sharedbook.c

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/********************************************************************
 *                                                                  *
 * THIS FILE IS PART OF THE OggVorbis 'TREMOR' CODEC SOURCE CODE.   *
 *                                                                  *
 * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
 * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
 * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
 *                                                                  *
 * THE OggVorbis 'TREMOR' SOURCE CODE IS (C) COPYRIGHT 1994-2002    *
 * BY THE Xiph.Org FOUNDATION http://www.xiph.org/                  *
 *                                                                  *
 ********************************************************************

 function: basic shared codebook operations

 ********************************************************************/

#include <stdlib.h>
#include <string.h>
#include "ogg.h"
#include "os.h"
#include "misc.h"
#include "ivorbiscodec.h"
#include "codebook.h"

/**** pack/unpack helpers ******************************************/
int _ilog(unsigned int v)
{       
  int             ret = 0;

  while (v)
  {
    ret++;
    v               >>= 1;
  }
  return (ret);
}
/* 32 bit float (not IEEE; nonnormalized mantissa +
   biased exponent) : neeeeeee eeemmmmm mmmmmmmm mmmmmmmm 
   Why not IEEE?  It's just not that important here. */

#define VQ_FEXP 10
#define VQ_FMAN 21
#define VQ_FEXP_BIAS 768 /* bias toward values smaller than 1. */

static ogg_int32_t _float32_unpack(long val, int *point)
{       
  long            mant = val & 0x1fffff;
  int             sign = val & 0x80000000;
  long            exp = (val & 0x7fe00000L) >> VQ_FMAN;

  exp -= (VQ_FMAN - 1) + VQ_FEXP_BIAS;
  if (mant)
  {
    while (!(mant & 0x40000000))
    {
      mant            <<= 1;

      exp -= 1;
    }
    if (sign)
      mant = - mant;
  }
  else 
  {
    sign = 0;
    exp = - 9999;
  }
  *point = exp;
  return mant;
}
/* given a list of word lengths, generate a list of codewords.  Works
   for length ordered or unordered, always assigns the lowest valued
   codewords first.  Extended to handle unused entries (length 0) */
ogg_uint32_t *_make_words(long *l, long n, long sparsecount)
{       
  long            i, j, count = 0;
  ogg_uint32_t    marker[33];

  ogg_uint32_t *r = (ogg_uint32_t *) _ogg_malloc((sparsecount ? sparsecount : n) *sizeof(*r));
  memset(marker, 0, sizeof(marker));
  for (i = 0; i < n; i++)
  {
    long            length = l[i];
    if (length > 0)
    {
      ogg_uint32_t    entry = marker[length];

      /* when we claim a node for an entry, we also claim the nodes
  below it (pruning off the imagined tree that may have dangled
  from it) as well as blocking the use of any nodes directly
  above for leaves */
      /* update ourself */
      if (length < 32 && (entry >> length))
      {
        /* error condition; the lengths must specify an overpopulated tree */
        _ogg_free(r);
        return (NULL);
      }
      r[count++] = entry;
      /* Look to see if the next shorter marker points to the node
  above. if so, update it and repeat.  */
      {
        for (j = length; j > 0; j--)
        {
          if (marker[j]& 1)
          {
            /* have to jump branches */
            if (j == 1)
              marker[1]++;
            else
              marker[j] = marker[j - 1] << 1;
            break; /* invariant says next upper marker would already
                                              have been moved if it was on the same path */
          }
          marker[j]++;
        }
      }
      /* prune the tree; the implicit invariant says all the longer
  markers were dangling from our just-taken node.  Dangle them
  from our *new* node. */
      for (j = length + 1; j < 33; j++)
      if ((marker[j] >> 1) == entry)
      {
        entry = marker[j];
        marker[j] = marker[j - 1] << 1;
      }
      else
        break;
    }
    else if (sparsecount == 0)
      count++;
  }
  /* bitreverse the words because our bitwise packer/unpacker is LSb
     endian */
  for (i = 0, count = 0; i < n; i++)
  {
    ogg_uint32_t    temp = 0;

    for (j = 0; j < l[i]; j++)
    {
      temp            <<= 1;

      temp |= (r[count] >> j)& 1;
    }
    if (sparsecount)
    {
      if (l[i])
        r[count++] = temp;
    }
    else
      r[count++] = temp;
  }
  return (r);
}
/* there might be a straightforward one-line way to do the below
   that's portable and totally safe against roundoff, but I haven't
   thought of it.  Therefore, we opt on the side of caution */
long _book_maptype1_quantvals(const static_codebook *b)
{       
         /* get us a starting hint, we'll polish it below */
  int             bits = _ilog(b->entries);
  int             vals = b->entries >> ((bits - 1) *(b->dim - 1) / b->dim);
  while (1)
  {
    long            acc = 1;
    long            acc1 = 1;
    int             i;

    for (i = 0; i < b->dim; i++)
    {
      acc *= vals;
      acc1 *= vals + 1;
    }
    if (acc <= b->entries && acc1 > b->entries)
    {
      return (vals);
    }
    else 
    {
      if (acc > b->entries)
      {
        vals--;
      }
      else 
      {
        vals++;
      }
    }
  }
}
/* different than what _book_unquantize does for mainline:
   we repack the book in a fixed point format that shares the same
   binary point.  Upon first use, we can shift point if needed */

/* we need to deal with two map types: in map type 1, the values are
   generated algorithmically (each column of the vector counts through
   the values in the quant vector). in map type 2, all the values came
   in in an explicit list.  Both value lists must be unpacked */

ogg_int32_t *_book_unquantize(const static_codebook *b, int n, int *sparsemap, int *maxpoint)
{       
  long            j, k, count = 0;
  if (b->maptype == 1 || b->maptype == 2)
  {
    int             quantvals;
    int             minpoint, delpoint;
    ogg_int32_t     mindel = _float32_unpack(b->q_min, &minpoint);
    ogg_int32_t     delta = _float32_unpack(b->q_delta, &delpoint);
    ogg_int32_t     *r = (ogg_int32_t *) _ogg_calloc(n *b->dim, sizeof(*r));
    int             *rp = (int *) _ogg_calloc(n *b->dim, sizeof(*rp));

    *maxpoint = minpoint;
    /* maptype 1 and 2 both use a quantized value vector, but
       different sizes */
    switch (b->maptype)
    {
      case 1:
      /* most of the time, entries%dimensions == 0, but we need to be
  well defined.  We define that the possible vales at each
  scalar is values == entries/dim.  If entries%dim != 0, we'll
  have 'too few' values (values*dim<entries), which means that
  we'll have 'left over' entries; left over entries use zeroed
  values (and are wasted).  So don't generate codebooks like
  that */
      quantvals = _book_maptype1_quantvals(b);
      for (j = 0; j < b->entries; j++)
      {
        if ((sparsemap && b->lengthlist[j]) || !sparsemap)
        {
          ogg_int32_t     last = 0;
          int             lastpoint = 0;
          int             indexdiv = 1;

          for (k = 0; k < b->dim; k++)
          {
            int             index = (j / indexdiv) % quantvals;
            int             point;
            int             val = VFLOAT_MULTI(delta, delpoint, abs(b->quantlist[index]), &point);

            val = VFLOAT_ADD(mindel, minpoint, val, point, &point);
            val = VFLOAT_ADD(last, lastpoint, val, point, &point);
            if (b->q_sequencep)
            {
              last = val;
              lastpoint = point;
            }
            if (sparsemap)
            {
              r[sparsemap[count] *b->dim + k] = val;
              rp[sparsemap[count] *b->dim + k] = point;
            }
            else 
            {
              r[count *b->dim + k] = val;
              rp[count *b->dim + k] = point;
            }
            if (*maxpoint < point)
              *maxpoint = point;
            indexdiv *= quantvals;
          }
          count++;
        }
      }
      break;
      case 2:
      for (j = 0; j < b->entries; j++)
      {
        if ((sparsemap && b->lengthlist[j]) || !sparsemap)
        {
          ogg_int32_t     last = 0;
          int             lastpoint = 0;

          for (k = 0; k < b->dim; k++)
          {
            int             point;
            int             val = VFLOAT_MULTI(delta, delpoint, abs(b->quantlist[j *b->dim + k]), &point);

            val = VFLOAT_ADD(mindel, minpoint, val, point, &point);
            val = VFLOAT_ADD(last, lastpoint, val, point, &point);
            if (b->q_sequencep)
            {
              last = val;
              lastpoint = point;
            }
            if (sparsemap)
            {
              r[sparsemap[count] *b->dim + k] = val;
              rp[sparsemap[count] *b->dim + k] = point;
            }
            else 
            {
              r[count *b->dim + k] = val;
              rp[count *b->dim + k] = point;
            }
            if (*maxpoint < point)
              *maxpoint = point;
          }
          count++;
        }
      }
      break;
    }
    for (j = 0; j < n *b->dim; j++)
    if (rp[j] < *maxpoint)
      r[j] >>= *maxpoint - rp[j];
    _ogg_free(rp);
    return (r);
  }
  return (NULL);
}
void vorbis_staticbook_clear(static_codebook *b)
{       
  if (b->quantlist)
    _ogg_free(b->quantlist);
  if (b->lengthlist)
    _ogg_free(b->lengthlist);
  memset(b, 0, sizeof(*b));
}
void vorbis_staticbook_destroy(static_codebook *b)
{       
  vorbis_staticbook_clear(b);
  _ogg_free(b);
}
void vorbis_book_clear(codebook *b)
{       
         /* static book is not cleared; we're likely called on the lookup and
              the static codebook belongs to the info struct */
  if (b->valuelist)
    _ogg_free(b->valuelist);
  if (b->codelist)
    _ogg_free(b->codelist);
  if (b->dec_index)
    _ogg_free(b->dec_index);
  if (b->dec_codelengths)
    _ogg_free(b->dec_codelengths);
  if (b->dec_firsttable)
    _ogg_free(b->dec_firsttable);
  memset(b, 0, sizeof(*b));
}
static ogg_uint32_t bitreverse(ogg_uint32_t x)
{       
  x = ((x >> 16)& 0x0000ffffUL) | ((x << 16)& 0xffff0000UL);
  x = ((x >> 8)& 0x00ff00ffUL) | ((x << 8)& 0xff00ff00UL);
  x = ((x >> 4)& 0x0f0f0f0fUL) | ((x << 4)& 0xf0f0f0f0UL);
  x = ((x >> 2)& 0x33333333UL) | ((x << 2)& 0xccccccccUL);
  return ((x >> 1)& 0x55555555UL) | ((x << 1)& 0xaaaaaaaaUL);
}
static int sort32a(const void *a, const void *b)
{       
  return (* *(ogg_uint32_t * *) a > * *(ogg_uint32_t * *) b) - (* *(ogg_uint32_t * *) a < * *(ogg_uint32_t * *) b);
}
/* decode codebook arrangement is more heavily optimized than encode */
int vorbis_book_init_decode(codebook *c, const static_codebook *s)
{       
  int             i, j, n = 0, tabn;
  int             *sortindex;

  memset(c, 0, sizeof(*c));
  /* count actually used entries */
  for (i = 0; i < s->entries; i++)
    if (s->lengthlist[i] > 0)
      n++;
  c->entries = s->entries;
  c->used_entries = n;
  c->dim = s->dim;
  c->q_min = s->q_min;
  c->q_delta = s->q_delta;
  /* two different remappings go on here.  

     First, we collapse the likely sparse codebook down only to
     actually represented values/words.  This collapsing needs to be
     indexed as map-valueless books are used to encode original entry
     positions as integers.

     Second, we reorder all vectors, including the entry index above,
     by sorted bitreversed codeword to allow treeless decode. */

  {
    /* perform sort */
    ogg_uint32_t *codes = _make_words(s->lengthlist, s->entries, c->used_entries);
    ogg_uint32_t    * *codep = (ogg_uint32_t * *) alloca(sizeof(*codep) *n);

    if (codes == NULL)
      goto err_out;
    for (i = 0; i < n; i++)
    {
      codes[i] = bitreverse(codes[i]);
      codep[i] = codes + i;
    }
    qsort(codep, n, sizeof(*codep), sort32a);
    sortindex = (int *) alloca(n *sizeof(*sortindex));
    c->codelist = (ogg_uint32_t *) _ogg_malloc(n *sizeof(*c->codelist));
    /* the index is a reverse index */
    for (i = 0; i < n; i++)
    {
      int  position = codep[i] - codes;

      sortindex[position] = i;
    }
    for (i = 0; i < n; i++)
      c->codelist[sortindex[i]] = codes[i];
    _ogg_free(codes);
  }
  c->valuelist = _book_unquantize(s, n, sortindex, &c->binarypoint);
  c->dec_index = (int *) _ogg_malloc(n *sizeof(*c->dec_index));
  for (n = 0, i = 0; i < s->entries; i++)
    if (s->lengthlist[i] > 0)
      c->dec_index[sortindex[n++]] = i;
  c->dec_codelengths = (char *) _ogg_malloc(n *sizeof(*c->dec_codelengths));
  for (n = 0, i = 0; i < s->entries; i++)
    if (s->lengthlist[i] > 0)
      c->dec_codelengths[sortindex[n++]] = (unsigned char)(s->lengthlist[i]);
  c->dec_firsttablen = _ilog(c->used_entries) - 4; /* this is magic */
  if (c->dec_firsttablen < 5)
    c->dec_firsttablen = 5;
  if (c->dec_firsttablen > 8)
    c->dec_firsttablen = 8;
  tabn = 1 << c->dec_firsttablen;
  c->dec_firsttable = (ogg_uint32_t *) _ogg_calloc(tabn, sizeof(*c->dec_firsttable));
  c->dec_maxlength = 0;
  for (i = 0; i < n; i++)
  {
    if (c->dec_maxlength < c->dec_codelengths[i])
      c->dec_maxlength = c->dec_codelengths[i];
    if (c->dec_codelengths[i] <= c->dec_firsttablen)
    {
      ogg_uint32_t    orig = bitreverse(c->codelist[i]);

      for (j = 0; j < (1 << (c->dec_firsttablen - c->dec_codelengths[i])); j++)
      c->dec_firsttable[orig | (j << c->dec_codelengths[i])] = i + 1;
    }
  }
  /* now fill in 'unused' entries in the firsttable with hi/lo search
     hints for the non-direct-hits */
  {
    ogg_uint32_t    mask = 0xfffffffeUL << (31 - c->dec_firsttablen);
    long            lo = 0, hi = 0;

    for (i = 0; i < tabn; i++)
    {
      ogg_uint32_t    word = i << (32 - c->dec_firsttablen);

      if (c->dec_firsttable[bitreverse(word)] == 0)
      {
        while ((lo + 1) < n && c->codelist[lo + 1] <= word)
          lo++;
        while (hi < n && word >= (c->codelist[hi]& mask))
          hi++;
 /* we only actually have 15 bits per hint to play with here.
           In order to overflow gracefully (nothing breaks, efficiency
           just drops), encode as the difference from the extremes. */
        {
          unsigned long   loval = lo;
          unsigned long   hival = n - hi;

          if (loval > 0x7fff)
            loval = 0x7fff;
          if (hival > 0x7fff)
            hival = 0x7fff;
          c->dec_firsttable[bitreverse(word)] = 0x80000000UL | (loval << 15) | hival;
        }
      }
    }
  }
  return (0);
err_out:
  vorbis_book_clear(c);
  return (- 1);
}