source: main/trunk/greenstone2/common-src/indexers/mgpp/text/mgpp_compression_dict.cpp@ 26294

/**************************************************************************
 *
 * mgpp_compression_dict.cpp -- Routines for creating compression dictionary
 * Copyright (C) 1994  Neil Sharman
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 **************************************************************************/

#define _XOPEN_SOURCE 1
// This was added for Solaris, but it makes things worse on Solaris for me...
// #define _XOPEN_SOURCE_EXTENDED 1

// need this to avoid bizarre compiler problems under VC++ 6.0
#if defined (__WIN32__) && !defined (GSDL_USE_IOS_H)
# include <iostream>
#endif

/* getopt is in posix.2, so cygwin should have it in unistd, but doesn't */
#if defined (__WIN32__) || defined (__CYGWIN__)
# include "getopt_old.h"
#else
# include <unistd.h>
#endif

#include "sysfuncs.h"
#include "memlib.h"
#include "messages.h"
#include "local_strings.h"
#include "bitio_gen.h"
#include "bitio_m_stdio.h"
#include "mgheap.h"
#include "netorder.h"  /* [RPAP - Jan 97: Endian Ordering] */

#include "mg_files.h"
#include "locallib.h"
#include "invf.h"
#include "text.h"
#include "words.h"
#include "mg.h"
#include "WordData.h"

#define MAXBITS (sizeof(mg_u_long) * 8)

#define is_power_of_two(a) ((a) != 0 && (((a) & ((a)-1)) == 0))

#define MAX_RECALCULATIONS 100

typedef struct DictWordData : public WordData
  {
    float saving;
    float char_bit_cost;
    mg_u_long num_trans;
    u_char *word;
  }
DictWordData;

static DictWordData *Words[2];
static mg_u_long Num[2];
static mg_u_long chars[2];

#define KIND(p) (((p) >= Words[0] && (p) < Words[0] + Num[0]) ? 0 : 1)
#define IsWord(p) (((p) >= Words[1] && (p) < Words[1] + Num[1]) ? 1 : 0)
#define IsNonWord(p) (((p) >= Words[0] && (p) < Words[0] + Num[0]) ? 1 : 0)


typedef struct DictData
  {
    DictWordData **wd;
    mg_u_long num_wds;
    mg_u_long chars;
  }
DictData;

typedef DictData DictInfo[2];

static DictInfo keep, discard, all;
static compression_stats_header csh;

static char *file_name = (char*)"";
static mg_u_long novel_method = MG_NOVEL_HUFFMAN_CHARS;


static void ReadInWords (char *);
static void Select_on (int k, heap_comp hc);
static void Method3 (int k);
static void Select_all (void);
static mg_u_long WriteOutWords (char *, mg_u_long, int);
static int DecFreqIncWL (void *a, void *b);
static int OccuranceOrder (void *a, void *b);



int main (int argc, char **argv)
{
  int ch;
  char type = 'C';
  char mode = '0';
  int lookback = 2;
  double k = 0;
  mg_u_long mem_reqd;
  opterr = 0;
  msg_prefix = argv[0];
  while ((ch = getopt (argc, argv, "0123CPSf:d:l:hk:HDY")) != -1)
    switch (ch)
      {
      case 'H':
    novel_method = MG_NOVEL_HUFFMAN_CHARS;
    break;
      case 'D':
    novel_method = MG_NOVEL_DELTA;
    break;
      case 'Y':
    novel_method = MG_NOVEL_HYBRID;
    break;
      case 'f':     /* input file */
    file_name = optarg;
    break;
      case 'd':
    set_basepath (optarg);
    break;
      case 'C':
      case 'P':
      case 'S':
    type = ch;
    break;
      case '0':
      case '1':
      case '2':
      case '3':
    mode = ch;
    break;
      case 'l':
    lookback = atoi (optarg);
    if (!is_power_of_two (lookback))
      FatalError (1, "The lookback value must be a power of 2");
    lookback = floorlog_2 (lookback);
    break;
      case 'k':
    k = atof (optarg) * 1024;
    break;
      case 'h':
      case '?':
    fprintf (stderr, "usage: %s [-l lookback] [-f input_file]"
    "[-d data directory] [-h] [-0|-1|-2|-3] [-C|-P|-S] [-k mem (Kb)]\n",
         argv[0]);
    exit (1);
      }

  ReadInWords (file_name);

  if (type == 'C')
    {
      Select_all ();
      mem_reqd = WriteOutWords (file_name, MG_COMPLETE_DICTIONARY, lookback);
    }
  else
    {
      switch (mode)
    {
    case '0':
      Select_all ();
      break;
    case '1':
#ifndef SILENT
      Message ("Dictionary limit of %.2f Kb", k / 1024);
#endif
      Select_on ((int) k, OccuranceOrder);
      break;
    case '2':
#ifndef SILENT
      Message ("Dictionary limit of %.2f Kb", k / 1024);
#endif
      Select_on ((int) k, DecFreqIncWL);
      break;
    case '3':
#ifndef SILENT
      Message ("Dictionary limit of %.2f Kb", k / 1024);
#endif
      Method3 ((int) k);
      break;
    }
      if (type == 'P')
    {
      mem_reqd = WriteOutWords (file_name, MG_PARTIAL_DICTIONARY, lookback);
    }
      else
    {
      mem_reqd = WriteOutWords (file_name, MG_SEED_DICTIONARY, lookback);
    }
    }

#ifndef SILENT
  Message ("Num words           : %8u -> %8u\n", Num[1], keep[1].num_wds);
  Message ("Num non-words       : %8u -> %8u\n", Num[0], keep[0].num_wds);
  Message ("Chars of words      : %8u -> %8u\n", chars[1], keep[1].chars);
  Message ("Chars of non-words  : %8u -> %8u\n", chars[0], keep[0].chars);
  Message ("Mem usage           : %8u -> %8u\n",
       (Num[0] + Num[1]) * sizeof (char *) + chars[0] + chars[1],
         (keep[0].num_wds + keep[1].num_wds) * sizeof (char *) +
       keep[0].chars + keep[1].chars);
  Message ("Actual mem required : %8u\n", mem_reqd);
#endif
  return (0);
}




static void 
ReadInWords (char *filename)
{
  FILE *f;
  mg_u_long i;
  f = open_file (filename, TEXT_STATS_DICT_SUFFIX, "rb",
         MAGIC_STATS_DICT, MG_ABORT);  /* [RPAP - Feb 97: WIN32 Port] */

  fread (&csh, sizeof (csh), 1, f);

  /* [RPAP - Jan 97: Endian Ordering] */
  NTOHUL(csh.num_docs);
  NTOHD(csh.num_bytes);

  for (i = 0; i < 2; ++i)
    {
      frags_stats_header fsh;
      char *buf;
      DictWordData *wd;
      chars[i] = 0;

      fread (&fsh, sizeof (fsh), 1, f);
      /* [RPAP - Jan 97: Endian Ordering] */
      NTOHUL(fsh.num_frags);
      NTOHUL(fsh.mem_for_frags);

      Num[i] = all[i].num_wds = fsh.num_frags;

      /* The +1 on the following line is to leave room for the esc code. */
      all[i].wd = (DictWordData **) Xmalloc (sizeof (DictWordData *) * Num[i] + 1);

      buf = (char *) Xmalloc (fsh.mem_for_frags);
      wd = Words[i] = (DictWordData *) Xmalloc (sizeof (DictWordData) * Num[i]);
      unsigned int j;
      for (j = 0; j < Num[i]; ++j, ++wd)
    {
      int len;

      // read docCount and wordCount
      wd->read(f);

      // read an mgString
      len = fgetc (f);
      wd->word = (u_char *) buf;
      *buf++ = len;
      fread (buf, len, 1, f);
      buf += len;
      all[i].wd[j] = wd;
    }
      chars[i] = fsh.mem_for_frags - fsh.num_frags;
    }
  fclose (f);
}


static void 
Alloc_keep_discard (void)
{
  keep[0].num_wds = 0;
  keep[0].wd = (DictWordData **) Xmalloc ((Num[0] + 1) * sizeof (DictWordData *));
  keep[1].num_wds = 0;
  keep[1].wd = (DictWordData **) Xmalloc ((Num[1] + 1) * sizeof (DictWordData *));
  discard[0].num_wds = 0;
  discard[0].wd = (DictWordData **) Xmalloc ((Num[0] + 1) * sizeof (DictWordData *));
  discard[1].num_wds = 0;
  discard[1].wd = (DictWordData **) Xmalloc ((Num[1] + 1) * sizeof (DictWordData *));
}


static int 
sort_comp (const void *a, const void *b)
{
  DictWordData *aa = *(DictWordData **) a;
  DictWordData *bb = *(DictWordData **) b;
  return casecompare (aa->word, bb->word);  /* [RPAP - Jan 97: Stem Index Change] */
}



static void 
SortAndCount_DictData (DictData * dd)
{
  unsigned int i;
  DictWordData **wd;
  qsort (dd->wd, dd->num_wds, sizeof (DictWordData *), sort_comp);
  dd->chars = 0;
  wd = dd->wd;
  for (i = 0; i < dd->num_wds; ++i, ++wd)
    dd->chars += (*wd)->word[0];
}


static void 
Select_all (void)
{
  unsigned int i;
  Alloc_keep_discard ();
  keep[0].num_wds = Num[0];
  for (i = 0; i < Num[0]; ++i)
    keep[0].wd[i] = Words[0] + i;
  keep[1].num_wds = Num[1];
  for (i = 0; i < Num[1]; ++i)
    keep[1].wd[i] = Words[1] + i;
  SortAndCount_DictData (&keep[0]);
  SortAndCount_DictData (&keep[1]);
}




static int 
DecFreqIncWL (void *a, void *b)
{
  DictWordData *aa = *(DictWordData **) a;
  DictWordData *bb = *(DictWordData **) b;
  if (aa->docCount > bb->docCount)
    return -1;
  else if (aa->docCount < bb->docCount)
    return 1;
  else
    return bb->word[0] - aa->word[0];
}


static int 
OccuranceOrder (void *a, void *b)
{
  DictWordData *aa = *(DictWordData **) a;
  DictWordData *bb = *(DictWordData **) b;
  if (aa->words() > bb->words())
    return 1;
  else if (aa->words() < bb->words())
    return -1;
  else
    return 0;
}


static void 
Select_on (int k, heap_comp hc)
{
  int i, num, mem;
  DictWordData **wd;

  Alloc_keep_discard ();

  num = Num[0] + Num[1];
  wd = (DictWordData **) Xmalloc (num * sizeof (DictWordData *));
  for (i = 0; (unsigned int)i < Num[0]; ++i)
    wd[i] = Words[0] + i;
  for (i = 0; (unsigned int)i < Num[1]; ++i)
    wd[i + Num[0]] = Words[1] + i;

  heap_build (wd, sizeof (*wd), num, hc);

  mem = 0;
  while (k > mem && num)
    {
      int idx;
      DictWordData *word = wd[0];
#ifdef DEBUG
      fprintf (stderr, "%4d:%4d:%8d :%8d :%8d : \"%s\"\n",
           keep[0].num_wds, keep[1].num_wds,
           mem, word->documents(), word->word, word2str (word->word));
#endif
      mem += sizeof (u_char *) + word->word[0];
      heap_deletehead (wd, sizeof (*wd), &num, hc);
      idx = KIND (word);
      keep[idx].wd[keep[idx].num_wds++] = word;
    }

  for (i = 0; i < num; ++i)
    {
      DictWordData *word = wd[i];
      int idx = KIND (word);
      discard[idx].wd[discard[idx].num_wds++] = word;
    }
  SortAndCount_DictData (&keep[0]);
  SortAndCount_DictData (&keep[1]);
  SortAndCount_DictData (&discard[0]);
  SortAndCount_DictData (&discard[1]);

  assert (keep[0].num_wds + discard[0].num_wds == Num[0]);
  assert (keep[1].num_wds + discard[1].num_wds == Num[1]);

}



static int 
BigSaving (void *a, void *b)
{
  DictWordData *aa = *(DictWordData **) a;
  DictWordData *bb = *(DictWordData **) b;
  return (aa->saving > bb->saving) ? -1 : (aa->saving < bb->saving);
}

static int 
SmallSaving (void *a, void *b)
{
  DictWordData *aa = *(DictWordData **) a;
  DictWordData *bb = *(DictWordData **) b;
  return (aa->saving < bb->saving) ? -1 : (aa->saving > bb->saving);
}


static void 
CalcCharCounts (DictWordData ** wd, int num,
        char *char_lens[2], char *len_lens[2],
        mg_u_long escape[2])
{
  mg_s_long char_freqs[2][256];
  mg_s_long len_freqs[2][16];
  huff_data hd;
  int i;
  escape[0] = 0;
  escape[1] = 0;
  memset (char_freqs, '\0', sizeof (char_freqs));
  memset (len_freqs, '\0', sizeof (len_freqs));
  for (i = 0; i < num; ++i, ++wd)
    {
      mg_u_long freq = (*wd)->documents();
      u_char *buf = (*wd)->word;
      int len = *buf++;
      int idx = KIND (*wd);
      len_freqs[idx][len] += freq;
      escape[idx] += freq;
      for (; len; --len, ++buf)
    char_freqs[idx][(mg_u_long) (*buf)] += freq;
    }
  Generate_Huffman_Data (256, char_freqs[0], &hd, NULL);
  char_lens[0] = hd.clens;
  Generate_Huffman_Data (256, char_freqs[1], &hd, NULL);
  char_lens[1] = hd.clens;

  Generate_Huffman_Data (16, len_freqs[0], &hd, NULL);
  len_lens[0] = hd.clens;
  Generate_Huffman_Data (16, len_freqs[1], &hd, NULL);
  len_lens[1] = hd.clens;
}





inline void CalcBitCostForWordData(DictWordData **word, int num,
                   double freqs_trans[2], mg_u_long escape[2],
                   char * char_lens[2], char *len_lens[2], 
                   double esc[2], int num_trans)
{ 
  int j;

  for (j = 0; j < num; ++j, ++word)
    {
      float   cbc, wbc;
      u_char *buf = (*word)->word;
      int     len = *buf++;
      mg_u_long  freq = (*word)->documents();
      int     idx = KIND (*word);

      cbc = len_lens[idx][len];
      for (; len; --len, ++buf)
    cbc += char_lens[idx][(mg_u_long) (*buf)];

      (*word)->char_bit_cost = (cbc + esc[idx]) * freq;

      wbc = -log2 (freq / (freqs_trans[idx] + escape[idx])) * freq;

      (*word)->saving = ((*word)->char_bit_cost - wbc) /
    (sizeof (char *) + (*word)->word[0]);

      (*word)->num_trans = num_trans;
    }
}



void 
CalcBitCost (DictWordData ** discard_word, int discard_num,
         DictWordData ** keep_word, int keep_num, double freqs_trans[2],
         mg_u_long escape[2], int num_trans)
{
  char *char_lens[2];
  char *len_lens[2];
  double esc[2];
  CalcCharCounts (discard_word, discard_num, char_lens, len_lens, escape);
  esc[0] = -log2 (escape[0] / (freqs_trans[0] + escape[0]));
  esc[1] = -log2 (escape[1] / (freqs_trans[1] + escape[1]));
  CalcBitCostForWordData(discard_word, discard_num, freqs_trans, escape,
             char_lens, len_lens, esc, num_trans);
  CalcBitCostForWordData(keep_word, keep_num, freqs_trans, escape,
             char_lens, len_lens, esc, num_trans);
  Xfree (char_lens[0]);
  Xfree (char_lens[1]);
  Xfree (len_lens[0]);
  Xfree (len_lens[1]);
}

inline void m3_transferWord(DictWordData **toHeap, int *toNum, heap_comp toSaving,
                DictWordData **fromHeap, int *fromNum, heap_comp fromSaving,
                int *num_trans, double freqs_trans[], int *mem, double *total,
                int *count)
{
  /* Transfer the word at the top of the keep heap to the
     discard heap. */
  DictWordData *word = fromHeap[0];
  int idx = KIND (word);
  heap_deletehead (fromHeap, sizeof (word), fromNum, fromSaving);
  toHeap[*toNum] = word;
  heap_additem (toHeap, sizeof (word), toNum, toSaving);
  freqs_trans[idx] -= word->documents();
  *mem = (*mem) - sizeof (u_char *) + word->word[0];
  *num_trans += 1;
  *total += word->saving;
  *count += 1;
#ifdef DEBUG
  fprintf (stderr,
       "KEEP -> DISCARD %8d :%8d :%8.0f :%8.0f : \"%s\"\n",
       *mem, word->documents(), word->char_bit_cost,
       word->saving, word2str (word->word));
#endif
}

inline void m3_storeWord(DictWordData **wordHeap, int wordNum, int num_trans, 
             double freqs_trans[], mg_u_long escape[], heap_comp hc)
{
  DictWordData *word = wordHeap[0];
  int idx = KIND (word);
  float wbc;
#ifdef DEBUG1
  fprintf (stderr, "KEEP \"%s\" %.2f ->", word2str (word->word),
       word->saving);
#endif
  wbc = -log2 (word->documents() / (freqs_trans[idx] + escape[idx])) *
    word->documents();
  word->saving = (word->char_bit_cost - wbc) /
    (sizeof (char *) + word->word[0]);
#ifdef DEBUG1
  fprintf (stderr, " %.2f\n", word->saving);
#endif
  word->num_trans = num_trans;
  heap_changedhead (wordHeap, sizeof (word), wordNum, hc);
}


static void 
Method3 (int k)
{
  int i, keep_num, discard_num, mem, num_trans, recalc_reqd;
  int keep_to_discard = 0;
  int discard_to_keep = 0;
  int recalcs = 0;
  double freqs_trans[2], total;
  mg_u_long escape[2];
  DictWordData **keep_heap, **discard_heap;

  freqs_trans[0] = freqs_trans[1] = 0;
  num_trans = 0;

  discard_num = Num[0] + Num[1];
  discard_heap = (DictWordData **) Xmalloc (discard_num * sizeof (DictWordData *));

  keep_num = 0;
  keep_heap = (DictWordData **) Xmalloc (discard_num * sizeof (DictWordData *));


  for (i = 0; (unsigned int)i < Num[0]; ++i)
    discard_heap[i] = Words[0] + i;
  for (i = 0; (unsigned int)i < Num[1]; ++i)
    discard_heap[i + Num[0]] = Words[1] + i;

  heap_build (discard_heap, sizeof (*discard_heap), discard_num, DecFreqIncWL);

  mem = 0;
  while (k > mem && discard_num)
    {
      DictWordData *word = discard_heap[0];
      mem += sizeof (u_char *) + word->word[0];
      heap_deletehead (discard_heap, sizeof (word), &discard_num, DecFreqIncWL);
      keep_heap[keep_num++] = word;
      freqs_trans[KIND (word)] += word->documents();
      ++num_trans;
    }

  CalcBitCost (discard_heap, discard_num, keep_heap, keep_num,
           freqs_trans, escape, num_trans);
  heap_build (discard_heap, sizeof (*discard_heap), discard_num, BigSaving);
  heap_build (keep_heap, sizeof (*keep_heap), keep_num, SmallSaving);

  total = 0;
  recalc_reqd = 0;
  while (keep_num && discard_num)
    {
      if ((keep_num && keep_heap[0]->num_trans < (unsigned)num_trans) ||
      (discard_num && discard_heap[0]->num_trans < (unsigned)num_trans))
    {
      if (keep_num && keep_heap[0]->num_trans < (unsigned)num_trans)
        {
          m3_storeWord(keep_heap, keep_num, num_trans, freqs_trans, escape, SmallSaving);
        }

      if (discard_num && discard_heap[0]->num_trans < (unsigned)num_trans)
        {
          m3_storeWord(discard_heap, discard_num, num_trans, freqs_trans, escape, BigSaving);
        }
    }
      else if (keep_heap[0]->saving < discard_heap[0]->saving)
    {
      assert (keep_num && discard_num);
      if (keep_num && mem + sizeof (char *) + discard_heap[0]->word[0] > (unsigned)k)
        {
          /* Transfer the word at the top of the keep heap to the
             discard heap. */
          m3_transferWord(discard_heap, &discard_num, BigSaving,
                  keep_heap, &keep_num, SmallSaving,
                  &num_trans, freqs_trans, &mem, &total, &keep_to_discard);
        }
      else
        {
          /* Transfer the word at the top of the discard heap to the
             keep heap. */
          m3_transferWord(keep_heap, &keep_num, SmallSaving,
                  discard_heap, &discard_num, BigSaving,
                  &num_trans, freqs_trans, &mem, &total, &discard_to_keep);
        }

      recalc_reqd = 1;

    }
      else
    {
      if (recalc_reqd == 0)
        break;
#ifdef DEBUG1
      fprintf (stderr, "--------------\n");
#endif
      if (recalcs == MAX_RECALCULATIONS)
        break;
      CalcBitCost (discard_heap, discard_num, keep_heap, keep_num,
               freqs_trans, escape, num_trans);
      heap_build (discard_heap, sizeof (*discard_heap),
              discard_num, BigSaving);
      heap_build (keep_heap, sizeof (keep_heap), keep_num, SmallSaving);
      recalc_reqd = 0;
      ++recalcs;
    }
    }

  Alloc_keep_discard ();

  for (i = 0; i < discard_num; ++i)
    {
      DictWordData *word = discard_heap[i];
      int idx = KIND (word);
      assert (IsWord (word) || IsNonWord (word));
      discard[idx].wd[discard[idx].num_wds++] = word;
    }
  for (i = 0; i < keep_num; ++i)
    {
      DictWordData *word = keep_heap[i];
      int idx = KIND (word);
      assert (IsWord (word) || IsNonWord (word));
      keep[idx].wd[keep[idx].num_wds++] = word;
    }
  SortAndCount_DictData (&keep[0]);
  SortAndCount_DictData (&keep[1]);
  SortAndCount_DictData (&discard[0]);
  SortAndCount_DictData (&discard[1]);

  assert (keep[0].num_wds + discard[0].num_wds == Num[0]);
  assert (keep[1].num_wds + discard[1].num_wds == Num[1]);
#ifndef SILENT
  Message ("Keep -> Discard        : %8d", keep_to_discard);
  Message ("Discard -> Keep        : %8d", discard_to_keep);
  Message ("Huffman Recalculations : %8d", recalcs);
  if (recalcs == MAX_RECALCULATIONS)
    Message ("WARNING: The number of recalculations == %d", MAX_RECALCULATIONS);
#endif
}










/****************************************************************************
 *****                                  *****
 *****          Dictionary saving code              *****
 *****                                  *****
 ****************************************************************************/



static void 
Write_cdh (FILE * f, compression_dict_header * cdh)
{
  /* [RPAP - Jan 97: Endian Ordering] */
  int i;
  compression_dict_header tmp = *cdh;
  HTONUL(tmp.dict_type);
  HTONUL(tmp.novel_method);
  for (i = 0; i < TEXT_PARAMS; ++i)
    HTONUL(tmp.params[i]);
  HTONUL(tmp.num_words[0]);
  HTONUL(tmp.num_words[1]);
  HTONUL(tmp.num_word_chars[0]);
  HTONUL(tmp.num_word_chars[1]);
  HTONUL(tmp.lookback);

  fwrite (&tmp, sizeof (tmp), 1, f);
}


static void 
Write_words (FILE * f, DictData * dd)
{
  unsigned int i;
  u_char *curr, *prev = NULL;
  for (i = 0; i < dd->num_wds; ++i)
    {
      int len;
      curr = dd->wd[i]->word;
      if (prev)
    /* look for prefix match with prev string */
    len = prefixlen (prev, curr);
      else
    len = 0;
      fputc ((len << 4) + (curr[0] - len), f);
      fwrite (curr + len + 1, sizeof (u_char), curr[0] - len, f);
      prev = curr;
    }

}


static int 
Uncompressed_size (DictData * dd)
{
  unsigned int i, us;
  for (us = i = 0; i < dd->num_wds; ++i)
    us += dd->wd[i]->word[0];
  return us;
}


static mg_u_long 
Write_data (FILE * f, DictData * dd, int lookback)
{
  mg_u_long mem_reqd;
  huff_data *hd;
  int i; 
  mg_u_long us = dd->num_wds;
  mg_s_long *freqs;
  mg_u_long huff_words_size[MAX_HUFFCODE_LEN + 1];
  mg_u_long lencounts[MAX_HUFFCODE_LEN + 1];
  u_char *lastword[MAX_HUFFCODE_LEN + 1];

  if (!(freqs = new mg_s_long [dd->num_wds]))
    FatalError (1, "Unable to allocate memory for freqs");

  for (i = 0; (unsigned)i < dd->num_wds; ++i)
    {
      freqs[i] = dd->wd[i]->documents();
      us += dd->wd[i]->word[0];
    }

  if (!(hd = Generate_Huffman_Data (dd->num_wds, freqs, NULL, NULL)))
    FatalError (1, "Unable to allocate memory for huffman data");

  delete []freqs;
  freqs = NULL;

  if (Write_Huffman_Data (f, hd) == -1)
    FatalError (1, "Unable to write huffman data");

  HTONUL(us);  /* [RPAP - Jan 97: Endian Ordering] */
  fwrite (&us, sizeof (us), 1, f);
  NTOHUL(us);  /* [RPAP - Jan 97: Endian Ordering] */


/* Calculate the amount of memory that will be required to store the text for
   each different huffman code len. Every 1<<lookback words for each different
   codelen length will not be prefixed by previous strings. */


  memset (&huff_words_size, '\0', sizeof (huff_words_size));
  memset (&lencounts, '\0', sizeof (lencounts));

  mem_reqd = 0;

  for (i = 0; (unsigned)i < dd->num_wds; ++i)
    {
      int codelen = hd->clens[i];
      u_char *word = dd->wd[i]->word;

      if (!codelen)
    FatalError (1, "The length of a code for a word was zero");

      huff_words_size[codelen] += word[0] + 1;
      mem_reqd += word[0] + (lookback != 0);
#if 0
      if ((lencounts[codelen] & ((1 << lookback) - 1)) == 0)
    lastword[codelen] = word;
      else
    huff_words_size[codelen] -= prefixlen (lastword[codelen], word);
#else
      if ((lencounts[codelen] & ((1 << lookback) - 1)) != 0)
    {
      int save = prefixlen (lastword[codelen], word);
      mem_reqd -= save;
      huff_words_size[codelen] -= save;
    }
      else
    {
      mem_reqd += sizeof (u_char *);
    }
      lastword[codelen] = word;
#endif
      ++lencounts[codelen];
    }

  /* [RPAP - Jan 97: Endian Ordering] */
  for (i = hd->mincodelen; i < hd->maxcodelen + 1; ++i)
    HTONUL(huff_words_size[i]);

  fwrite (huff_words_size + hd->mincodelen, sizeof (*huff_words_size),
      hd->maxcodelen - hd->mincodelen + 1, f);

  /* [RPAP - Jan 97: Endian Ordering] */
  for (i = hd->mincodelen; i < hd->maxcodelen + 1; ++i)
    NTOHUL(huff_words_size[i]);

  Write_words (f, dd);

  delete []hd->clens;
  delete hd;

  return mem_reqd;
}



static void 
Write_charfreqs (FILE * f, DictData * dd, int words,
         int zero_freq_permitted)
{
  unsigned int j;
  mg_s_long freqs[256];
  DictWordData **wd = dd->wd;
  huff_data *hd;

  memset (freqs, '\0', sizeof (freqs));

  for (j = 0; j < dd->num_wds; ++j, ++wd)
    {
      u_char *buf = (*wd)->word;
      int len = *buf++;
      for (; len; --len, ++buf)
    freqs[(mg_u_long) (*buf)] += (*wd)->documents();
    }

  if (!zero_freq_permitted)
    for (j = 0; j < 256; ++j)
      if (!freqs[j] && PESINAWORD (j) == words)
    freqs[j] = 1;

  if (!(hd = Generate_Huffman_Data (256, freqs, NULL, NULL)))
    FatalError (1, "Unable to allocate memory for huffman data");

  if (Write_Huffman_Data (f, hd) == -1)
    FatalError (1, "Unable to write huffman data");

  delete []hd->clens;
  delete hd;
}




static void 
Write_wordlens (FILE * f, DictData * dd, int zero_freq_permitted)
{
  unsigned int j;
  mg_s_long freqs[16];
  DictWordData **wd = dd->wd;
  huff_data *hd;

  memset (freqs, '\0', sizeof (freqs));

  for (j = 0; j < dd->num_wds; ++j, ++wd)
    freqs[(*wd)->word[0]] += (*wd)->documents();

  if (!zero_freq_permitted)
    for (j = 0; j < 16; ++j)
      if (!freqs[j])
    freqs[j] = 1;

  if (!(hd = Generate_Huffman_Data (16, freqs, NULL, NULL)))
    FatalError (1, "Unable to allocate memory for huffman data");

  if (Write_Huffman_Data (f, hd) == -1)
    FatalError (1, "Unable to write huffman data");


  delete []hd->clens;
  delete hd;
}



static mg_u_long 
WriteOutWords (char *file_name, mg_u_long type, int lookback)
{
  FILE *f;
  int i;
  mg_u_long mem_reqd = 0;

  compression_dict_header cdh;
  f = create_file (file_name, TEXT_DICT_SUFFIX, "w+b",
           MAGIC_DICT, MG_ABORT);  /* [RPAP - Feb 97: WIN32 Port] */

  memset (&cdh, '\0', sizeof(cdh));

  cdh.dict_type = type;
  cdh.novel_method = (type == MG_SEED_DICTIONARY) ? novel_method :
    MG_NOVEL_HUFFMAN_CHARS;

  cdh.num_words[1] = keep[1].num_wds;
  cdh.num_words[0] = keep[0].num_wds;
  cdh.num_word_chars[1] = Uncompressed_size (&keep[1]);
  cdh.num_word_chars[0] = Uncompressed_size (&keep[0]);
  cdh.lookback = lookback;

  Write_cdh (f, &cdh);

  for (i = 0; i < 2; ++i)
    switch (type)
      {
      case MG_COMPLETE_DICTIONARY:
    {
      mem_reqd += Write_data (f, &keep[i], lookback);
    }
    break;
      case MG_PARTIAL_DICTIONARY:
    {
      if (keep[i].num_wds)
        {
          int j;
          DictWordData esc;
          esc.docCount = 0;
          esc.word = (u_char *) "";
          keep[i].wd[keep[i].num_wds++] = &esc;
          for (j = 0; (unsigned)j < discard[i].num_wds; ++j)
        esc.docCount += discard[i].wd[j]->documents();
          if (!esc.docCount)
        ++esc.docCount;
          mem_reqd += Write_data (f, &keep[i], lookback);
        }
      Write_charfreqs (f, &discard[i], i, 1);
      Write_wordlens (f, &discard[i], 1);
    }
    break;
      case MG_SEED_DICTIONARY:
    {
      if (keep[i].num_wds)
        {
          int j;
          DictWordData esc;
          esc.docCount = 0;
          esc.word = (u_char *) "";
          keep[i].wd[keep[i].num_wds++] = &esc;
          for (j = 0; (unsigned)j < all[i].num_wds; ++j)
        if (all[i].wd[j]->documents() == 1)
          ++esc.docCount;
          if (!esc.docCount)
        ++esc.docCount;
          mem_reqd += Write_data (f, &keep[i], lookback);
        }
      switch (novel_method)
        {
        case MG_NOVEL_HUFFMAN_CHARS:
          Write_charfreqs (f, &all[i], i, 0);
          Write_wordlens (f, &all[i], 0);
          break;
        case MG_NOVEL_DELTA:
          break;
        case MG_NOVEL_HYBRID:
          break;
        default:
          FatalError (1, "Bad novel method");
        }
    }
    break;
      }
  fclose (f);
  return mem_reqd;
}