+      f = freq+c*N;
+      x = X+c*N;
+      for (i=0;i<end;i++)
+      {
+         int j, band_end;
+         opus_val32 g = SHR32(bandE[i+c*m->nbEBands],1);
+         j=M*eBands[i];
+         band_end = M*eBands[i+1];
+         do {
+            *f++ = SHL32(MULT16_32_Q15(*x, g),2);
+            x++;
+         } while (++j<band_end);
+      }
+      for (i=M*eBands[end];i<N;i++)
+         *f++ = 0;
+   } while (++c<C);
+}
+
+/* This prevents energy collapse for transients with multiple short MDCTs */
+void anti_collapse(const CELTMode *m, celt_norm *X_, unsigned char *collapse_masks, int LM, int C, int size,
+      int start, int end, opus_val16 *logE, opus_val16 *prev1logE,
+      opus_val16 *prev2logE, int *pulses, opus_uint32 seed)
+{
+   int c, i, j, k;
+   for (i=start;i<end;i++)
+   {
+      int N0;
+      opus_val16 thresh, sqrt_1;
+      int depth;
+#ifdef FIXED_POINT
+      int shift;
+      opus_val32 thresh32;
+#endif
+
+      N0 = m->eBands[i+1]-m->eBands[i];
+      /* depth in 1/8 bits */
+      depth = (1+pulses[i])/((m->eBands[i+1]-m->eBands[i])<<LM);
+
+#ifdef FIXED_POINT
+      thresh32 = SHR32(celt_exp2(-SHL16(depth, 10-BITRES)),1);
+      thresh = MULT16_32_Q15(QCONST16(0.5f, 15), MIN32(32767,thresh32));
+      {
+         opus_val32 t;
+         t = N0<<LM;
+         shift = celt_ilog2(t)>>1;
+         t = SHL32(t, (7-shift)<<1);
+         sqrt_1 = celt_rsqrt_norm(t);
+      }
+#else
+      thresh = .5f*celt_exp2(-.125f*depth);
+      sqrt_1 = celt_rsqrt(N0<<LM);
+#endif
+
+      c=0; do
+      {
+         celt_norm *X;
+         opus_val16 prev1;
+         opus_val16 prev2;
+         opus_val32 Ediff;
+         opus_val16 r;
+         int renormalize=0;
+         prev1 = prev1logE[c*m->nbEBands+i];
+         prev2 = prev2logE[c*m->nbEBands+i];
+         if (C==1)
+         {
+            prev1 = MAX16(prev1,prev1logE[m->nbEBands+i]);
+            prev2 = MAX16(prev2,prev2logE[m->nbEBands+i]);
+         }
+         Ediff = EXTEND32(logE[c*m->nbEBands+i])-EXTEND32(MIN16(prev1,prev2));
+         Ediff = MAX32(0, Ediff);
+
+#ifdef FIXED_POINT
+         if (Ediff < 16384)
+         {
+            opus_val32 r32 = SHR32(celt_exp2(-EXTRACT16(Ediff)),1);
+            r = 2*MIN16(16383,r32);
+         } else {
+            r = 0;
+         }
+         if (LM==3)
+            r = MULT16_16_Q14(23170, MIN32(23169, r));
+         r = SHR16(MIN16(thresh, r),1);
+         r = SHR32(MULT16_16_Q15(sqrt_1, r),shift);
+#else
+         /* r needs to be multiplied by 2 or 2*sqrt(2) depending on LM because
+            short blocks don't have the same energy as long */
+         r = 2.f*celt_exp2(-Ediff);
+         if (LM==3)
+            r *= 1.41421356f;
+         r = MIN16(thresh, r);
+         r = r*sqrt_1;
+#endif
+         X = X_+c*size+(m->eBands[i]<<LM);
+         for (k=0;k<1<<LM;k++)
+         {
+            /* Detect collapse */
+            if (!(collapse_masks[i*C+c]&1<<k))
+            {
+               /* Fill with noise */
+               for (j=0;j<N0;j++)
+               {
+                  seed = celt_lcg_rand(seed);
+                  X[(j<<LM)+k] = (seed&0x8000 ? r : -r);
+               }
+               renormalize = 1;
+            }
+         }
+         /* We just added some energy, so we need to renormalise */
+         if (renormalize)
+            renormalise_vector(X, N0<<LM, Q15ONE);
+      } while (++c<C);
+   }
+}
+
+static void intensity_stereo(const CELTMode *m, celt_norm *X, celt_norm *Y, const celt_ener *bandE, int bandID, int N)
+{
+   int i = bandID;
+   int j;
+   opus_val16 a1, a2;
+   opus_val16 left, right;
+   opus_val16 norm;
+#ifdef FIXED_POINT
+   int shift = celt_zlog2(MAX32(bandE[i], bandE[i+m->nbEBands]))-13;
+#endif
+   left = VSHR32(bandE[i],shift);
+   right = VSHR32(bandE[i+m->nbEBands],shift);
+   norm = EPSILON + celt_sqrt(EPSILON+MULT16_16(left,left)+MULT16_16(right,right));
+   a1 = DIV32_16(SHL32(EXTEND32(left),14),norm);
+   a2 = DIV32_16(SHL32(EXTEND32(right),14),norm);
+   for (j=0;j<N;j++)
+   {
+      celt_norm r, l;
+      l = X[j];
+      r = Y[j];
+      X[j] = MULT16_16_Q14(a1,l) + MULT16_16_Q14(a2,r);
+      /* Side is not encoded, no need to calculate */
+   }
+}
+
+static void stereo_split(celt_norm *X, celt_norm *Y, int N)
+{
+   int j;
+   for (j=0;j<N;j++)
+   {
+      celt_norm r, l;
+      l = MULT16_16_Q15(QCONST16(.70710678f,15), X[j]);
+      r = MULT16_16_Q15(QCONST16(.70710678f,15), Y[j]);
+      X[j] = l+r;
+      Y[j] = r-l;
+   }
+}
+
+static void stereo_merge(celt_norm *X, celt_norm *Y, opus_val16 mid, int N)
+{
+   int j;
+   opus_val32 xp=0, side=0;
+   opus_val32 El, Er;
+   opus_val16 mid2;
+#ifdef FIXED_POINT
+   int kl, kr;
+#endif
+   opus_val32 t, lgain, rgain;
+
+   /* Compute the norm of X+Y and X-Y as |X|^2 + |Y|^2 +/- sum(xy) */
+   for (j=0;j<N;j++)
+   {
+      xp = MAC16_16(xp, X[j], Y[j]);
+      side = MAC16_16(side, Y[j], Y[j]);
+   }
+   /* Compensating for the mid normalization */
+   xp = MULT16_32_Q15(mid, xp);
+   /* mid and side are in Q15, not Q14 like X and Y */
+   mid2 = SHR32(mid, 1);
+   El = MULT16_16(mid2, mid2) + side - 2*xp;
+   Er = MULT16_16(mid2, mid2) + side + 2*xp;
+   if (Er < QCONST32(6e-4f, 28) || El < QCONST32(6e-4f, 28))
+   {
+      for (j=0;j<N;j++)
+         Y[j] = X[j];
+      return;
+   }
+
+#ifdef FIXED_POINT
+   kl = celt_ilog2(El)>>1;
+   kr = celt_ilog2(Er)>>1;
+#endif
+   t = VSHR32(El, (kl-7)<<1);
+   lgain = celt_rsqrt_norm(t);
+   t = VSHR32(Er, (kr-7)<<1);
+   rgain = celt_rsqrt_norm(t);
+
+#ifdef FIXED_POINT
+   if (kl < 7)
+      kl = 7;
+   if (kr < 7)
+      kr = 7;
+#endif
+
+   for (j=0;j<N;j++)
+   {
+      celt_norm r, l;
+      /* Apply mid scaling (side is already scaled) */
+      l = MULT16_16_Q15(mid, X[j]);
+      r = Y[j];
+      X[j] = EXTRACT16(PSHR32(MULT16_16(lgain, SUB16(l,r)), kl+1));
+      Y[j] = EXTRACT16(PSHR32(MULT16_16(rgain, ADD16(l,r)), kr+1));
+   }
+}
+
+/* Decide whether we should spread the pulses in the current frame */
+int spreading_decision(const CELTMode *m, celt_norm *X, int *average,
+      int last_decision, int *hf_average, int *tapset_decision, int update_hf,
+      int end, int C, int M)
+{
+   int i, c, N0;
+   int sum = 0, nbBands=0;
+   const opus_int16 * OPUS_RESTRICT eBands = m->eBands;
+   int decision;
+   int hf_sum=0;
+
+   celt_assert(end>0);
+
+   N0 = M*m->shortMdctSize;
+
+   if (M*(eBands[end]-eBands[end-1]) <= 8)
+      return SPREAD_NONE;
+   c=0; do {
+      for (i=0;i<end;i++)
+      {
+         int j, N, tmp=0;
+         int tcount[3] = {0,0,0};
+         celt_norm * OPUS_RESTRICT x = X+M*eBands[i]+c*N0;
+         N = M*(eBands[i+1]-eBands[i]);
+         if (N<=8)
+            continue;
+         /* Compute rough CDF of |x[j]| */
+         for (j=0;j<N;j++)
+         {
+            opus_val32 x2N; /* Q13 */
+
+            x2N = MULT16_16(MULT16_16_Q15(x[j], x[j]), N);
+            if (x2N < QCONST16(0.25f,13))
+               tcount[0]++;
+            if (x2N < QCONST16(0.0625f,13))
+               tcount[1]++;
+            if (x2N < QCONST16(0.015625f,13))
+               tcount[2]++;
+         }
+
+         /* Only include four last bands (8 kHz and up) */
+         if (i>m->nbEBands-4)
+            hf_sum += 32*(tcount[1]+tcount[0])/N;
+         tmp = (2*tcount[2] >= N) + (2*tcount[1] >= N) + (2*tcount[0] >= N);
+         sum += tmp*256;
+         nbBands++;
+      }
+   } while (++c<C);
+
+   if (update_hf)
+   {
+      if (hf_sum)
+         hf_sum /= C*(4-m->nbEBands+end);
+      *hf_average = (*hf_average+hf_sum)>>1;
+      hf_sum = *hf_average;
+      if (*tapset_decision==2)
+         hf_sum += 4;
+      else if (*tapset_decision==0)
+         hf_sum -= 4;
+      if (hf_sum > 22)
+         *tapset_decision=2;
+      else if (hf_sum > 18)
+         *tapset_decision=1;
+      else
+         *tapset_decision=0;
+   }
+   /*printf("%d %d %d\n", hf_sum, *hf_average, *tapset_decision);*/
+   celt_assert(nbBands>0); /*M*(eBands[end]-eBands[end-1]) <= 8 assures this*/
+   sum /= nbBands;
+   /* Recursive averaging */
+   sum = (sum+*average)>>1;
+   *average = sum;
+   /* Hysteresis */
+   sum = (3*sum + (((3-last_decision)<<7) + 64) + 2)>>2;
+   if (sum < 80)
+   {
+      decision = SPREAD_AGGRESSIVE;
+   } else if (sum < 256)
+   {
+      decision = SPREAD_NORMAL;
+   } else if (sum < 384)
+   {
+      decision = SPREAD_LIGHT;
+   } else {
+      decision = SPREAD_NONE;
+   }
+#ifdef FUZZING
+   decision = rand()&0x3;
+   *tapset_decision=rand()%3;
+#endif
+   return decision;
+}
+
+#ifdef MEASURE_NORM_MSE
+
+float MSE[30] = {0};
+int nbMSEBands = 0;
+int MSECount[30] = {0};
+
+void dump_norm_mse(void)
+{
+   int i;
+   for (i=0;i<nbMSEBands;i++)
+   {
+      printf ("%g ", MSE[i]/MSECount[i]);
+   }
+   printf ("\n");
+}
+
+void measure_norm_mse(const CELTMode *m, float *X, float *X0, float *bandE, float *bandE0, int M, int N, int C)
+{
+   static int init = 0;
+   int i;
+   if (!init)
+   {
+      atexit(dump_norm_mse);
+      init = 1;
+   }
+   for (i=0;i<m->nbEBands;i++)
+   {
+      int j;
+      int c;
+      float g;
+      if (bandE0[i]<10 || (C==2 && bandE0[i+m->nbEBands]<1))
+         continue;
+      c=0; do {
+         g = bandE[i+c*m->nbEBands]/(1e-15+bandE0[i+c*m->nbEBands]);
+         for (j=M*m->eBands[i];j<M*m->eBands[i+1];j++)
+            MSE[i] += (g*X[j+c*N]-X0[j+c*N])*(g*X[j+c*N]-X0[j+c*N]);
+      } while (++c<C);
+      MSECount[i]+=C;
+   }
+   nbMSEBands = m->nbEBands;
+}
+
+#endif
+
+/* Indexing table for converting from natural Hadamard to ordery Hadamard
+   This is essentially a bit-reversed Gray, on top of which we've added
+   an inversion of the order because we want the DC at the end rather than
+   the beginning. The lines are for N=2, 4, 8, 16 */
+static const int ordery_table[] = {
+       1,  0,
+       3,  0,  2,  1,
+       7,  0,  4,  3,  6,  1,  5,  2,
+      15,  0,  8,  7, 12,  3, 11,  4, 14,  1,  9,  6, 13,  2, 10,  5,
+};
+
+static void deinterleave_hadamard(celt_norm *X, int N0, int stride, int hadamard)
+{
+   int i,j;
+   VARDECL(celt_norm, tmp);
+   int N;
+   SAVE_STACK;
+   N = N0*stride;
+   ALLOC(tmp, N, celt_norm);
+   celt_assert(stride>0);
+   if (hadamard)
+   {
+      const int *ordery = ordery_table+stride-2;
+      for (i=0;i<stride;i++)
+      {
+         for (j=0;j<N0;j++)
+            tmp[ordery[i]*N0+j] = X[j*stride+i];
+      }
+   } else {
+      for (i=0;i<stride;i++)
+         for (j=0;j<N0;j++)
+            tmp[i*N0+j] = X[j*stride+i];
+   }
+   for (j=0;j<N;j++)
+      X[j] = tmp[j];
+   RESTORE_STACK;
+}
+
+static void interleave_hadamard(celt_norm *X, int N0, int stride, int hadamard)
+{
+   int i,j;
+   VARDECL(celt_norm, tmp);
+   int N;
+   SAVE_STACK;
+   N = N0*stride;
+   ALLOC(tmp, N, celt_norm);
+   if (hadamard)
+   {
+      const int *ordery = ordery_table+stride-2;
+      for (i=0;i<stride;i++)
+         for (j=0;j<N0;j++)
+            tmp[j*stride+i] = X[ordery[i]*N0+j];
+   } else {
+      for (i=0;i<stride;i++)
+         for (j=0;j<N0;j++)
+            tmp[j*stride+i] = X[i*N0+j];
+   }
+   for (j=0;j<N;j++)
+      X[j] = tmp[j];
+   RESTORE_STACK;
+}
+
+void haar1(celt_norm *X, int N0, int stride)
+{
+   int i, j;
+   N0 >>= 1;
+   for (i=0;i<stride;i++)
+      for (j=0;j<N0;j++)
+      {
+         celt_norm tmp1, tmp2;
+         tmp1 = MULT16_16_Q15(QCONST16(.70710678f,15), X[stride*2*j+i]);
+         tmp2 = MULT16_16_Q15(QCONST16(.70710678f,15), X[stride*(2*j+1)+i]);
+         X[stride*2*j+i] = tmp1 + tmp2;
+         X[stride*(2*j+1)+i] = tmp1 - tmp2;
+      }
+}
+
+static int compute_qn(int N, int b, int offset, int pulse_cap, int stereo)
+{
+   static const opus_int16 exp2_table8[8] =
+      {16384, 17866, 19483, 21247, 23170, 25267, 27554, 30048};
+   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 = IMIN(b-pulse_cap-(4<<BITRES), (b+N2*offset)/N2);
+
+   qb = IMIN(8<<BITRES, qb);
+
+   if (qb<(1<<BITRES>>1)) {
+      qn = 1;
+   } else {
+      qn = exp2_table8[qb&0x7]>>(14-(qb>>BITRES));
+      qn = (qn+1)>>1<<1;
+   }
+   celt_assert(qn <= 256);
+   return qn;
+}
+
+/* This function is responsible for encoding and decoding a band for both
+   the mono and stereo case. Even in the mono case, it can split the band
+   in two and transmit the energy difference with the two half-bands. It
+   can be called recursively so bands can end up being split in 8 parts. */
+static unsigned quant_band(int encode, const CELTMode *m, int i, celt_norm *X, celt_norm *Y,
+      int N, int b, int spread, int B, int intensity, int tf_change, celt_norm *lowband, ec_ctx *ec,
+      opus_int32 *remaining_bits, int LM, celt_norm *lowband_out, const celt_ener *bandE, int level,
+      opus_uint32 *seed, opus_val16 gain, celt_norm *lowband_scratch, int fill)
+{
+   const unsigned char *cache;
+   int q;
+   int curr_bits;
+   int stereo, split;
+   int imid=0, iside=0;
+   int N0=N;
+   int N_B=N;
+   int N_B0;
+   int B0=B;
+   int time_divide=0;
+   int recombine=0;
+   int inv = 0;
+   opus_val16 mid=0, side=0;
+   int longBlocks;
+   unsigned cm=0;
+#ifdef RESYNTH
+   int resynth = 1;
+#else
+   int resynth = !encode;
+#endif
+
+   longBlocks = B0==1;
+
+   N_B /= B;
+   N_B0 = N_B;
+
+   split = stereo = Y != NULL;
+
+   /* Special case for one sample */
+   if (N==1)
+   {
+      int c;
+      celt_norm *x = X;
+      c=0; do {
+         int sign=0;
+         if (*remaining_bits>=1<<BITRES)
+         {
+            if (encode)
+            {
+               sign = x[0]<0;
+               ec_enc_bits(ec, sign, 1);
+            } else {
+               sign = ec_dec_bits(ec, 1);
+            }
+            *remaining_bits -= 1<<BITRES;
+            b-=1<<BITRES;
+         }
+         if (resynth)
+            x[0] = sign ? -NORM_SCALING : NORM_SCALING;
+         x = Y;
+      } while (++c<1+stereo);
+      if (lowband_out)
+         lowband_out[0] = SHR16(X[0],4);
+      return 1;
+   }
+
+   if (!stereo && level == 0)
+   {
+      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))
+      {
+         int j;
+         for (j=0;j<N;j++)
+            lowband_scratch[j] = lowband[j];
+         lowband = lowband_scratch;
+      }
+
+      for (k=0;k<recombine;k++)
+      {
+         static const unsigned char bit_interleave_table[16]={
+           0,1,1,1,2,3,3,3,2,3,3,3,2,3,3,3
+         };
+         if (encode)
+            haar1(X, N>>k, 1<<k);
+         if (lowband)
+            haar1(lowband, N>>k, 1<<k);
+         fill = bit_interleave_table[fill&0xF]|bit_interleave_table[fill>>4]<<2;
+      }
+      B>>=recombine;
+      N_B<<=recombine;
+
+      /* Increasing the time resolution */
+      while ((N_B&1) == 0 && tf_change<0)
+      {
+         if (encode)
+            haar1(X, N_B, B);
+         if (lowband)
+            haar1(lowband, N_B, B);
+         fill |= fill<<B;
+         B <<= 1;
+         N_B >>= 1;
+         time_divide++;
+         tf_change++;
+      }
+      B0=B;
+      N_B0 = N_B;
+
+      /* Reorganize the samples in time order instead of frequency order */
+      if (B0>1)
+      {
+         if (encode)
+            deinterleave_hadamard(X, N_B>>recombine, B0<<recombine, longBlocks);
+         if (lowband)
+            deinterleave_hadamard(lowband, N_B>>recombine, B0<<recombine, longBlocks);
+      }
+   }
+
+   /* If we need 1.5 more bit than we can produce, split the band in two. */
+   cache = m->cache.bits + m->cache.index[(LM+1)*m->nbEBands+i];
+   if (!stereo && LM != -1 && b > cache[cache[0]]+12 && N>2)
+   {
+      N >>= 1;
+      Y = X+N;
+      split = 1;
+      LM -= 1;
+      if (B==1)
+         fill = (fill&1)|(fill<<1);
+      B = (B+1)>>1;
+   }
+
+   if (split)
+   {
+      int qn;
+      int itheta=0;
+      int mbits, sbits, delta;
+      int qalloc;
+      int pulse_cap;
+      int offset;
+      int orig_fill;
+      opus_int32 tell;
+
+      /* Decide on the resolution to give to the split parameter theta */
+      pulse_cap = m->logN[i]+LM*(1<<BITRES);
+      offset = (pulse_cap>>1) - (stereo&&N==2 ? QTHETA_OFFSET_TWOPHASE : QTHETA_OFFSET);
+      qn = compute_qn(N, b, offset, pulse_cap, stereo);
+      if (stereo && i>=intensity)
+         qn = 1;
+      if (encode)
+      {
+         /* theta is the atan() of the ratio between the (normalized)
+            side and mid. With just that parameter, we can re-scale both
+            mid and side because we know that 1) they have unit norm and
+            2) they are orthogonal. */
+         itheta = stereo_itheta(X, Y, stereo, N);
+      }
+      tell = ec_tell_frac(ec);
+      if (qn!=1)
+      {
+         if (encode)
+            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 (stereo && N>2)
+         {
+            int p0 = 3;
+            int x = itheta;
+            int x0 = qn/2;
+            int ft = p0*(x0+1) + x0;
+            /* Use a probability of p0 up to itheta=8192 and then use 1 after */
+            if (encode)
+            {
+               ec_encode(ec,x<=x0?p0*x:(x-1-x0)+(x0+1)*p0,x<=x0?p0*(x+1):(x-x0)+(x0+1)*p0,ft);
+            } else {
+               int fs;
+               fs=ec_decode(ec,ft);
+               if (fs<(x0+1)*p0)
+                  x=fs/p0;
+               else
+                  x=x0+1+(fs-(x0+1)*p0);
+               ec_dec_update(ec,x<=x0?p0*x:(x-1-x0)+(x0+1)*p0,x<=x0?p0*(x+1):(x-x0)+(x0+1)*p0,ft);
+               itheta = x;
+            }
+         } else if (B0>1 || stereo) {
+            /* Uniform pdf */
+            if (encode)
+               ec_enc_uint(ec, itheta, qn+1);
+            else
+               itheta = ec_dec_uint(ec, qn+1);
+         } else {
+            int fs=1, ft;
+            ft = ((qn>>1)+1)*((qn>>1)+1);
+            if (encode)
+            {
+               int fl;
+
+               fs = itheta <= (qn>>1) ? itheta + 1 : qn + 1 - itheta;
+               fl = itheta <= (qn>>1) ? itheta*(itheta + 1)>>1 :
+                ft - ((qn + 1 - itheta)*(qn + 2 - itheta)>>1);
+
+               ec_encode(ec, fl, fl+fs, ft);
+            } else {
+               /* Triangular pdf */
+               int fl=0;
+               int fm;
+               fm = ec_decode(ec, ft);
+
+               if (fm < ((qn>>1)*((qn>>1) + 1)>>1))
+               {
+                  itheta = (isqrt32(8*(opus_uint32)fm + 1) - 1)>>1;
+                  fs = itheta + 1;
+                  fl = itheta*(itheta + 1)>>1;
+               }
+               else
+               {
+                  itheta = (2*(qn + 1)
+                   - isqrt32(8*(opus_uint32)(ft - fm - 1) + 1))>>1;
+                  fs = qn + 1 - itheta;
+                  fl = ft - ((qn + 1 - itheta)*(qn + 2 - itheta)>>1);
+               }
+
+               ec_dec_update(ec, fl, fl+fs, ft);
+            }
+         }
+         itheta = (opus_int32)itheta*16384/qn;
+         if (encode && stereo)
+         {
+            if (itheta==0)
+               intensity_stereo(m, X, Y, bandE, i, N);
+            else
+               stereo_split(X, Y, N);
+         }
+         /* NOTE: Renormalising X and Y *may* help fixed-point a bit at very high rate.
+                  Let's do that at higher complexity */
+      } else if (stereo) {
+         if (encode)
+         {
+            inv = itheta > 8192;
+            if (inv)
+            {
+               int j;
+               for (j=0;j<N;j++)
+                  Y[j] = -Y[j];
+            }
+            intensity_stereo(m, X, Y, bandE, i, N);
+         }
+         if (b>2<<BITRES && *remaining_bits > 2<<BITRES)
+         {
+            if (encode)
+               ec_enc_bit_logp(ec, inv, 2);
+            else
+               inv = ec_dec_bit_logp(ec, 2);
+         } else
+            inv = 0;
+         itheta = 0;
+      }
+      qalloc = ec_tell_frac(ec) - tell;
+      b -= qalloc;
+
+      orig_fill = fill;
+      if (itheta == 0)
+      {
+         imid = 32767;
+         iside = 0;
+         fill &= (1<<B)-1;
+         delta = -16384;
+      } else if (itheta == 16384)
+      {
+         imid = 0;
+         iside = 32767;
+         fill &= ((1<<B)-1)<<B;
+         delta = 16384;
+      } else {
+         imid = bitexact_cos((opus_int16)itheta);
+         iside = bitexact_cos((opus_int16)(16384-itheta));
+         /* This is the mid vs side allocation that minimizes squared error
+            in that band. */
+         delta = FRAC_MUL16((N-1)<<7,bitexact_log2tan(iside,imid));
+      }
+
+#ifdef FIXED_POINT
+      mid = imid;
+      side = iside;
+#else
+      mid = (1.f/32768)*imid;
+      side = (1.f/32768)*iside;
+#endif
+
+      /* 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;
+         celt_norm *x2, *y2;
+         mbits = b;
+         sbits = 0;
+         /* Only need one bit for the side */
+         if (itheta != 0 && itheta != 16384)
+            sbits = 1<<BITRES;
+         mbits -= sbits;
+         c = itheta > 8192;
+         *remaining_bits -= qalloc+sbits;
+
+         x2 = c ? Y : X;
+         y2 = c ? X : Y;
+         if (sbits)
+         {
+            if (encode)
+            {
+               /* Here we only need to encode a sign for the side */
+               sign = x2[0]*y2[1] - x2[1]*y2[0] < 0;
+               ec_enc_bits(ec, sign, 1);
+            } else {
+               sign = ec_dec_bits(ec, 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 = quant_band(encode, m, i, x2, NULL, N, mbits, spread, B, intensity, tf_change, lowband, ec, remaining_bits, LM, lowband_out, NULL, level, seed, 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];
+         if (resynth)
+         {
+            celt_norm tmp;
+            X[0] = MULT16_16_Q15(mid, X[0]);
+            X[1] = MULT16_16_Q15(mid, X[1]);
+            Y[0] = MULT16_16_Q15(side, Y[0]);
+            Y[1] = MULT16_16_Q15(side, Y[1]);
+            tmp = X[0];
+            X[0] = SUB16(tmp,Y[0]);
+            Y[0] = ADD16(tmp,Y[0]);
+            tmp = X[1];
+            X[1] = SUB16(tmp,Y[1]);
+            Y[1] = ADD16(tmp,Y[1]);
+         }
+      } else {
+         /* "Normal" split code */
+         celt_norm *next_lowband2=NULL;
+         celt_norm *next_lowband_out1=NULL;
+         int next_level=0;
+         opus_int32 rebalance;
+
+         /* 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-LM);
+            else
+               /* Corresponds to a forward-masking slope of 1.5 dB per 10 ms */
+               delta = IMIN(0, delta + (N<<BITRES>>(5-LM)));
+         }
+         mbits = IMAX(0, IMIN(b, (b-delta)/2));
+         sbits = b-mbits;
+         *remaining_bits -= 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 = *remaining_bits;
+         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 = quant_band(encode, m, i, X, NULL, N, mbits, spread, B, intensity, tf_change,
+                  lowband, ec, remaining_bits, LM, next_lowband_out1,
+                  NULL, next_level, seed, stereo ? Q15ONE : MULT16_16_P15(gain,mid), lowband_scratch, fill);
+            rebalance = mbits - (rebalance-*remaining_bits);
+            if (rebalance > 3<<BITRES && itheta!=0)
+               sbits += rebalance - (3<<BITRES);
+
+            /* For a stereo split, the high bits of fill are always zero, so no
+               folding will be done to the side. */
+            cm |= quant_band(encode, m, i, Y, NULL, N, sbits, spread, B, intensity, tf_change,
+                  next_lowband2, ec, remaining_bits, LM, NULL,
+                  NULL, next_level, seed, MULT16_16_P15(gain,side), NULL, fill>>B)<<((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 = quant_band(encode, m, i, Y, NULL, N, sbits, spread, B, intensity, tf_change,
+                  next_lowband2, ec, remaining_bits, LM, NULL,
+                  NULL, next_level, seed, MULT16_16_P15(gain,side), NULL, fill>>B)<<((B0>>1)&(stereo-1));
+            rebalance = sbits - (rebalance-*remaining_bits);
+            if (rebalance > 3<<BITRES && itheta!=16384)
+               mbits += rebalance - (3<<BITRES);
+            /* In stereo mode, we do not apply a scaling to the mid because we need the normalized
+               mid for folding later */
+            cm |= quant_band(encode, m, i, X, NULL, N, mbits, spread, B, intensity, tf_change,
+                  lowband, ec, remaining_bits, LM, next_lowband_out1,
+                  NULL, next_level, seed, stereo ? Q15ONE : MULT16_16_P15(gain,mid), lowband_scratch, fill);
+         }
+      }
+
+   } else {
+      /* This is the basic no-split case */
+      q = bits2pulses(m, i, LM, b);
+      curr_bits = pulses2bits(m, i, LM, q);
+      *remaining_bits -= curr_bits;
+
+      /* Ensures we can never bust the budget */
+      while (*remaining_bits < 0 && q > 0)
+      {
+         *remaining_bits += curr_bits;
+         q--;
+         curr_bits = pulses2bits(m, i, LM, q);
+         *remaining_bits -= curr_bits;
+      }
+
+      if (q!=0)
+      {
+         int K = get_pulses(q);
+
+         /* Finally do the actual quantization */
+         if (encode)
+         {
+            cm = alg_quant(X, N, K, spread, B, ec
+#ifdef RESYNTH
+                 , gain
+#endif
+                 );
+         } else {
+            cm = alg_unquant(X, N, K, spread, B, ec, gain);
+         }
+      } else {
+         /* If there's no pulse, fill the band anyway */
+         int j;
+         if (resynth)
+         {
+            unsigned cm_mask;
+            /*B can be as large as 16, so this shift might overflow an int on a
+               16-bit platform; use a long to get defined behavior.*/
+            cm_mask = (unsigned)(1UL<<B)-1;
+            fill &= cm_mask;
+            if (!fill)
+            {
+               for (j=0;j<N;j++)
+                  X[j] = 0;
+            } else {
+               if (lowband == NULL)
+               {
+                  /* Noise */
+                  for (j=0;j<N;j++)
+                  {
+                     *seed = celt_lcg_rand(*seed);
+                     X[j] = (celt_norm)((opus_int32)*seed>>20);
+                  }
+                  cm = cm_mask;
+               } else {
+                  /* Folded spectrum */
+                  for (j=0;j<N;j++)
+                  {
+                     opus_val16 tmp;
+                     *seed = celt_lcg_rand(*seed);
+                     /* About 48 dB below the "normal" folding level */
+                     tmp = QCONST16(1.0f/256, 10);
+                     tmp = (*seed)&0x8000 ? tmp : -tmp;
+                     X[j] = lowband[j]+tmp;
+                  }
+                  cm = fill;
+               }
+               renormalise_vector(X, N, gain);
+            }
+         }
+      }
+   }
+
+   /* This code is used by the decoder and by the resynthesis-enabled encoder */
+   if (resynth)
+   {
+      if (stereo)
+      {
+         if (N!=2)
+            stereo_merge(X, Y, mid, N);
+         if (inv)
+         {
+            int j;
+            for (j=0;j<N;j++)
+               Y[j] = -Y[j];
+         }
+      } else if (level == 0)
+      {
+         int k;
+
+         /* Undo the sample reorganization going from time order to frequency order */
+         if (B0>1)
+            interleave_hadamard(X, N_B>>recombine, B0<<recombine, longBlocks);
+
+         /* Undo time-freq changes that we did earlier */
+         N_B = N_B0;
+         B = B0;
+         for (k=0;k<time_divide;k++)
+         {
+            B >>= 1;
+            N_B <<= 1;
+            cm |= cm>>B;
+            haar1(X, N_B, B);
+         }
+
+         for (k=0;k<recombine;k++)
+         {
+            static const unsigned char bit_deinterleave_table[16]={
+              0x00,0x03,0x0C,0x0F,0x30,0x33,0x3C,0x3F,
+              0xC0,0xC3,0xCC,0xCF,0xF0,0xF3,0xFC,0xFF
+            };
+            cm = bit_deinterleave_table[cm];
+            haar1(X, N0>>k, 1<<k);
+         }
+         B<<=recombine;
+
+         /* Scale output for later folding */
+         if (lowband_out)
+         {
+            int j;
+            opus_val16 n;
+            n = celt_sqrt(SHL32(EXTEND32(N0),22));
+            for (j=0;j<N0;j++)
+               lowband_out[j] = MULT16_16_Q15(n,X[j]);
+         }
+         cm &= (1<<B)-1;
+      }
+   }
+   return cm;
+}
+
+void quant_all_bands(int encode, const CELTMode *m, int start, int end,
+      celt_norm *X_, celt_norm *Y_, unsigned char *collapse_masks, const celt_ener *bandE, int *pulses,
+      int shortBlocks, int spread, int dual_stereo, int intensity, int *tf_res,
+      opus_int32 total_bits, opus_int32 balance, ec_ctx *ec, int LM, int codedBands, opus_uint32 *seed)
+{
+   int i;
+   opus_int32 remaining_bits;
+   const opus_int16 * OPUS_RESTRICT eBands = m->eBands;
+   celt_norm * OPUS_RESTRICT norm, * OPUS_RESTRICT norm2;
+   VARDECL(celt_norm, _norm);
+   VARDECL(celt_norm, lowband_scratch);
+   int B;
+   int M;
+   int lowband_offset;
+   int update_lowband = 1;
+   int C = Y_ != NULL ? 2 : 1;
+#ifdef RESYNTH
+   int resynth = 1;
+#else
+   int resynth = !encode;
+#endif
+   SAVE_STACK;
+
+   M = 1<<LM;
+   B = shortBlocks ? M : 1;
+   ALLOC(_norm, C*M*eBands[m->nbEBands], celt_norm);
+   ALLOC(lowband_scratch, M*(eBands[m->nbEBands]-eBands[m->nbEBands-1]), celt_norm);
+   norm = _norm;
+   norm2 = norm + M*eBands[m->nbEBands];
+
+   lowband_offset = 0;
+   for (i=start;i<end;i++)
+   {
+      opus_int32 tell;
+      int b;
+      int N;
+      opus_int32 curr_balance;
+      int effective_lowband=-1;
+      celt_norm * OPUS_RESTRICT X, * OPUS_RESTRICT Y;
+      int tf_change=0;
+      unsigned x_cm;
+      unsigned y_cm;
+
+      X = X_+M*eBands[i];
+      if (Y_!=NULL)
+         Y = Y_+M*eBands[i];
+      else
+         Y = NULL;
+      N = M*eBands[i+1]-M*eBands[i];
+      tell = ec_tell_frac(ec);
+
+      /* Compute how many bits we want to allocate to this band */
+      if (i != start)
+         balance -= tell;
+      remaining_bits = total_bits-tell-1;
+      if (i <= codedBands-1)
+      {
+         curr_balance = balance / IMIN(3, codedBands-i);
+         b = IMAX(0, IMIN(16383, IMIN(remaining_bits+1,pulses[i]+curr_balance)));
+      } else {
+         b = 0;
+      }
+
+      if (resynth && M*eBands[i]-N >= M*eBands[start] && (update_lowband || lowband_offset==0))
+            lowband_offset = i;
+
+      tf_change = tf_res[i];
+      if (i>=m->effEBands)
+      {
+         X=norm;
+         if (Y_!=NULL)
+            Y = norm;
+      }
+
+      /* Get a conservative estimate of the collapse_mask's for the bands we're
+          going to be folding from. */
+      if (lowband_offset != 0 && (spread!=SPREAD_AGGRESSIVE || B>1 || tf_change<0))
+      {
+         int fold_start;
+         int fold_end;
+         int fold_i;
+         /* This ensures we never repeat spectral content within one band */
+         effective_lowband = IMAX(M*eBands[start], M*eBands[lowband_offset]-N);
+         fold_start = lowband_offset;
+         while(M*eBands[--fold_start] > effective_lowband);
+         fold_end = lowband_offset-1;
+         while(M*eBands[++fold_end] < effective_lowband+N);
+         x_cm = y_cm = 0;
+         fold_i = fold_start; do {
+           x_cm |= collapse_masks[fold_i*C+0];
+           y_cm |= collapse_masks[fold_i*C+C-1];
+         } while (++fold_i<fold_end);
+      }
+      /* Otherwise, we'll be using the LCG to fold, so all blocks will (almost
+          always) be non-zero.*/
+      else
+         x_cm = y_cm = (1<<B)-1;
+
+      if (dual_stereo && i==intensity)
+      {
+         int j;
+
+         /* Switch off dual stereo to do intensity */
+         dual_stereo = 0;
+         if (resynth)
+            for (j=M*eBands[start];j<M*eBands[i];j++)
+               norm[j] = HALF32(norm[j]+norm2[j]);
+      }
+      if (dual_stereo)
+      {
+         x_cm = quant_band(encode, m, i, X, NULL, N, b/2, spread, B, intensity, tf_change,
+               effective_lowband != -1 ? norm+effective_lowband : NULL, ec, &remaining_bits, LM,
+               norm+M*eBands[i], bandE, 0, seed, Q15ONE, lowband_scratch, x_cm);
+         y_cm = quant_band(encode, m, i, Y, NULL, N, b/2, spread, B, intensity, tf_change,
+               effective_lowband != -1 ? norm2+effective_lowband : NULL, ec, &remaining_bits, LM,
+               norm2+M*eBands[i], bandE, 0, seed, Q15ONE, lowband_scratch, y_cm);
+      } else {
+         x_cm = quant_band(encode, m, i, X, Y, N, b, spread, B, intensity, tf_change,
+               effective_lowband != -1 ? norm+effective_lowband : NULL, ec, &remaining_bits, LM,
+               norm+M*eBands[i], bandE, 0, seed, Q15ONE, lowband_scratch, x_cm|y_cm);
+         y_cm = x_cm;
+      }
+      collapse_masks[i*C+0] = (unsigned char)x_cm;
+      collapse_masks[i*C+C-1] = (unsigned char)y_cm;
+      balance += pulses[i] + tell;
+
+      /* Update the folding position only as long as we have 1 bit/sample depth */
+      update_lowband = b>(N<<BITRES);
+   }
+   RESTORE_STACK;
+}
+