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pack.c

////////////////////////////////////////////////////////////////////////////
//                     **** WAVPACK ****                      //
//              Hybrid Lossless Wavefile Compressor                 //
//          Copyright (c) 1998 - 2005 Conifer Software.             //
//                    All Rights Reserved.                    //
//      Distributed under the BSD Software License (see license.txt)      //
////////////////////////////////////////////////////////////////////////////

// pack.c

// This module actually handles the compression of the audio data, except for
// the entropy coding which is handled by the words? modules. For efficiency,
// the conversion is isolated to tight loops that handle an entire buffer.

#include "wavpack.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>

// This flag provides faster encoding speed at the expense of more code. The
// improvement applies to 16-bit stereo lossless only.

#define FAST_ENCODE

#ifdef DEBUG_ALLOC
#define malloc malloc_db
#define realloc realloc_db
#define free free_db
void *malloc_db (uint32_t size);
void *realloc_db (void *ptr, uint32_t size);
void free_db (void *ptr);
int32_t dump_alloc (void);
#endif

//////////////////////////////// local tables ///////////////////////////////

// These two tables specify the characteristics of the decorrelation filters.
// Each term represents one layer of the sequential filter, where positive
// values indicate the relative sample involved from the same channel (1=prev),
// 17 & 18 are special functions using the previous 2 samples, and negative
// values indicate cross channel decorrelation (in stereo only).

const signed char default_terms [] = { 18,18,2,3,-2,0 };
const signed char high_terms [] = { 18,18,2,3,-2,18,2,4,7,5,3,6,8,-1,18,2,0 };
const signed char fast_terms [] = { 17,17,0 };

///////////////////////////// executable code ////////////////////////////////

// This function initializes everything required to pack WavPack bitstreams
// and must be called BEFORE any other function in this module.

void pack_init (WavpackContext *wpc)
{
    WavpackStream *wps = wpc->streams [wpc->current_stream];
    uint32_t flags = wps->wphdr.flags;

    wps->sample_index = 0;
    wps->delta_decay = 2.0;
    CLEAR (wps->decorr_passes);
    CLEAR (wps->dc);

    if (wpc->config.flags & CONFIG_AUTO_SHAPING)
      wps->dc.shaping_acc [0] = wps->dc.shaping_acc [1] =
          (wpc->config.sample_rate < 64000 || (wps->wphdr.flags & CROSS_DECORR)) ? -512L << 16 : 1024L << 16;
    else {
      int32_t weight = (int32_t) floor (wpc->config.shaping_weight * 1024.0 + 0.5);

      if (weight <= -1000)
          weight = -1000;

      wps->dc.shaping_acc [0] = wps->dc.shaping_acc [1] = weight << 16;
    }

    init_words (wps);
}

// Allocate room for and copy the decorrelation terms from the decorr_passes
// array into the specified metadata structure. Both the actual term id and
// the delta are packed into single characters.

void write_decorr_terms (WavpackStream *wps, WavpackMetadata *wpmd)
{
    int tcount = wps->num_terms;
    struct decorr_pass *dpp;
    char *byteptr;

    byteptr = wpmd->data = malloc (tcount + 1);
    wpmd->id = ID_DECORR_TERMS;

    for (dpp = wps->decorr_passes; tcount--; ++dpp)
      *byteptr++ = ((dpp->term + 5) & 0x1f) | ((dpp->delta << 5) & 0xe0);

    wpmd->byte_length = byteptr - (char *) wpmd->data;
}

// Allocate room for and copy the decorrelation term weights from the
// decorr_passes array into the specified metadata structure. The weights
// range +/-1024, but are rounded and truncated to fit in signed chars for
// metadata storage. Weights are separate for the two channels

void write_decorr_weights (WavpackStream *wps, WavpackMetadata *wpmd)
{
    struct decorr_pass *dpp = wps->decorr_passes;
    int tcount = wps->num_terms, i;
    char *byteptr;

    byteptr = wpmd->data = malloc ((tcount * 2) + 1);
    wpmd->id = ID_DECORR_WEIGHTS;

    for (i = wps->num_terms - 1; i >= 0; --i)
      if (store_weight (dpp [i].weight_A) ||
          (!(wps->wphdr.flags & MONO_DATA) && store_weight (dpp [i].weight_B)))
            break;

    tcount = i + 1;

    for (i = 0; i < wps->num_terms; ++i) {
      if (i < tcount) {
          dpp [i].weight_A = restore_weight (*byteptr++ = store_weight (dpp [i].weight_A));

          if (!(wps->wphdr.flags & MONO_DATA))
            dpp [i].weight_B = restore_weight (*byteptr++ = store_weight (dpp [i].weight_B));
      }
      else
          dpp [i].weight_A = dpp [i].weight_B = 0;
    }

    wpmd->byte_length = byteptr - (char *) wpmd->data;
}

// Allocate room for and copy the decorrelation samples from the decorr_passes
// array into the specified metadata structure. The samples are signed 32-bit
// values, but are converted to signed log2 values for storage in metadata.
// Values are stored for both channels and are specified from the first term
// with unspecified samples set to zero. The number of samples stored varies
// with the actual term value, so those must obviously be specified before
// these in the metadata list. Any number of terms can have their samples
// specified from no terms to all the terms, however I have found that
// sending more than the first term's samples is a waste. The "wcount"
// variable can be set to the number of terms to have their samples stored.

void write_decorr_samples (WavpackStream *wps, WavpackMetadata *wpmd)
{
    int tcount = wps->num_terms, wcount = 1, temp;
    struct decorr_pass *dpp;
    uchar *byteptr;

    byteptr = wpmd->data = malloc (256);
    wpmd->id = ID_DECORR_SAMPLES;

    for (dpp = wps->decorr_passes; tcount--; ++dpp)
      if (wcount) {
          if (dpp->term > MAX_TERM) {
            dpp->samples_A [0] = exp2s (temp = log2s (dpp->samples_A [0]));
            *byteptr++ = temp;
            *byteptr++ = temp >> 8;
            dpp->samples_A [1] = exp2s (temp = log2s (dpp->samples_A [1]));
            *byteptr++ = temp;
            *byteptr++ = temp >> 8;

            if (!(wps->wphdr.flags & MONO_DATA)) {
                dpp->samples_B [0] = exp2s (temp = log2s (dpp->samples_B [0]));
                *byteptr++ = temp;
                *byteptr++ = temp >> 8;
                dpp->samples_B [1] = exp2s (temp = log2s (dpp->samples_B [1]));
                *byteptr++ = temp;
                *byteptr++ = temp >> 8;
            }
          }
          else if (dpp->term < 0) {
            dpp->samples_A [0] = exp2s (temp = log2s (dpp->samples_A [0]));
            *byteptr++ = temp;
            *byteptr++ = temp >> 8;
            dpp->samples_B [0] = exp2s (temp = log2s (dpp->samples_B [0]));
            *byteptr++ = temp;
            *byteptr++ = temp >> 8;
          }
          else {
            int m = 0, cnt = dpp->term;

            while (cnt--) {
                dpp->samples_A [m] = exp2s (temp = log2s (dpp->samples_A [m]));
                *byteptr++ = temp;
                *byteptr++ = temp >> 8;

                if (!(wps->wphdr.flags & MONO_DATA)) {
                  dpp->samples_B [m] = exp2s (temp = log2s (dpp->samples_B [m]));
                  *byteptr++ = temp;
                  *byteptr++ = temp >> 8;
                }

                m++;
            }
          }

          wcount--;
      }
      else {
          CLEAR (dpp->samples_A);
          CLEAR (dpp->samples_B);
      }

    wpmd->byte_length = byteptr - (uchar *) wpmd->data;
}

// Allocate room for and copy the noise shaping info into the specified
// metadata structure. These would normally be written to the
// "correction" file and are used for lossless reconstruction of
// hybrid data. The "delta" parameter is not yet used in encoding as it
// will be part of the "quality" mode.

void write_shaping_info (WavpackStream *wps, WavpackMetadata *wpmd)
{
    char *byteptr;
    int temp;

    byteptr = wpmd->data = malloc (12);
    wpmd->id = ID_SHAPING_WEIGHTS;

    wps->dc.error [0] = exp2s (temp = log2s (wps->dc.error [0]));
    *byteptr++ = temp;
    *byteptr++ = temp >> 8;
    wps->dc.shaping_acc [0] = exp2s (temp = log2s (wps->dc.shaping_acc [0]));
    *byteptr++ = temp;
    *byteptr++ = temp >> 8;

    if (!(wps->wphdr.flags & MONO_DATA)) {
      wps->dc.error [1] = exp2s (temp = log2s (wps->dc.error [1]));
      *byteptr++ = temp;
      *byteptr++ = temp >> 8;
      wps->dc.shaping_acc [1] = exp2s (temp = log2s (wps->dc.shaping_acc [1]));
      *byteptr++ = temp;
      *byteptr++ = temp >> 8;
    }

    if (wps->dc.shaping_delta [0] | wps->dc.shaping_delta [1]) {
      wps->dc.shaping_delta [0] = exp2s (temp = log2s (wps->dc.shaping_delta [0]));
      *byteptr++ = temp;
      *byteptr++ = temp >> 8;

      if (!(wps->wphdr.flags & MONO_DATA)) {
          wps->dc.shaping_delta [1] = exp2s (temp = log2s (wps->dc.shaping_delta [1]));
          *byteptr++ = temp;
          *byteptr++ = temp >> 8;
      }
    }

    wpmd->byte_length = byteptr - (char *) wpmd->data;
}

// Allocate room for and copy the int32 data values into the specified
// metadata structure. This data is used for integer data that has more
// than 24 bits of magnitude or, in some cases, it's used to eliminate
// redundant bits from any audio stream.

void write_int32_info (WavpackStream *wps, WavpackMetadata *wpmd)
{
    char *byteptr;

    byteptr = wpmd->data = malloc (4);
    wpmd->id = ID_INT32_INFO;
    *byteptr++ = wps->int32_sent_bits;
    *byteptr++ = wps->int32_zeros;
    *byteptr++ = wps->int32_ones;
    *byteptr++ = wps->int32_dups;
    wpmd->byte_length = byteptr - (char *) wpmd->data;
}

// Allocate room for and copy the multichannel information into the specified
// metadata structure. The first byte is the total number of channels and the
// following bytes represent the channel_mask as described for Microsoft
// WAVEFORMATEX.

void write_channel_info (WavpackContext *wpc, WavpackMetadata *wpmd)
{
    uint32_t mask = wpc->config.channel_mask;
    char *byteptr;

    byteptr = wpmd->data = malloc (4);
    wpmd->id = ID_CHANNEL_INFO;
    *byteptr++ = wpc->config.num_channels;

    while (mask) {
      *byteptr++ = mask;
      mask >>= 8;
    }

    wpmd->byte_length = byteptr - (char *) wpmd->data;
}

// Allocate room for and copy the configuration information into the specified
// metadata structure. Currently, we just store the upper 3 bytes of
// config.flags and only in the first block of audio data. Note that this is
// for informational purposes not required for playback or decoding (like
// whether high or fast mode was specified).

void write_config_info (WavpackContext *wpc, WavpackMetadata *wpmd)
{
    char *byteptr;

    byteptr = wpmd->data = malloc (4);
    wpmd->id = ID_CONFIG_BLOCK;
    *byteptr++ = (char) (wpc->config.flags >> 8);
    *byteptr++ = (char) (wpc->config.flags >> 16);
    *byteptr++ = (char) (wpc->config.flags >> 24);
    wpmd->byte_length = byteptr - (char *) wpmd->data;
}

// Allocate room for and copy the non-standard sampling rateinto the specified
// metadata structure. We just store the lower 3 bytes of the sampling rate.
// Note that this would only be used when the sampling rate was not included
// in the table of 15 "standard" values.

void write_sample_rate (WavpackContext *wpc, WavpackMetadata *wpmd)

{
    char *byteptr;

    byteptr = wpmd->data = malloc (4);
    wpmd->id = ID_SAMPLE_RATE;
    *byteptr++ = (char) (wpc->config.sample_rate);
    *byteptr++ = (char) (wpc->config.sample_rate >> 8);
    *byteptr++ = (char) (wpc->config.sample_rate >> 16);
    wpmd->byte_length = byteptr - (char *) wpmd->data;
}

// Pack an entire block of samples (either mono or stereo) into a completed
// WavPack block. This function is actually a shell for pack_samples() and
// performs tasks like handling any shift required by the format, preprocessing
// of floating point data or integer data over 24 bits wide, and implementing
// the "extra" mode (via the extra?.c modules). It is assumed that there is
// sufficient space for the completed block at "wps->blockbuff" and that
// "wps->blockend" points to the end of the available space. A return value of
// FALSE indicates an error.

static int scan_int32_data (WavpackStream *wps, int32_t *values, int32_t num_values);
static void scan_int32_quick (WavpackStream *wps, int32_t *values, int32_t num_values);
static void send_int32_data (WavpackStream *wps, int32_t *values, int32_t num_values);
static int pack_samples (WavpackContext *wpc, int32_t *buffer);

int pack_block (WavpackContext *wpc, int32_t *buffer)
{
    WavpackStream *wps = wpc->streams [wpc->current_stream];
    uint32_t flags = wps->wphdr.flags, sflags = wps->wphdr.flags;
    uint32_t sample_count = wps->wphdr.block_samples;
    int32_t *orig_data = NULL;

    if (flags & SHIFT_MASK) {
      int shift = (flags & SHIFT_MASK) >> SHIFT_LSB;
      int mag = (flags & MAG_MASK) >> MAG_LSB;
      uint32_t cnt = sample_count;
      int32_t *ptr = buffer;

      if (flags & MONO_DATA)
          while (cnt--)
            *ptr++ >>= shift;
      else
          while (cnt--) {
            *ptr++ >>= shift;
            *ptr++ >>= shift;
          }

      if ((mag -= shift) < 0)
          flags &= ~MAG_MASK;
      else
          flags -= (1 << MAG_LSB) * shift;

      wps->wphdr.flags = flags;
    }

    if ((flags & FLOAT_DATA) || (flags & MAG_MASK) >> MAG_LSB >= 24) {
      if ((!(flags & HYBRID_FLAG) || wpc->wvc_flag) && !(wpc->config.flags & CONFIG_SKIP_WVX)) {
          orig_data = malloc (sizeof (f32) * ((flags & MONO_DATA) ? sample_count : sample_count * 2));
          memcpy (orig_data, buffer, sizeof (f32) * ((flags & MONO_DATA) ? sample_count : sample_count * 2));

          if (flags & FLOAT_DATA) {
            wps->float_norm_exp = wpc->config.float_norm_exp;

            if (!scan_float_data (wps, (f32 *) buffer, (flags & MONO_DATA) ? sample_count : sample_count * 2)) {
                free (orig_data);
                orig_data = NULL;
            }
          }
          else {
            if (!scan_int32_data (wps, buffer, (flags & MONO_DATA) ? sample_count : sample_count * 2)) {
                free (orig_data);
                orig_data = NULL;
            }
          }
      }
      else {
          if (flags & FLOAT_DATA) {
            wps->float_norm_exp = wpc->config.float_norm_exp;

            if (scan_float_data (wps, (f32 *) buffer, (flags & MONO_DATA) ? sample_count : sample_count * 2))
                wpc->lossy_blocks = TRUE;
          }
          else if (scan_int32_data (wps, buffer, (flags & MONO_DATA) ? sample_count : sample_count * 2))
            wpc->lossy_blocks = TRUE;
      }

      wpc->config.extra_flags |= EXTRA_SCAN_ONLY;
    }
    else if (wpc->config.extra_flags)
      scan_int32_data (wps, buffer, (flags & MONO_DATA) ? sample_count : sample_count * 2);
    else {
      scan_int32_quick (wps, buffer, (flags & MONO_DATA) ? sample_count : sample_count * 2);

      if (wps->shift != wps->int32_zeros + wps->int32_ones + wps->int32_dups) {
          wps->shift = wps->int32_zeros + wps->int32_ones + wps->int32_dups;
          wps->num_terms = 0;
      }
    }

    if (wpc->config.extra_flags) {
      if (flags & MONO_DATA)
          analyze_mono (wpc, buffer);
      else
          analyze_stereo (wpc, buffer);
    }
    else if (!wps->sample_index || !wps->num_terms) {
      wpc->config.extra_flags = EXTRA_SCAN_ONLY;

      if (flags & MONO_DATA)
          analyze_mono (wpc, buffer);
      else
          analyze_stereo (wpc, buffer);

      wpc->config.extra_flags = 0;
    }

    if (!pack_samples (wpc, buffer)) {
      wps->wphdr.flags = sflags;

      if (orig_data)
          free (orig_data);

      return FALSE;
    }
    else
      wps->wphdr.flags = sflags;

    if (orig_data) {
      uint32_t data_count;
      uchar *cptr;

      if (wpc->wvc_flag)
          cptr = wps->block2buff + ((WavpackHeader *) wps->block2buff)->ckSize + 8;
      else
          cptr = wps->blockbuff + ((WavpackHeader *) wps->blockbuff)->ckSize + 8;

      bs_open_write (&wps->wvxbits, cptr + 8, wpc->wvc_flag ? wps->block2end : wps->blockend);

      if (flags & FLOAT_DATA)
          send_float_data (wps, (f32*) orig_data, (flags & MONO_DATA) ? sample_count : sample_count * 2);
      else
          send_int32_data (wps, orig_data, (flags & MONO_DATA) ? sample_count : sample_count * 2);

      data_count = bs_close_write (&wps->wvxbits);
      free (orig_data);

      if (data_count) {
          if (data_count != (uint32_t) -1) {
            *cptr++ = ID_WVX_BITSTREAM | ID_LARGE;
            *cptr++ = (data_count += 4) >> 1;
            *cptr++ = data_count >> 9;
            *cptr++ = data_count >> 17;
            *cptr++ = wps->crc_x;
            *cptr++ = wps->crc_x >> 8;
            *cptr++ = wps->crc_x >> 16;
            *cptr = wps->crc_x >> 24;

            if (wpc->wvc_flag)
                ((WavpackHeader *) wps->block2buff)->ckSize += data_count + 4;
            else
                ((WavpackHeader *) wps->blockbuff)->ckSize += data_count + 4;
          }
          else
            return FALSE;
      }
    }

    return TRUE;
}

// Quickly scan a buffer of long integer data and determine whether any
// redundancy in the LSBs can be used to reduce the data's magnitude. If yes,
// then the INT32_DATA flag is set and the int32 parameters are set. This
// version is designed to terminate as soon as it figures out that no
// redundancy is available so that it can be used for all files.

static void scan_int32_quick (WavpackStream *wps, int32_t *values, int32_t num_values)
{
    uint32_t magdata = 0, ordata = 0, xordata = 0, anddata = ~0;
    int total_shift = 0;
    int32_t *dp, count;

    wps->int32_sent_bits = wps->int32_zeros = wps->int32_ones = wps->int32_dups = 0;

    for (dp = values, count = num_values; count--; dp++) {
      magdata |= (*dp < 0) ? ~*dp : *dp;
      xordata |= *dp ^ -(*dp & 1);
      anddata &= *dp;
      ordata |= *dp;

      if ((ordata & 1) && !(anddata & 1) && (xordata & 2))
          return;
    }

    wps->wphdr.flags &= ~MAG_MASK;

    while (magdata) {
      wps->wphdr.flags += 1 << MAG_LSB;
      magdata >>= 1;
    }

    if (!(wps->wphdr.flags & MAG_MASK))
      return;

    if (!(ordata & 1))
      while (!(ordata & 1)) {
          wps->wphdr.flags -= 1 << MAG_LSB;
          wps->int32_zeros++;
          total_shift++;
          ordata >>= 1;
      }
    else if (anddata & 1)
      while (anddata & 1) {
          wps->wphdr.flags -= 1 << MAG_LSB;
          wps->int32_ones++;
          total_shift++;
          anddata >>= 1;
      }
    else if (!(xordata & 2))
      while (!(xordata & 2)) {
          wps->wphdr.flags -= 1 << MAG_LSB;
          wps->int32_dups++;
          total_shift++;
          xordata >>= 1;
      }

    if (total_shift) {
      wps->wphdr.flags |= INT32_DATA;

      for (dp = values, count = num_values; count--; dp++)
          *dp >>= total_shift;
    }
}

// Scan a buffer of long integer data and determine whether any redundancy in
// the LSBs can be used to reduce the data's magnitude. If yes, then the
// INT32_DATA flag is set and the int32 parameters are set. If bits must still
// be transmitted literally to get down to 24 bits (which is all the integer
// compression code can handle) then we return TRUE to indicate that a wvx
// stream must be created in either lossless mode.

static int scan_int32_data (WavpackStream *wps, int32_t *values, int32_t num_values)
{
    uint32_t magdata = 0, ordata = 0, xordata = 0, anddata = ~0;
    uint32_t crc = 0xffffffff;
    int total_shift = 0;
    int32_t *dp, count;

    wps->int32_sent_bits = wps->int32_zeros = wps->int32_ones = wps->int32_dups = 0;

    for (dp = values, count = num_values; count--; dp++) {
      crc = crc * 9 + (*dp & 0xffff) * 3 + ((*dp >> 16) & 0xffff);
      magdata |= (*dp < 0) ? ~*dp : *dp;
      xordata |= *dp ^ -(*dp & 1);
      anddata &= *dp;
      ordata |= *dp;
    }

    wps->crc_x = crc;
    wps->wphdr.flags &= ~MAG_MASK;

    while (magdata) {
      wps->wphdr.flags += 1 << MAG_LSB;
      magdata >>= 1;
    }

    if (!((wps->wphdr.flags & MAG_MASK) >> MAG_LSB)) {
      wps->wphdr.flags &= ~INT32_DATA;
      return FALSE;
    }

    if (!(ordata & 1))
      while (!(ordata & 1)) {
          wps->wphdr.flags -= 1 << MAG_LSB;
          wps->int32_zeros++;
          total_shift++;
          ordata >>= 1;
      }
    else if (anddata & 1)
      while (anddata & 1) {
          wps->wphdr.flags -= 1 << MAG_LSB;
          wps->int32_ones++;
          total_shift++;
          anddata >>= 1;
      }
    else if (!(xordata & 2))
      while (!(xordata & 2)) {
          wps->wphdr.flags -= 1 << MAG_LSB;
          wps->int32_dups++;
          total_shift++;
          xordata >>= 1;
      }

    if (((wps->wphdr.flags & MAG_MASK) >> MAG_LSB) > 23) {
      wps->int32_sent_bits = ((wps->wphdr.flags & MAG_MASK) >> MAG_LSB) - 23;
      total_shift += wps->int32_sent_bits;
      wps->wphdr.flags &= ~MAG_MASK;
      wps->wphdr.flags += 23 << MAG_LSB;
    }

    if (total_shift) {
      wps->wphdr.flags |= INT32_DATA;

      for (dp = values, count = num_values; count--; dp++)
          *dp >>= total_shift;
    }

    return wps->int32_sent_bits;
}

// For the specified buffer values and the int32 parameters stored in "wps",
// send the literal bits required to the "wvxbits" bitstream.

static void send_int32_data (WavpackStream *wps, int32_t *values, int32_t num_values)
{
    int sent_bits = wps->int32_sent_bits, pre_shift;
    int32_t mask = (1 << sent_bits) - 1;
    int32_t count, value, *dp;

    pre_shift = wps->int32_zeros + wps->int32_ones + wps->int32_dups;

    if (sent_bits)
      for (dp = values, count = num_values; count--; dp++) {
          value = (*dp >> pre_shift) & mask;
          putbits (value, sent_bits, &wps->wvxbits);
      }
}

// Pack an entire block of samples (either mono or stereo) into a completed
// WavPack block. It is assumed that there is sufficient space for the
// completed block at "wps->blockbuff" and that "wps->blockend" points to the
// end of the available space. A return value of FALSE indicates an error.
// Any unsent metadata is transmitted first, then required metadata for this
// block is sent, and finally the compressed integer data is sent. If a "wpx"
// stream is required for floating point data or large integer data, then this
// must be handled outside this function. To find out how much data was written
// the caller must look at the ckSize field of the written WavpackHeader, NOT
// the one in the WavpackStream.

static void decorr_stereo_pass (struct decorr_pass *dpp, int32_t *buffer, int32_t sample_count);
static void decorr_stereo_pass_i (struct decorr_pass *dpp, int32_t *buffer, int32_t sample_count);
static void decorr_stereo_pass_id2 (struct decorr_pass *dpp, int32_t *buffer, int32_t sample_count);

static int pack_samples (WavpackContext *wpc, int32_t *buffer)
{
    WavpackStream *wps = wpc->streams [wpc->current_stream];
    uint32_t sample_count = wps->wphdr.block_samples;
    uint32_t flags = wps->wphdr.flags, data_count;
    int mag16 = ((flags & MAG_MASK) >> MAG_LSB) >= 16;
    int tcount, lossy = FALSE, m = 0;
    double noise_acc = 0.0, noise;
    struct decorr_pass *dpp;
    WavpackMetadata wpmd;
    uint32_t crc, crc2, i;
    int32_t *bptr;

    crc = crc2 = 0xffffffff;

    wps->wphdr.ckSize = sizeof (WavpackHeader) - 8;
    memcpy (wps->blockbuff, &wps->wphdr, sizeof (WavpackHeader));

    if (wpc->metacount) {
      WavpackMetadata *wpmdp = wpc->metadata;

      while (wpc->metacount) {
          copy_metadata (wpmdp, wps->blockbuff, wps->blockend);
          wpc->metabytes -= wpmdp->byte_length;
          free_metadata (wpmdp++);
          wpc->metacount--;
      }

      free (wpc->metadata);
      wpc->metadata = NULL;
    }

    if (!sample_count)
      return TRUE;

    write_decorr_terms (wps, &wpmd);
    copy_metadata (&wpmd, wps->blockbuff, wps->blockend);
    free_metadata (&wpmd);

    write_decorr_weights (wps, &wpmd);
    copy_metadata (&wpmd, wps->blockbuff, wps->blockend);
    free_metadata (&wpmd);

    write_decorr_samples (wps, &wpmd);
    copy_metadata (&wpmd, wps->blockbuff, wps->blockend);
    free_metadata (&wpmd);

    write_entropy_vars (wps, &wpmd);
    copy_metadata (&wpmd, wps->blockbuff, wps->blockend);
    free_metadata (&wpmd);

    if ((flags & SRATE_MASK) == SRATE_MASK && wpc->config.sample_rate != 44100) {
      write_sample_rate (wpc, &wpmd);
      copy_metadata (&wpmd, wps->blockbuff, wps->blockend);
      free_metadata (&wpmd);
    }

    if (flags & HYBRID_FLAG) {
      write_hybrid_profile (wps, &wpmd);
      copy_metadata (&wpmd, wps->blockbuff, wps->blockend);
      free_metadata (&wpmd);
    }

    if (flags & FLOAT_DATA) {
      write_float_info (wps, &wpmd);
      copy_metadata (&wpmd, wps->blockbuff, wps->blockend);
      free_metadata (&wpmd);
    }

    if (flags & INT32_DATA) {
      write_int32_info (wps, &wpmd);
      copy_metadata (&wpmd, wps->blockbuff, wps->blockend);
      free_metadata (&wpmd);
    }

    if ((flags & INITIAL_BLOCK) &&
      (wpc->config.num_channels > 2 ||
      wpc->config.channel_mask != 0x5 - wpc->config.num_channels)) {
          write_channel_info (wpc, &wpmd);
          copy_metadata (&wpmd, wps->blockbuff, wps->blockend);
          free_metadata (&wpmd);
    }

    if ((flags & INITIAL_BLOCK) && !wps->sample_index) {
      write_config_info (wpc, &wpmd);
      copy_metadata (&wpmd, wps->blockbuff, wps->blockend);
      free_metadata (&wpmd);
    }

    bs_open_write (&wps->wvbits, wps->blockbuff + ((WavpackHeader *) wps->blockbuff)->ckSize + 12, wps->blockend);

    if (wpc->wvc_flag) {
      wps->wphdr.ckSize = sizeof (WavpackHeader) - 8;
      memcpy (wps->block2buff, &wps->wphdr, sizeof (WavpackHeader));

      if (flags & HYBRID_SHAPE) {
          write_shaping_info (wps, &wpmd);
          copy_metadata (&wpmd, wps->block2buff, wps->block2end);
          free_metadata (&wpmd);
      }

      bs_open_write (&wps->wvcbits, wps->block2buff + ((WavpackHeader *) wps->block2buff)->ckSize + 12, wps->block2end);
    }

    /////////////////////// handle lossless mono mode /////////////////////////

    if (!(flags & HYBRID_FLAG) && (flags & MONO_DATA))
      for (bptr = buffer, i = 0; i < sample_count; ++i) {
          int32_t code;

          crc = crc * 3 + (code = *bptr++);

          for (tcount = wps->num_terms, dpp = wps->decorr_passes; tcount--; dpp++) {
            int32_t sam;

            if (dpp->term > MAX_TERM) {
                if (dpp->term & 1)
                  sam = 2 * dpp->samples_A [0] - dpp->samples_A [1];
                else
                  sam = (3 * dpp->samples_A [0] - dpp->samples_A [1]) >> 1;

                dpp->samples_A [1] = dpp->samples_A [0];
                dpp->samples_A [0] = code;
            }
            else {
                sam = dpp->samples_A [m];
                dpp->samples_A [(m + dpp->term) & (MAX_TERM - 1)] = code;
            }

            code -= apply_weight (dpp->weight_A, sam);
            update_weight (dpp->weight_A, dpp->delta, sam, code);
          }

          m = (m + 1) & (MAX_TERM - 1);
          send_word_lossless (wps, code, 0);
      }

    //////////////////// handle the lossless stereo mode //////////////////////

#ifdef FAST_ENCODE
    else if (!(flags & HYBRID_FLAG) && !(flags & MONO_DATA)) {
      int32_t *eptr = buffer + (sample_count * 2);

      if (flags & JOINT_STEREO)
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            crc = crc * 9 + bptr [0] * 3 + bptr [1];
            bptr [1] += ((bptr [0] -= bptr [1]) >> 1);
          }
      else
          for (bptr = buffer; bptr < eptr; bptr += 2)
            crc = crc * 9 + bptr [0] * 3 + bptr [1];

      for (tcount = wps->num_terms, dpp = wps->decorr_passes; tcount-- ; dpp++)
          if (((flags & MAG_MASK) >> MAG_LSB) >= 16)
            decorr_stereo_pass (dpp, buffer, sample_count);
          else if (dpp->delta != 2)
            decorr_stereo_pass_i (dpp, buffer, sample_count);
          else
            decorr_stereo_pass_id2 (dpp, buffer, sample_count);

      for (bptr = buffer; bptr < eptr; bptr += 2) {
          send_word_lossless (wps, bptr [0], 0);
          send_word_lossless (wps, bptr [1], 1);
      }

      m = sample_count & (MAX_TERM - 1);
    }
#else
    else if (!(flags & HYBRID_FLAG) && !(flags & MONO_DATA))
      for (bptr = buffer, i = 0; i < sample_count; ++i, bptr += 2) {
          int32_t left, right, sam_A, sam_B;

          crc = crc * 3 + (left = bptr [0]);
          crc = crc * 3 + (right = bptr [1]);

          if (flags & JOINT_STEREO)
            right += ((left -= right) >> 1);

          for (tcount = wps->num_terms, dpp = wps->decorr_passes; tcount-- ; dpp++) {
            if (dpp->term > 0) {
                if (dpp->term > MAX_TERM) {
                  if (dpp->term & 1) {
                      sam_A = 2 * dpp->samples_A [0] - dpp->samples_A [1];
                      sam_B = 2 * dpp->samples_B [0] - dpp->samples_B [1];
                  }
                  else {
                      sam_A = (3 * dpp->samples_A [0] - dpp->samples_A [1]) >> 1;
                      sam_B = (3 * dpp->samples_B [0] - dpp->samples_B [1]) >> 1;
                  }

                  dpp->samples_A [1] = dpp->samples_A [0];
                  dpp->samples_B [1] = dpp->samples_B [0];
                  dpp->samples_A [0] = left;
                  dpp->samples_B [0] = right;
                }
                else {
                  int k = (m + dpp->term) & (MAX_TERM - 1);

                  sam_A = dpp->samples_A [m];
                  sam_B = dpp->samples_B [m];
                  dpp->samples_A [k] = left;
                  dpp->samples_B [k] = right;
                }

                left -= apply_weight (dpp->weight_A, sam_A);
                right -= apply_weight (dpp->weight_B, sam_B);
                update_weight (dpp->weight_A, dpp->delta, sam_A, left);
                update_weight (dpp->weight_B, dpp->delta, sam_B, right);
            }
            else {
                sam_A = (dpp->term == -2) ? right : dpp->samples_A [0];
                sam_B = (dpp->term == -1) ? left : dpp->samples_B [0];
                dpp->samples_A [0] = right;
                dpp->samples_B [0] = left;
                left -= apply_weight (dpp->weight_A, sam_A);
                right -= apply_weight (dpp->weight_B, sam_B);
                update_weight_clip (dpp->weight_A, dpp->delta, sam_A, left);
                update_weight_clip (dpp->weight_B, dpp->delta, sam_B, right);
            }
          }

          m = (m + 1) & (MAX_TERM - 1);
          send_word_lossless (wps, left, 0);
          send_word_lossless (wps, right, 1);
      }
#endif

    /////////////////// handle the lossy/hybrid mono mode /////////////////////

    else if ((flags & HYBRID_FLAG) && (flags & MONO_DATA))
      for (bptr = buffer, i = 0; i < sample_count; ++i) {
          int32_t code, temp;

          crc2 = crc2 * 3 + (code = *bptr++);

          if (flags & HYBRID_SHAPE) {
            int shaping_weight = (wps->dc.shaping_acc [0] += wps->dc.shaping_delta [0]) >> 16;
            temp = -apply_weight (shaping_weight, wps->dc.error [0]);

            if ((flags & NEW_SHAPING) && shaping_weight < 0 && temp) {
                if (temp == wps->dc.error [0])
                  temp = (temp < 0) ? temp + 1 : temp - 1;

                wps->dc.error [0] = -code;
                code += temp;
            }
            else
                wps->dc.error [0] = -(code += temp);
          }

          for (tcount = wps->num_terms, dpp = wps->decorr_passes; tcount-- ; dpp++)
            if (dpp->term > MAX_TERM) {
                if (dpp->term & 1)
                  dpp->samples_A [2] = 2 * dpp->samples_A [0] - dpp->samples_A [1];
                else
                  dpp->samples_A [2] = (3 * dpp->samples_A [0] - dpp->samples_A [1]) >> 1;

                code -= (dpp->aweight_A = apply_weight (dpp->weight_A, dpp->samples_A [2]));
            }
            else
                code -= (dpp->aweight_A = apply_weight (dpp->weight_A, dpp->samples_A [m]));

          code = send_word (wps, code, 0);

          while (--dpp >= wps->decorr_passes) {
            if (dpp->term > MAX_TERM) {
                update_weight (dpp->weight_A, dpp->delta, dpp->samples_A [2], code);
                dpp->samples_A [1] = dpp->samples_A [0];
                dpp->samples_A [0] = (code += dpp->aweight_A);
            }
            else {
                int32_t sam = dpp->samples_A [m];

                update_weight (dpp->weight_A, dpp->delta, sam, code);
                dpp->samples_A [(m + dpp->term) & (MAX_TERM - 1)] = (code += dpp->aweight_A);
            }
          }

          wps->dc.error [0] += code;
          m = (m + 1) & (MAX_TERM - 1);

          if ((crc = crc * 3 + code) != crc2)
            lossy = TRUE;

          if (wpc->config.flags & CONFIG_CALC_NOISE) {
            noise = code - bptr [-1];

            noise_acc += noise *= noise;
            wps->dc.noise_ave = (wps->dc.noise_ave * 0.99) + (noise * 0.01);

            if (wps->dc.noise_ave > wps->dc.noise_max)
                wps->dc.noise_max = wps->dc.noise_ave;
          }
      }

    /////////////////// handle the lossy/hybrid stereo mode ///////////////////

    else if ((flags & HYBRID_FLAG) && !(flags & MONO_DATA))
      for (bptr = buffer, i = 0; i < sample_count; ++i) {
          int32_t left, right, temp;
          int shaping_weight;

          left = *bptr++;
          crc2 = (crc2 * 3 + left) * 3 + (right = *bptr++);

          if (flags & HYBRID_SHAPE) {
            shaping_weight = (wps->dc.shaping_acc [0] += wps->dc.shaping_delta [0]) >> 16;
            temp = -apply_weight (shaping_weight, wps->dc.error [0]);

            if ((flags & NEW_SHAPING) && shaping_weight < 0 && temp) {
                if (temp == wps->dc.error [0])
                  temp = (temp < 0) ? temp + 1 : temp - 1;

                wps->dc.error [0] = -left;
                left += temp;
            }
            else
                wps->dc.error [0] = -(left += temp);

            shaping_weight = (wps->dc.shaping_acc [1] += wps->dc.shaping_delta [1]) >> 16;
            temp = -apply_weight (shaping_weight, wps->dc.error [1]);

            if ((flags & NEW_SHAPING) && shaping_weight < 0 && temp) {
                if (temp == wps->dc.error [1])
                  temp = (temp < 0) ? temp + 1 : temp - 1;

                wps->dc.error [1] = -right;
                right += temp;
            }
            else
                wps->dc.error [1] = -(right += temp);
          }

          if (flags & JOINT_STEREO)
            right += ((left -= right) >> 1);

          for (tcount = wps->num_terms, dpp = wps->decorr_passes; tcount-- ; dpp++)
            if (dpp->term > MAX_TERM) {
                if (dpp->term & 1) {
                  dpp->samples_A [2] = 2 * dpp->samples_A [0] - dpp->samples_A [1];
                  dpp->samples_B [2] = 2 * dpp->samples_B [0] - dpp->samples_B [1];
                }
                else {
                  dpp->samples_A [2] = (3 * dpp->samples_A [0] - dpp->samples_A [1]) >> 1;
                  dpp->samples_B [2] = (3 * dpp->samples_B [0] - dpp->samples_B [1]) >> 1;
                }

                left -= (dpp->aweight_A = apply_weight (dpp->weight_A, dpp->samples_A [2]));
                right -= (dpp->aweight_B = apply_weight (dpp->weight_B, dpp->samples_B [2]));
            }
            else if (dpp->term > 0) {
                left -= (dpp->aweight_A = apply_weight (dpp->weight_A, dpp->samples_A [m]));
                right -= (dpp->aweight_B = apply_weight (dpp->weight_B, dpp->samples_B [m]));
            }
            else {
                if (dpp->term == -1)
                  dpp->samples_B [0] = left;
                else if (dpp->term == -2)
                  dpp->samples_A [0] = right;

                left -= (dpp->aweight_A = apply_weight (dpp->weight_A, dpp->samples_A [0]));
                right -= (dpp->aweight_B = apply_weight (dpp->weight_B, dpp->samples_B [0]));
            }

          left = send_word (wps, left, 0);
          right = send_word (wps, right, 1);

          while (--dpp >= wps->decorr_passes)
            if (dpp->term > MAX_TERM) {
                update_weight (dpp->weight_A, dpp->delta, dpp->samples_A [2], left);
                update_weight (dpp->weight_B, dpp->delta, dpp->samples_B [2], right);

                dpp->samples_A [1] = dpp->samples_A [0];
                dpp->samples_B [1] = dpp->samples_B [0];

                dpp->samples_A [0] = (left += dpp->aweight_A);
                dpp->samples_B [0] = (right += dpp->aweight_B);
            }
            else if (dpp->term > 0) {
                int k = (m + dpp->term) & (MAX_TERM - 1);

                update_weight (dpp->weight_A, dpp->delta, dpp->samples_A [m], left);
                dpp->samples_A [k] = (left += dpp->aweight_A);

                update_weight (dpp->weight_B, dpp->delta, dpp->samples_B [m], right);
                dpp->samples_B [k] = (right += dpp->aweight_B);
            }
            else {
                if (dpp->term == -1) {
                  dpp->samples_B [0] = left + dpp->aweight_A;
                  dpp->aweight_B = apply_weight (dpp->weight_B, dpp->samples_B [0]);
                }
                else if (dpp->term == -2) {
                  dpp->samples_A [0] = right + dpp->aweight_B;
                  dpp->aweight_A = apply_weight (dpp->weight_A, dpp->samples_A [0]);
                }

                update_weight_clip (dpp->weight_A, dpp->delta, dpp->samples_A [0], left);
                update_weight_clip (dpp->weight_B, dpp->delta, dpp->samples_B [0], right);
                dpp->samples_B [0] = (left += dpp->aweight_A);
                dpp->samples_A [0] = (right += dpp->aweight_B);
            }

          if (flags & JOINT_STEREO)
            left += (right -= (left >> 1));

          wps->dc.error [0] += left;
          wps->dc.error [1] += right;
          m = (m + 1) & (MAX_TERM - 1);

          if ((crc = (crc * 3 + left) * 3 + right) != crc2)
            lossy = TRUE;

          if (wpc->config.flags & CONFIG_CALC_NOISE) {
            noise = (double)(left - bptr [-2]) * (left - bptr [-2]);
            noise += (double)(right - bptr [-1]) * (right - bptr [-1]);

            noise_acc += noise /= 2.0;
            wps->dc.noise_ave = (wps->dc.noise_ave * 0.99) + (noise * 0.01);

            if (wps->dc.noise_ave > wps->dc.noise_max)
                wps->dc.noise_max = wps->dc.noise_ave;
          }
      }

    if (m)
      for (tcount = wps->num_terms, dpp = wps->decorr_passes; tcount--; dpp++)
          if (dpp->term > 0 && dpp->term <= MAX_TERM) {
            int32_t temp_A [MAX_TERM], temp_B [MAX_TERM];
            int k;

            memcpy (temp_A, dpp->samples_A, sizeof (dpp->samples_A));
            memcpy (temp_B, dpp->samples_B, sizeof (dpp->samples_B));

            for (k = 0; k < MAX_TERM; k++) {
                dpp->samples_A [k] = temp_A [m];
                dpp->samples_B [k] = temp_B [m];
                m = (m + 1) & (MAX_TERM - 1);
            }
          }

    if (wpc->config.flags & CONFIG_CALC_NOISE)
      wps->dc.noise_sum += noise_acc;

    flush_word (wps);
    data_count = bs_close_write (&wps->wvbits);

    if (data_count) {
      if (data_count != (uint32_t) -1) {
          uchar *cptr = wps->blockbuff + ((WavpackHeader *) wps->blockbuff)->ckSize + 8;

          *cptr++ = ID_WV_BITSTREAM | ID_LARGE;
          *cptr++ = data_count >> 1;
          *cptr++ = data_count >> 9;
          *cptr++ = data_count >> 17;
          ((WavpackHeader *) wps->blockbuff)->ckSize += data_count + 4;
      }
      else
          return FALSE;
    }

    ((WavpackHeader *) wps->blockbuff)->crc = crc;

    if (wpc->wvc_flag) {
      data_count = bs_close_write (&wps->wvcbits);

      if (data_count && lossy) {
          if (data_count != (uint32_t) -1) {
            uchar *cptr = wps->block2buff + ((WavpackHeader *) wps->block2buff)->ckSize + 8;

            *cptr++ = ID_WVC_BITSTREAM | ID_LARGE;
            *cptr++ = data_count >> 1;
            *cptr++ = data_count >> 9;
            *cptr++ = data_count >> 17;
            ((WavpackHeader *) wps->block2buff)->ckSize += data_count + 4;
          }
          else
            return FALSE;
      }

      ((WavpackHeader *) wps->block2buff)->crc = crc2;
    }
    else if (lossy)
      wpc->lossy_blocks = TRUE;

    wps->sample_index += sample_count;
    return TRUE;
}

#ifdef FAST_ENCODE

static void decorr_stereo_pass_id2 (struct decorr_pass *dpp, int32_t *buffer, int32_t sample_count)
{
    int32_t *bptr, *eptr = buffer + (sample_count * 2), sam_A, sam_B;
    int m, k;

    switch (dpp->term) {
      case 17:
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = 2 * dpp->samples_A [0] - dpp->samples_A [1];
            dpp->samples_A [1] = dpp->samples_A [0];
            dpp->samples_A [0] = bptr [0];
            bptr [0] -= apply_weight_i (dpp->weight_A, sam_A);
            update_weight_d2 (dpp->weight_A, dpp->delta, sam_A, bptr [0]);

            sam_B = 2 * dpp->samples_B [0] - dpp->samples_B [1];
            dpp->samples_B [1] = dpp->samples_B [0];
            dpp->samples_B [0] = bptr [1];
            bptr [1] -= apply_weight_i (dpp->weight_B, sam_B);
            update_weight_d2 (dpp->weight_B, dpp->delta, sam_B, bptr [1]);
          }

          break;

      case 18:
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = (3 * dpp->samples_A [0] - dpp->samples_A [1]) >> 1;
            dpp->samples_A [1] = dpp->samples_A [0];
            dpp->samples_A [0] = bptr [0];
            bptr [0] -= apply_weight_i (dpp->weight_A, sam_A);
            update_weight_d2 (dpp->weight_A, dpp->delta, sam_A, bptr [0]);

            sam_B = (3 * dpp->samples_B [0] - dpp->samples_B [1]) >> 1;
            dpp->samples_B [1] = dpp->samples_B [0];
            dpp->samples_B [0] = bptr [1];
            bptr [1] -= apply_weight_i (dpp->weight_B, sam_B);
            update_weight_d2 (dpp->weight_B, dpp->delta, sam_B, bptr [1]);
          }

          break;

      case 8:
          for (m = 0, bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = dpp->samples_A [m];
            dpp->samples_A [m] = bptr [0];
            bptr [0] -= apply_weight_i (dpp->weight_A, sam_A);
            update_weight_d2 (dpp->weight_A, dpp->delta, sam_A, bptr [0]);

            sam_B = dpp->samples_B [m];
            dpp->samples_B [m] = bptr [1];
            bptr [1] -= apply_weight_i (dpp->weight_B, sam_B);
            update_weight_d2 (dpp->weight_B, dpp->delta, sam_B, bptr [1]);

            m = (m + 1) & (MAX_TERM - 1);
          }

          break;

      default:
          for (m = 0, k = dpp->term & (MAX_TERM - 1), bptr = buffer; bptr < eptr; bptr += 2) {
            dpp->samples_A [k] = bptr [0];
            bptr [0] -= apply_weight_i (dpp->weight_A, dpp->samples_A [m]);
            update_weight_d2 (dpp->weight_A, dpp->delta, dpp->samples_A [m], bptr [0]);

            dpp->samples_B [k] = bptr [1];
            bptr [1] -= apply_weight_i (dpp->weight_B, dpp->samples_B [m]);
            update_weight_d2 (dpp->weight_B, dpp->delta, dpp->samples_B [m], bptr [1]);

            m = (m + 1) & (MAX_TERM - 1);
            k = (k + 1) & (MAX_TERM - 1);
          }

          break;

      case -1:
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = dpp->samples_A [0];
            sam_B = bptr [0];
            dpp->samples_A [0] = bptr [1];
            bptr [0] -= apply_weight_i (dpp->weight_A, sam_A);
            update_weight_clip_d2 (dpp->weight_A, dpp->delta, sam_A, bptr [0]);
            bptr [1] -= apply_weight_i (dpp->weight_B, sam_B);
            update_weight_clip_d2 (dpp->weight_B, dpp->delta, sam_B, bptr [1]);
          }

          break;

      case -2:
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = bptr [1];
            sam_B = dpp->samples_B [0];
            dpp->samples_B [0] = bptr [0];
            bptr [0] -= apply_weight_i (dpp->weight_A, sam_A);
            update_weight_clip_d2 (dpp->weight_A, dpp->delta, sam_A, bptr [0]);
            bptr [1] -= apply_weight_i (dpp->weight_B, sam_B);
            update_weight_clip_d2 (dpp->weight_B, dpp->delta, sam_B, bptr [1]);
          }

          break;

      case -3:
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = dpp->samples_A [0];
            sam_B = dpp->samples_B [0];
            dpp->samples_A [0] = bptr [1];
            dpp->samples_B [0] = bptr [0];
            bptr [0] -= apply_weight_i (dpp->weight_A, sam_A);
            update_weight_clip_d2 (dpp->weight_A, dpp->delta, sam_A, bptr [0]);
            bptr [1] -= apply_weight_i (dpp->weight_B, sam_B);
            update_weight_clip_d2 (dpp->weight_B, dpp->delta, sam_B, bptr [1]);
          }

          break;
    }
}

static void decorr_stereo_pass_i (struct decorr_pass *dpp, int32_t *buffer, int32_t sample_count)
{
    int32_t *bptr, *eptr = buffer + (sample_count * 2), sam_A, sam_B;
    int m, k;

    switch (dpp->term) {
      case 17:
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = 2 * dpp->samples_A [0] - dpp->samples_A [1];
            dpp->samples_A [1] = dpp->samples_A [0];
            dpp->samples_A [0] = bptr [0];
            bptr [0] -= apply_weight_i (dpp->weight_A, sam_A);
            update_weight (dpp->weight_A, dpp->delta, sam_A, bptr [0]);

            sam_B = 2 * dpp->samples_B [0] - dpp->samples_B [1];
            dpp->samples_B [1] = dpp->samples_B [0];
            dpp->samples_B [0] = bptr [1];
            bptr [1] -= apply_weight_i (dpp->weight_B, sam_B);
            update_weight (dpp->weight_B, dpp->delta, sam_B, bptr [1]);
          }

          break;

      case 18:
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = (3 * dpp->samples_A [0] - dpp->samples_A [1]) >> 1;
            dpp->samples_A [1] = dpp->samples_A [0];
            dpp->samples_A [0] = bptr [0];
            bptr [0] -= apply_weight_i (dpp->weight_A, sam_A);
            update_weight (dpp->weight_A, dpp->delta, sam_A, bptr [0]);

            sam_B = (3 * dpp->samples_B [0] - dpp->samples_B [1]) >> 1;
            dpp->samples_B [1] = dpp->samples_B [0];
            dpp->samples_B [0] = bptr [1];
            bptr [1] -= apply_weight_i (dpp->weight_B, sam_B);
            update_weight (dpp->weight_B, dpp->delta, sam_B, bptr [1]);
          }

          break;

      default:
          for (m = 0, k = dpp->term & (MAX_TERM - 1), bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = dpp->samples_A [m];
            dpp->samples_A [k] = bptr [0];
            bptr [0] -= apply_weight_i (dpp->weight_A, sam_A);
            update_weight (dpp->weight_A, dpp->delta, sam_A, bptr [0]);

            sam_B = dpp->samples_B [m];
            dpp->samples_B [k] = bptr [1];
            bptr [1] -= apply_weight_i (dpp->weight_B, sam_B);
            update_weight (dpp->weight_B, dpp->delta, sam_B, bptr [1]);

            m = (m + 1) & (MAX_TERM - 1);
            k = (k + 1) & (MAX_TERM - 1);
          }

          break;

      case -1:
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = dpp->samples_A [0];
            sam_B = bptr [0];
            dpp->samples_A [0] = bptr [1];
            bptr [0] -= apply_weight_i (dpp->weight_A, sam_A);
            update_weight_clip (dpp->weight_A, dpp->delta, sam_A, bptr [0]);
            bptr [1] -= apply_weight_i (dpp->weight_B, sam_B);
            update_weight_clip (dpp->weight_B, dpp->delta, sam_B, bptr [1]);
          }

          break;

      case -2:
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = bptr [1];
            sam_B = dpp->samples_B [0];
            dpp->samples_B [0] = bptr [0];
            bptr [0] -= apply_weight_i (dpp->weight_A, sam_A);
            update_weight_clip (dpp->weight_A, dpp->delta, sam_A, bptr [0]);
            bptr [1] -= apply_weight_i (dpp->weight_B, sam_B);
            update_weight_clip (dpp->weight_B, dpp->delta, sam_B, bptr [1]);
          }

          break;

      case -3:
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = dpp->samples_A [0];
            sam_B = dpp->samples_B [0];
            dpp->samples_A [0] = bptr [1];
            dpp->samples_B [0] = bptr [0];
            bptr [0] -= apply_weight_i (dpp->weight_A, sam_A);
            update_weight_clip (dpp->weight_A, dpp->delta, sam_A, bptr [0]);
            bptr [1] -= apply_weight_i (dpp->weight_B, sam_B);
            update_weight_clip (dpp->weight_B, dpp->delta, sam_B, bptr [1]);
          }

          break;
    }
}

static void decorr_stereo_pass (struct decorr_pass *dpp, int32_t *buffer, int32_t sample_count)
{
    int32_t *bptr, *eptr = buffer + (sample_count * 2), sam_A, sam_B;
    int m, k;

    switch (dpp->term) {
      case 17:
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = 2 * dpp->samples_A [0] - dpp->samples_A [1];
            dpp->samples_A [1] = dpp->samples_A [0];
            dpp->samples_A [0] = bptr [0];
            bptr [0] -= apply_weight (dpp->weight_A, sam_A);
            update_weight (dpp->weight_A, dpp->delta, sam_A, bptr [0]);

            sam_B = 2 * dpp->samples_B [0] - dpp->samples_B [1];
            dpp->samples_B [1] = dpp->samples_B [0];
            dpp->samples_B [0] = bptr [1];
            bptr [1] -= apply_weight (dpp->weight_B, sam_B);
            update_weight (dpp->weight_B, dpp->delta, sam_B, bptr [1]);
          }

          break;

      case 18:
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = (3 * dpp->samples_A [0] - dpp->samples_A [1]) >> 1;
            dpp->samples_A [1] = dpp->samples_A [0];
            dpp->samples_A [0] = bptr [0];
            bptr [0] -= apply_weight (dpp->weight_A, sam_A);
            update_weight (dpp->weight_A, dpp->delta, sam_A, bptr [0]);

            sam_B = (3 * dpp->samples_B [0] - dpp->samples_B [1]) >> 1;
            dpp->samples_B [1] = dpp->samples_B [0];
            dpp->samples_B [0] = bptr [1];
            bptr [1] -= apply_weight (dpp->weight_B, sam_B);
            update_weight (dpp->weight_B, dpp->delta, sam_B, bptr [1]);
          }

          break;

      default:
          for (m = 0, k = dpp->term & (MAX_TERM - 1), bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = dpp->samples_A [m];
            dpp->samples_A [k] = bptr [0];
            bptr [0] -= apply_weight (dpp->weight_A, sam_A);
            update_weight (dpp->weight_A, dpp->delta, sam_A, bptr [0]);

            sam_B = dpp->samples_B [m];
            dpp->samples_B [k] = bptr [1];
            bptr [1] -= apply_weight (dpp->weight_B, sam_B);
            update_weight (dpp->weight_B, dpp->delta, sam_B, bptr [1]);

            m = (m + 1) & (MAX_TERM - 1);
            k = (k + 1) & (MAX_TERM - 1);
          }

          break;

      case -1:
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = dpp->samples_A [0];
            sam_B = bptr [0];
            dpp->samples_A [0] = bptr [1];
            bptr [0] -= apply_weight (dpp->weight_A, sam_A);
            update_weight_clip (dpp->weight_A, dpp->delta, sam_A, bptr [0]);
            bptr [1] -= apply_weight (dpp->weight_B, sam_B);
            update_weight_clip (dpp->weight_B, dpp->delta, sam_B, bptr [1]);
          }

          break;

      case -2:
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = bptr [1];
            sam_B = dpp->samples_B [0];
            dpp->samples_B [0] = bptr [0];
            bptr [0] -= apply_weight (dpp->weight_A, sam_A);
            update_weight_clip (dpp->weight_A, dpp->delta, sam_A, bptr [0]);
            bptr [1] -= apply_weight (dpp->weight_B, sam_B);
            update_weight_clip (dpp->weight_B, dpp->delta, sam_B, bptr [1]);
          }

          break;

      case -3:
          for (bptr = buffer; bptr < eptr; bptr += 2) {
            sam_A = dpp->samples_A [0];
            sam_B = dpp->samples_B [0];
            dpp->samples_A [0] = bptr [1];
            dpp->samples_B [0] = bptr [0];
            bptr [0] -= apply_weight (dpp->weight_A, sam_A);
            update_weight_clip (dpp->weight_A, dpp->delta, sam_A, bptr [0]);
            bptr [1] -= apply_weight (dpp->weight_B, sam_B);
            update_weight_clip (dpp->weight_B, dpp->delta, sam_B, bptr [1]);
          }

          break;
    }
}

#endif

//////////////////////////////////////////////////////////////////////////////
// This function returns the accumulated RMS noise as a double if the       //
// CALC_NOISE bit was set in the WavPack header. The peak noise can also be //
// returned if desired. See wavpack.c for the calculations required to      //
// convert this into decibels of noise below full scale.                    //
//////////////////////////////////////////////////////////////////////////////

double pack_noise (WavpackContext *wpc, double *peak)
{
    WavpackStream *wps = wpc->streams [wpc->current_stream];

    if (peak)
      *peak = wps->dc.noise_max;

    return wps->dc.noise_sum;
}

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