static void checknumberofoccurrences(const TyrDfsstate *dfsstate,
                                     GtUword countocc,
                                     GtUword position)
{
  GtMMsearchiterator *mmsi;
  GtUword idx, bfcount;

  for (idx = 0; idx < dfsstate->mersize; idx++)
  {
    dfsstate->currentmer[idx] =
              gt_encseq_get_encoded_char(dfsstate->encseq,position+idx,
                                                dfsstate->readmode);
  }
  mmsi = gt_mmsearchiterator_new_complete_plain(dfsstate->encseq,
                                              dfsstate->suftab,
                                              0,
                                              dfsstate->totallength,
                                              0,
                                              dfsstate->readmode,
                                              dfsstate->currentmer,
                                              dfsstate->mersize);
  bfcount = gt_mmsearchiterator_count(mmsi);
  if (bfcount != countocc)
  {
    fprintf(stderr,"bfcount = "GT_WU" != "GT_WU" = countocc\n",
            bfcount,countocc);
    exit(GT_EXIT_PROGRAMMING_ERROR);
  }
  gt_mmsearchiterator_delete(mmsi);
}
extern int
gt_packedindex_chk_search(int argc, const char *argv[], GtError *err)
{
  struct chkSearchOptions params;
  Suffixarray suffixarray;
  Enumpatterniterator *epi = NULL;
  bool saIsLoaded = false;
  BWTSeq *bwtSeq = NULL;
  GtStr *inputProject = NULL;
  int parsedArgs;
  bool had_err = false;
  BWTSeqExactMatchesIterator EMIter;
  bool EMIterInitialized = false;
  GtLogger *logger = NULL;
  inputProject = gt_str_new();

  do {
    gt_error_check(err);
    {
      bool exitNow = false;
      switch (parseChkBWTOptions(&parsedArgs, argc, argv, &params,
                                 inputProject, err))
      {
      case GT_OPTION_PARSER_OK:
        break;
      case GT_OPTION_PARSER_ERROR:
        had_err = true;
        exitNow = true;
        break;
      case GT_OPTION_PARSER_REQUESTS_EXIT:
        exitNow = true;
        break;
      }
      if (exitNow)
        break;
    }
    gt_str_set(inputProject, argv[parsedArgs]);

    logger = gt_logger_new(params.verboseOutput,
                           GT_LOGGER_DEFLT_PREFIX, stdout);

    bwtSeq = gt_availBWTSeq(&params.idx.final, logger, err);
    if ((had_err = bwtSeq == NULL))
      break;

    {
      enum verifyBWTSeqErrCode retval =
        gt_BWTSeqVerifyIntegrity(bwtSeq, gt_str_get(inputProject), params.flags,
                              params.progressInterval, stderr, logger, err);
      if ((had_err = (retval != VERIFY_BWTSEQ_NO_ERROR)))
      {
        fprintf(stderr, "index integrity check failed: %s\n",
                gt_error_get(err));
        gt_error_set(err, "aborted because of index integrity check fail");
        break;
      }
    }
    if (BWTSeqHasLocateInformation(bwtSeq))
    {
      if ((had_err = !gt_initEmptyEMIterator(&EMIter, bwtSeq)))
      {
        gt_error_set(err, "Cannot create matches iterator for sequence index.");
        break;
      }
      EMIterInitialized = true;
    }
    {
      unsigned long totalLen, dbstart;
      unsigned long trial, patternLen;

      if ((had_err =
           gt_mapsuffixarray(&suffixarray, SARR_SUFTAB | SARR_ESQTAB,
                             gt_str_get(inputProject), NULL, err) != 0))
      {
        gt_error_set(err, "Can't load suffix array project with"
                  " demand for encoded sequence and suffix table files\n");
        break;
      }
      totalLen = gt_encseq_total_length(suffixarray.encseq);
      saIsLoaded = true;
      if ((had_err = (params.minPatLen >= 0L && params.maxPatLen >= 0L
                      && params.minPatLen > params.maxPatLen)))
      {
        gt_error_set(err, "Invalid pattern lengths selected: min=%ld, max=%ld;"
                  " min <= max is required.", params.minPatLen,
                  params.maxPatLen);
        break;
      }
      if (params.minPatLen < 0 || params.maxPatLen < 0)
      {
        unsigned int numofchars
          = gt_alphabet_num_of_chars(
                               gt_encseq_alphabet(suffixarray.encseq));
        if (params.minPatLen < 0)
          params.minPatLen
            = gt_recommendedprefixlength(numofchars,
                                         totalLen,
                                         GT_RECOMMENDED_MULTIPLIER_DEFAULT,
                                         true);
        if (params.maxPatLen < 0)
          params.maxPatLen =
            MAX(params.minPatLen,
                125 * gt_recommendedprefixlength(numofchars,totalLen,
                                         GT_RECOMMENDED_MULTIPLIER_DEFAULT,
                                         true)/100);
        else
          params.maxPatLen = MAX(params.maxPatLen, params.minPatLen);
      }
      fprintf(stderr, "Using patterns of lengths %lu to %lu\n",
              params.minPatLen, params.maxPatLen);
      if ((had_err = totalLen + 1 != BWTSeqLength(bwtSeq)))
      {
        gt_error_set(err, "base suffix array and index have diferrent lengths!"
                          "%lu vs. %lu",  totalLen + 1,
                  BWTSeqLength(bwtSeq));
        break;
      }
      if ((had_err =
           (epi = gt_newenumpatterniterator(params.minPatLen, params.maxPatLen,
                                         suffixarray.encseq,
                                         err)) == NULL))
      {
        fputs("Creation of pattern iterator failed!\n", stderr);
        break;
      }
      for (trial = 0; !had_err && trial < params.numOfSamples; ++trial)
      {
        const GtUchar *pptr = gt_nextEnumpatterniterator(&patternLen, epi);
        GtMMsearchiterator *mmsi =
          gt_mmsearchiterator_new_complete_olain(suffixarray.encseq,
                                            suffixarray.suftab,
                                            0,  /* leftbound */
                                            totalLen, /* rightbound */
                                            0, /* offset */
                                            suffixarray.readmode,
                                            pptr,
                                            patternLen);
        if (BWTSeqHasLocateInformation(bwtSeq))
        {
          if ((had_err = !gt_reinitEMIterator(&EMIter, bwtSeq, pptr, patternLen,
                                           false)))
          {
            fputs("Internal error: failed to reinitialize pattern match"
                  " iterator", stderr);
            abort();
          }
          gt_assert(gt_EMINumMatchesTotal(&EMIter) ==
                    gt_BWTSeqMatchCount(bwtSeq, pptr, patternLen,
                                        false));
          gt_assert(gt_EMINumMatchesTotal(&EMIter)
                      == gt_mmsearchiterator_count(mmsi));
          while (gt_mmsearchiterator_next(&dbstart,mmsi))
          {
            unsigned long matchPos = 0;
            bool match = EMIGetNextMatch(&EMIter, &matchPos, bwtSeq);
            if ((had_err = !match))
            {
              gt_error_set(err,
                           "matches of packedindex expired before mmsearch!");
              break;
            }
            if ((had_err = matchPos != dbstart))
            {
              gt_error_set(err, "packedindex match doesn't equal mmsearch "
                           "match result!\n%lu vs. %lu\n",
                           matchPos, dbstart);
            }
          }
          if (!had_err)
          {
            unsigned long matchPos;
            bool trailingMatch = EMIGetNextMatch(&EMIter, &matchPos, bwtSeq);
            if ((had_err = trailingMatch))
            {
              gt_error_set(err, "matches of mmsearch expired before fmindex!");
              break;
            }
          }
        }
        else
        {
          unsigned long numFMIMatches = gt_BWTSeqMatchCount(bwtSeq, pptr,
                                                         patternLen,
                                                         false),
            numMMSearchMatches = gt_mmsearchiterator_count(mmsi);
          if ((had_err = numFMIMatches != numMMSearchMatches))
          {
            gt_error_set(err, "Number of matches not equal for suffix array ("
                              "%lu) and fmindex (%lu).\n",
                      numFMIMatches, numMMSearchMatches);
          }
        }
        gt_mmsearchiterator_delete(mmsi);
        mmsi = NULL;
        if (params.progressInterval && !((trial + 1) % params.progressInterval))
          putc('.', stderr);
      }
      if (params.progressInterval)
        putc('\n', stderr);
      fprintf(stderr, "Finished %lu of %lu matchings successfully.\n",
              trial, params.numOfSamples);
    }
  } while (0);
  if (EMIterInitialized) gt_destructEMIterator(&EMIter);
  if (saIsLoaded) gt_freesuffixarray(&suffixarray);
  gt_freeEnumpatterniterator(epi);
  if (bwtSeq) gt_deleteBWTSeq(bwtSeq);
  if (logger) gt_logger_delete(logger);
  if (inputProject) gt_str_delete(inputProject);
  return had_err?-1:0;
}