/*
 * Copyright (c) 1997-2006  Motoyuki Kasahara
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "build-pre.h"
#include "eb.h"
#include "error.h"
#include "text.h"
#include "build-post.h"

/*
 * Page-ID macros.
 */
#define PAGE_ID_IS_LEAF_LAYER(page_id)        (((page_id) & 0x80) == 0x80)
#define PAGE_ID_IS_LAYER_START(page_id)        (((page_id) & 0x40) == 0x40)
#define PAGE_ID_IS_LAYER_END(page_id)        (((page_id) & 0x20) == 0x20)
#define PAGE_ID_HAVE_GROUP_ENTRY(page_id)    (((page_id) & 0x10) == 0x10)

/*
 * The maximum number of hit entries for tomporary hit lists.
 * This is used in eb_hit_list().
 */
#define EB_TMP_MAX_HITS        64

/*
 * Book-code of the book in which you want to search a word.
 */
static EB_Book_Code cache_book_code = EB_BOOK_NONE;

/*
 * Cache buffer for the current page.
 */
static char cache_buffer[EB_SIZE_PAGE];

/*
 * Cache buffer for the current page.
 */
static int cache_page;

/*
 * Mutex for cache variables.
 */
#ifdef ENABLE_PTHREAD
static pthread_mutex_t cache_mutex = PTHREAD_MUTEX_INITIALIZER;
#endif

/*
 * Unexported functions.
 */
static EB_Error_Code eb_hit_list_word(EB_Book *book,
  EB_Search_Context *context, int max_hit_count, EB_Hit *hit_list,
  int *hit_count);
static EB_Error_Code eb_hit_list_keyword(EB_Book *book,
  EB_Search_Context *context, int max_hit_count, EB_Hit *hit_list,
  int *hit_count);
static EB_Error_Code eb_hit_list_multi(EB_Book *book,
  EB_Search_Context *context, int max_hit_count, EB_Hit *hit_list,
  int *hit_count);
static void eb_and_hit_lists(EB_Hit and_list[EB_TMP_MAX_HITS],
  int *and_count, int max_and_count, int hit_list_count,
  EB_Hit hit_lists[EB_NUMBER_OF_SEARCH_CONTEXTS][EB_TMP_MAX_HITS],
  int hit_counts[EB_NUMBER_OF_SEARCH_CONTEXTS]);


/*
 * Intialize search contexts of `book'.
 */
void
eb_initialize_search_contexts(EB_Book *book)
{
  EB_Search_Context *context;
  int i;

  LOG(("in: eb_initialize_search_context(book=%d)", (int)book->code));

  for (i = 0, context = book->search_contexts;
     i < EB_NUMBER_OF_SEARCH_CONTEXTS; i++, context++) {
    context->code = EB_SEARCH_NONE;
    context->compare_pre = NULL;
    context->compare_single = NULL;
    context->compare_group = NULL;
    context->comparison_result = -1;
    context->word[0] = '\0';
    context->canonicalized_word[0] = '\0';
    context->page = 0;
    context->offset = 0;
    context->page_id = 0;
    context->entry_count = 0;
    context->entry_index = 0;
    context->entry_length = 0;
    context->entry_arrangement = EB_ARRANGE_INVALID;
    context->in_group_entry = 0;
    context->keyword_heading.page = 0;
    context->keyword_heading.offset = 0;
  }

  LOG(("out: eb_initialize_search_context()"));
}


/*
 * Finalize search contexts of `book'.
 */
void
eb_finalize_search_contexts(EB_Book *book)
{
  LOG(("in+out: eb_finalize_search_context(book=%d)", (int)book->code));

  /* nothing to be done */
}


/*
 * Reset search context of `book'.
 */
void
eb_reset_search_contexts(EB_Book *book)
{
  LOG(("in: eb_reset_search_context(book=%d)", (int)book->code));

  eb_initialize_search_contexts(book);

  LOG(("out: eb_reset_search_context()"));
}


/*
 * Intialize a search element.
 */
void
eb_initialize_search(EB_Search *search)
{
  search->index_id = 0;
  search->start_page = 0;
  search->end_page = 0;
  search->candidates_page = 0;
  search->katakana = EB_INDEX_STYLE_CONVERT;
  search->lower = EB_INDEX_STYLE_CONVERT;
  search->mark = EB_INDEX_STYLE_DELETE;
  search->long_vowel = EB_INDEX_STYLE_CONVERT;
  search->double_consonant = EB_INDEX_STYLE_CONVERT;
  search->contracted_sound = EB_INDEX_STYLE_CONVERT;
  search->voiced_consonant = EB_INDEX_STYLE_CONVERT;
  search->small_vowel = EB_INDEX_STYLE_CONVERT;
  search->p_sound = EB_INDEX_STYLE_CONVERT;
  search->space = EB_INDEX_STYLE_DELETE;
  search->label[0] = '\0';
}


/*
 * Finalize a search element.
 */
void
eb_finalize_search(EB_Search *search)
{
  /* nothing to be done */
}


/*
 * Initialize all search elements in the current subbook.
 */
void
eb_initialize_searches(EB_Book *book)
{
  EB_Subbook *subbook;
  EB_Multi_Search *multi;
  EB_Search *entry;
  int i, j;

  LOG(("in: eb_initialize_searches(book=%d)", (int)book->code));

  subbook = book->subbook_current;

  eb_initialize_search(&subbook->word_alphabet);
  eb_initialize_search(&subbook->word_asis);
  eb_initialize_search(&subbook->word_kana);
  eb_initialize_search(&subbook->endword_alphabet);
  eb_initialize_search(&subbook->endword_asis);
  eb_initialize_search(&subbook->endword_kana);
  eb_initialize_search(&subbook->keyword);
  eb_initialize_search(&subbook->cross);
  eb_initialize_search(&subbook->menu);
  eb_initialize_search(&subbook->image_menu);
  eb_initialize_search(&subbook->copyright);
  eb_initialize_search(&subbook->text);
  eb_initialize_search(&subbook->sound);

  for (i = 0, multi = subbook->multis; i < EB_MAX_MULTI_SEARCHES;
     i++, multi++) {
    eb_initialize_search(&multi->search);
    multi->title[0] = '\0';
    multi->entry_count = 0;
    for (j = 0, entry = multi->entries;
       j < EB_MAX_MULTI_ENTRIES; j++, entry++) {
      eb_initialize_search(entry);
    }
  }

  LOG(("out: eb_initialize_searches(book=%d)", (int)book->code));
}


/*
 * Finalize all search elements in the current subbook.
 */
void
eb_finalize_searches(EB_Book *book)
{
  EB_Subbook *subbook;
  EB_Multi_Search *multi;
  EB_Search *entry;
  int i, j;

  LOG(("in: eb_finalize_searches(book=%d)", (int)book->code));

  subbook = book->subbook_current;

  eb_finalize_search(&subbook->word_alphabet);
  eb_finalize_search(&subbook->word_asis);
  eb_finalize_search(&subbook->word_kana);
  eb_finalize_search(&subbook->endword_alphabet);
  eb_finalize_search(&subbook->endword_asis);
  eb_finalize_search(&subbook->endword_kana);
  eb_finalize_search(&subbook->keyword);
  eb_finalize_search(&subbook->menu);
  eb_finalize_search(&subbook->image_menu);
  eb_finalize_search(&subbook->copyright);
  eb_finalize_search(&subbook->text);
  eb_finalize_search(&subbook->sound);

  for (i = 0, multi = subbook->multis; i < EB_MAX_KEYWORDS;
     i++, multi++) {
    eb_finalize_search(&multi->search);
    multi->entry_count = 0;
    for (j = 0, entry = multi->entries;
       j < multi->entry_count; j++, entry++) {
      eb_finalize_search(entry);
    }
  }

  LOG(("out: eb_finalize_searches()"));
}


/*
 * Pre-search for a word described in the current search context.
 * It descends intermediate indexes and reached to a leaf page that
 * may have the word.
 * If succeeded, 0 is returned.  Otherwise -1 is returned.
 */
EB_Error_Code
eb_presearch_word(EB_Book *book, EB_Search_Context *context)
{
  EB_Error_Code error_code;
  int next_page;
  int index_depth;
  char *cache_p;

  pthread_mutex_lock(&cache_mutex);
  LOG(("in: eb_presearch_word(book=%d)", (int)book->code));

  /*
   * Discard cache data.
   */
  cache_book_code = EB_BOOK_NONE;

  /*
   * Search the word in intermediate indexes.
   * Find a page number of the leaf index page.
   */
  for (index_depth = 0; index_depth < EB_MAX_INDEX_DEPTH; index_depth++) {
    next_page = context->page;

    /*
     * Seek and read a page.
     */
    if (zio_lseek(&book->subbook_current->text_zio,
      ((off_t) context->page - 1) * EB_SIZE_PAGE, SEEK_SET) < 0) {
      cache_book_code = EB_BOOK_NONE;
      error_code = EB_ERR_FAIL_SEEK_TEXT;
      goto failed;
    }
    if (zio_read(&book->subbook_current->text_zio, cache_buffer,
      EB_SIZE_PAGE) != EB_SIZE_PAGE) {
      cache_book_code = EB_BOOK_NONE;
      error_code = EB_ERR_FAIL_READ_TEXT;
      goto failed;
    }

    /*
     * Get some data from the read page.
     */
    context->page_id = eb_uint1(cache_buffer);
    context->entry_length = eb_uint1(cache_buffer + 1);
    if (context->entry_length == 0)
      context->entry_arrangement = EB_ARRANGE_VARIABLE;
    else
      context->entry_arrangement = EB_ARRANGE_FIXED;
    context->entry_count = eb_uint2(cache_buffer + 2);
    context->offset = 4;
    cache_p = cache_buffer + 4;

    LOG(("aux: eb_presearch_word(page=%d, page_id=0x%02x, \
entry_length=%d, entry_arrangement=%d, entry_count=%d)",
      context->page, context->page_id, context->entry_length,
      context->entry_arrangement, context->entry_count));

    /*
     * Exit the loop if it reached to the leaf index.
     */
    if (PAGE_ID_IS_LEAF_LAYER(context->page_id))
      break;

    /*
     * Search a page of next level index.
     */
    for (context->entry_index = 0;
       context->entry_index < context->entry_count;
       context->entry_index++) {
      if (EB_SIZE_PAGE < context->offset + context->entry_length + 4) {
        error_code = EB_ERR_UNEXP_TEXT;
        goto failed;
      }
      if (context->compare_pre(context->canonicalized_word, cache_p,
        context->entry_length) <= 0) {
        next_page = eb_uint4(cache_p + context->entry_length);
        break;
      }
      cache_p += context->entry_length + 4;
      context->offset += context->entry_length + 4;
    }
    if (context->entry_count <= context->entry_index
      || context->page == next_page) {
      context->comparison_result = -1;
      goto succeeded;
    }
    context->page = next_page;
  }

  /*
   * Check for the index depth.
   */
  if (index_depth == EB_MAX_INDEX_DEPTH) {
    error_code = EB_ERR_UNEXP_TEXT;
    goto failed;
  }

  /*
   * Update search context and cache information.
   */
  context->entry_index = 0;
  context->comparison_result = 1;
  context->in_group_entry = 0;
  cache_book_code = book->code;
  cache_page = context->page;

  succeeded:
  LOG(("out: eb_presearch_word() = %s", eb_error_string(EB_SUCCESS)));
  pthread_mutex_unlock(&cache_mutex);
  return EB_SUCCESS;

  /*
   * An error occurs...
   */
  failed:
  LOG(("out: eb_presearch_word() = %s", eb_error_string(error_code)));
  pthread_mutex_unlock(&cache_mutex);
  return error_code;
}

/*
 * Get hit entries of a submitted search request.
 */
EB_Error_Code
eb_hit_list(EB_Book *book, int max_hit_count, EB_Hit *hit_list, int *hit_count)
{
  EB_Error_Code error_code;
  EB_Search_Context temporary_context;
  EB_Hit temporary_hit_lists[EB_NUMBER_OF_SEARCH_CONTEXTS][EB_TMP_MAX_HITS];
  int temporary_hit_counts[EB_NUMBER_OF_SEARCH_CONTEXTS];
  int more_hit_count;
  int i;

  /*
   * Lock cache data and the book.
   */
  pthread_mutex_lock(&cache_mutex);
  eb_lock(&book->lock);
  LOG(("in: eb_hit_list(book=%d, max_hit_count=%d)", (int)book->code,
    max_hit_count));

  if (max_hit_count == 0)
    goto succeeded;

  *hit_count = 0;

  /*
   * Current subbook must have been set.
   */
  if (book->subbook_current == NULL) {
    error_code = EB_ERR_NO_CUR_SUB;
    goto failed;
  }

  /*
   * Get a list of hit entries.
   */
  switch (book->search_contexts->code) {
  case EB_SEARCH_EXACTWORD:
  case EB_SEARCH_WORD:
  case EB_SEARCH_ENDWORD:
    /*
     * In case of exactword, word of endword search.
     */
    error_code = eb_hit_list_word(book, book->search_contexts,
      max_hit_count, hit_list, hit_count);
    if (error_code != EB_SUCCESS)
      goto failed;
    break;

  case EB_SEARCH_KEYWORD:
  case EB_SEARCH_CROSS:
    /*
     * In case of keyword or cross search.
     */
    for (;;) {
      int search_is_over = 0;

      for (i = 0; i < EB_MAX_KEYWORDS; i++) {
        if (book->search_contexts[i].code != EB_SEARCH_KEYWORD
          && book->search_contexts[i].code != EB_SEARCH_CROSS)
          break;
        memcpy(&temporary_context, book->search_contexts + i,
          sizeof(EB_Search_Context));
        error_code = eb_hit_list_keyword(book, &temporary_context,
          EB_TMP_MAX_HITS, temporary_hit_lists[i],
          temporary_hit_counts + i);
        if (error_code != EB_SUCCESS)
          goto failed;
        if (temporary_hit_counts[i] == 0) {
          search_is_over = 1;
          break;
        }
      }
      if (search_is_over)
        break;

      eb_and_hit_lists(hit_list + *hit_count, &more_hit_count,
        max_hit_count - *hit_count, i, temporary_hit_lists,
        temporary_hit_counts);

      for (i = 0; i < EB_MAX_MULTI_ENTRIES; i++) {
        if (book->search_contexts[i].code != EB_SEARCH_KEYWORD
          && book->search_contexts[i].code != EB_SEARCH_CROSS)
          break;
        error_code = eb_hit_list_keyword(book,
          book->search_contexts + i, temporary_hit_counts[i],
          temporary_hit_lists[i], temporary_hit_counts + i);
        if (error_code != EB_SUCCESS)
          goto failed;
      }

      *hit_count += more_hit_count;
      if (max_hit_count <= *hit_count)
        break;
    }
    break;

  case EB_SEARCH_MULTI:
    /*
     * In case of multi search.
     */
    for (;;) {
      int search_is_over = 0;

      for (i = 0; i < EB_MAX_MULTI_ENTRIES; i++) {
        if (book->search_contexts[i].code != EB_SEARCH_MULTI)
          break;
        memcpy(&temporary_context, book->search_contexts + i,
          sizeof(EB_Search_Context));
        error_code = eb_hit_list_multi(book, &temporary_context,
          EB_TMP_MAX_HITS, temporary_hit_lists[i],
          temporary_hit_counts + i);
        if (error_code != EB_SUCCESS)
          goto failed;
        if (temporary_hit_counts[i] == 0) {
          search_is_over = 1;
          break;
        }
      }
      if (search_is_over)
        break;

      eb_and_hit_lists(hit_list + *hit_count, &more_hit_count,
        max_hit_count - *hit_count, i, temporary_hit_lists,
        temporary_hit_counts);

      for (i = 0; i < EB_MAX_MULTI_ENTRIES; i++) {
        if (book->search_contexts[i].code != EB_SEARCH_MULTI)
          break;
        error_code = eb_hit_list_multi(book,
          book->search_contexts + i, temporary_hit_counts[i],
          temporary_hit_lists[i], temporary_hit_counts + i);
        if (error_code != EB_SUCCESS)
          goto failed;
      }

      *hit_count += more_hit_count;
      if (max_hit_count <= *hit_count)
        break;
    }
    break;

  default:
    /* not reached */
    error_code = EB_ERR_NO_PREV_SEARCH;
    goto failed;
  }

  /*
   * Unlock cache data and the book.
   */
  succeeded:
  LOG(("out: eb_hit_list(hit_count=%d) = %s",
    *hit_count, eb_error_string(EB_SUCCESS)));
  eb_unlock(&book->lock);
  pthread_mutex_unlock(&cache_mutex);
  return EB_SUCCESS;

  /*
   * An error occurs...
   */
  failed:
  *hit_count = 0;
  LOG(("out: eb_hit_list() = %s", eb_error_string(error_code)));
  eb_unlock(&book->lock);
  pthread_mutex_unlock(&cache_mutex);
  return error_code;
}


/*
 * Get hit entries of a submitted exactword/word/endword search request.
 */
static EB_Error_Code
eb_hit_list_word(EB_Book *book, EB_Search_Context *context, int max_hit_count,
  EB_Hit *hit_list, int *hit_count)
{
  EB_Error_Code error_code;
  EB_Hit *hit;
  int group_id;
  char *cache_p;

  LOG(("in: eb_hit_list_word(book=%d, max_hit_count=%d)", (int)book->code,
    max_hit_count));

  hit = hit_list;
  *hit_count = 0;

  /*
   * If the result of previous comparison is negative value, all
   * matched entries have been found.
   */
  if (context->comparison_result < 0 || max_hit_count <= 0)
    goto succeeded;

  for (;;) {
    /*
     * Read a page to search, if the page is not on the cache buffer.
     *
     * Cache may be missed by the two reasons:
     *   1. the search process reaches to the end of an index page,
     *    and tries to read the next page.
     *   2. Someone else used the cache buffer.
     *
     * At the case of 1, the search process reads the page and update
     * the search context.  At the case of 2. it reads the page but
     * must not update the context!
     */
    if (cache_book_code != book->code || cache_page != context->page) {
      if (zio_lseek(&book->subbook_current->text_zio,
        ((off_t) context->page - 1) * EB_SIZE_PAGE, SEEK_SET) < 0) {
        error_code = EB_ERR_FAIL_SEEK_TEXT;
        goto failed;
      }
      if (zio_read(&book->subbook_current->text_zio,
        cache_buffer, EB_SIZE_PAGE) != EB_SIZE_PAGE) {
        error_code = EB_ERR_FAIL_READ_TEXT;
        goto failed;
      }

      /*
       * Update search context.
       */
      if (context->entry_index == 0) {
        context->page_id = eb_uint1(cache_buffer);
        context->entry_length = eb_uint1(cache_buffer + 1);
        if (context->entry_length == 0)
          context->entry_arrangement = EB_ARRANGE_VARIABLE;
        else
          context->entry_arrangement = EB_ARRANGE_FIXED;
        context->entry_count = eb_uint2(cache_buffer + 2);
        context->entry_index = 0;
        context->offset = 4;
      }

      cache_book_code = book->code;
      cache_page = context->page;
    }

    cache_p = cache_buffer + context->offset;

    LOG(("aux: eb_hit_list_word(page=%d, page_id=0x%02x, \
entry_length=%d, entry_arrangement=%d, entry_count=%d)",
      context->page, context->page_id, context->entry_length,
      context->entry_arrangement, context->entry_count));

    if (!PAGE_ID_IS_LEAF_LAYER(context->page_id)) {
      /*
       * Not a leaf index.  It is an error.
       */
      error_code = EB_ERR_UNEXP_TEXT;
      goto failed;
    }

    if (!PAGE_ID_HAVE_GROUP_ENTRY(context->page_id)
      && context->entry_arrangement == EB_ARRANGE_FIXED) {
      /*
       * The leaf index doesn't have a group entry.
       * Find text and heading locations.
       */
      while (context->entry_index < context->entry_count) {
        if (EB_SIZE_PAGE
          < context->offset + context->entry_length + 12) {
          error_code = EB_ERR_UNEXP_TEXT;
          goto failed;
        }

        /*
         * Compare word and pattern.
         * If matched, add it to a hit list.
         */
        context->comparison_result
          = context->compare_single(context->word, cache_p,
            context->entry_length);
        if (context->comparison_result == 0) {
          hit->heading.page
            = eb_uint4(cache_p + context->entry_length + 6);
          hit->heading.offset
            = eb_uint2(cache_p + context->entry_length + 10);
          hit->text.page
            = eb_uint4(cache_p + context->entry_length);
          hit->text.offset
            = eb_uint2(cache_p + context->entry_length + 4);
          hit++;
          *hit_count += 1;
        }
        context->entry_index++;
        context->offset += context->entry_length + 12;
        cache_p += context->entry_length + 12;

        if (context->comparison_result < 0
          || max_hit_count <= *hit_count)
          goto succeeded;
      }

    } else if (!PAGE_ID_HAVE_GROUP_ENTRY(context->page_id)
      && context->entry_arrangement == EB_ARRANGE_VARIABLE) {

      /*
       * The leaf index doesn't have a group entry.
       * Find text and heading locations.
       */
      while (context->entry_index < context->entry_count) {
        if (EB_SIZE_PAGE < context->offset + 1) {
          error_code = EB_ERR_UNEXP_TEXT;
          goto failed;
        }
        context->entry_length = eb_uint1(cache_p);
        if (EB_SIZE_PAGE
          < context->offset + context->entry_length + 13) {
          error_code = EB_ERR_UNEXP_TEXT;
          goto failed;
        }

        /*
         * Compare word and pattern.
         * If matched, add it to a hit list.
         */
        context->comparison_result
          = context->compare_single(context->word, cache_p + 1,
            context->entry_length);
        if (context->comparison_result == 0) {
          hit->heading.page
            = eb_uint4(cache_p + context->entry_length + 7);
          hit->heading.offset
            = eb_uint2(cache_p + context->entry_length + 11);
          hit->text.page
            = eb_uint4(cache_p + context->entry_length + 1);
          hit->text.offset
            = eb_uint2(cache_p + context->entry_length + 5);
          hit++;
          *hit_count += 1;
        }
        context->entry_index++;
        context->offset += context->entry_length + 13;
        cache_p += context->entry_length + 13;

        if (context->comparison_result < 0
          || max_hit_count <= *hit_count)
          goto succeeded;
      }

    } else {
      /*
       * The leaf index have a group entry.
       * Find text and heading locations.
       */
      while (context->entry_index < context->entry_count) {
        if (EB_SIZE_PAGE < context->offset + 2) {
          error_code = EB_ERR_UNEXP_TEXT;
          goto failed;
        }
        group_id = eb_uint1(cache_p);

        if (group_id == 0x00) {
          /*
           * 0x00 -- Single entry.
           */
          context->entry_length = eb_uint1(cache_p + 1);
          if (EB_SIZE_PAGE
            < context->offset + context->entry_length + 14) {
            error_code = EB_ERR_UNEXP_TEXT;
            goto failed;
          }

          /*
           * Compare word and pattern.
           * If matched, add it to a hit list.
           */
          context->comparison_result
            = context->compare_single(context->canonicalized_word,
              cache_p + 2, context->entry_length);
          if (context->comparison_result == 0) {
            hit->heading.page
              = eb_uint4(cache_p + context->entry_length + 8);
            hit->heading.offset
              = eb_uint2(cache_p + context->entry_length + 12);
            hit->text.page
              = eb_uint4(cache_p + context->entry_length + 2);
            hit->text.offset
              = eb_uint2(cache_p + context->entry_length + 6);
            hit++;
            *hit_count += 1;
          }
          context->in_group_entry = 0;
          context->offset += context->entry_length + 14;
          cache_p += context->entry_length + 14;

        } else if (group_id == 0x80) {
          /*
           * 0x80 -- Start of group entry.
           */
          context->entry_length = eb_uint1(cache_p + 1);
          if (EB_SIZE_PAGE
            < context->offset + context->entry_length + 4) {
            error_code = EB_ERR_UNEXP_TEXT;
            goto failed;
          }
          context->comparison_result
            = context->compare_single(context->canonicalized_word,
              cache_p + 4, context->entry_length);
          context->in_group_entry = 1;
          cache_p += context->entry_length + 4;
          context->offset += context->entry_length + 4;

        } else if (group_id == 0xc0) {
          /*
           * Element of the group entry
           */
          context->entry_length = eb_uint1(cache_p + 1);
          if (EB_SIZE_PAGE < context->offset + 14) {
            error_code = EB_ERR_UNEXP_TEXT;
            goto failed;
          }

          /*
           * Compare word and pattern.
           * If matched, add it to a hit list.
           */
          if (context->comparison_result == 0
            && context->in_group_entry
            && context->compare_group(context->word, cache_p + 2,
              context->entry_length) == 0) {
            hit->heading.page
              = eb_uint4(cache_p + context->entry_length + 8);
            hit->heading.offset
              = eb_uint2(cache_p + context->entry_length + 12);
            hit->text.page
              = eb_uint4(cache_p + context->entry_length + 2);
            hit->text.offset
              = eb_uint2(cache_p + context->entry_length + 6);
            hit++;
            *hit_count += 1;
          }
          context->offset += context->entry_length + 14;
          cache_p += context->entry_length + 14;

        } else {
          /*
           * Unknown group ID.
           */
          error_code = EB_ERR_UNEXP_TEXT;
          goto failed;
        }

        context->entry_index++;
        if (context->comparison_result < 0
          || max_hit_count <= *hit_count)
          goto succeeded;
      }
    }

    /*
     * Go to a next page if available.
     */
    if (PAGE_ID_IS_LAYER_END(context->page_id)) {
      context->comparison_result = -1;
      goto succeeded;
    }
    context->page++;
    context->entry_index = 0;
  }

  succeeded:
  LOG(("out: eb_hit_list_word(hit_count=%d) = %s",
    *hit_count, eb_error_string(EB_SUCCESS)));
  return EB_SUCCESS;

  /*
   * An error occurs...
   * Discard cache if read error occurs.
   */
  failed:
  if (error_code == EB_ERR_FAIL_READ_TEXT)
    cache_book_code = EB_BOOK_NONE;
  *hit_count = 0;
  LOG(("out: eb_hit_list_word() = %s", eb_error_string(error_code)));
  return error_code;
}


/*
 * Get hit entries of a submitted keyword search request.
 */
static EB_Error_Code
eb_hit_list_keyword(EB_Book *book, EB_Search_Context *context,
  int max_hit_count, EB_Hit *hit_list, int *hit_count)
{
  EB_Error_Code error_code;
  EB_Text_Context text_context;
  EB_Hit *hit;
  int group_id;
  char *cache_p;

  LOG(("in: eb_hit_list_keyword(book=%d, max_hit_count=%d)",
    (int)book->code, max_hit_count));

  hit = hit_list;
  *hit_count = 0;

  /*
   * Backup the text context in `book'.
   */
  memcpy(&text_context, &book->text_context, sizeof(EB_Text_Context));

  /*
   * Seek text file.
   */
  if (context->in_group_entry && context->comparison_result == 0) {
    error_code = eb_seek_text(book, &context->keyword_heading);
    if (error_code != EB_SUCCESS)
      goto failed;
  }

  /*
   * If the result of previous comparison is negative value, all
   * matched entries have been found.
   */
  if (context->comparison_result < 0 || max_hit_count <= 0)
    goto succeeded;

  for (;;) {
    /*
     * Read a page to search, if the page is not on the cache buffer.
     *
     * Cache may be missed by the two reasons:
     *   1. the search process reaches to the end of an index page,
     *    and tries to read the next page.
     *   2. Someone else used the cache buffer.
     *
     * At the case of 1, the search process reads the page and update
     * the search context.  At the case of 2. it reads the page but
     * must not update the context!
     */
    if (cache_book_code != book->code || cache_page != context->page) {
      if (zio_lseek(&book->subbook_current->text_zio,
        ((off_t) context->page - 1) * EB_SIZE_PAGE, SEEK_SET) < 0) {
        error_code = EB_ERR_FAIL_SEEK_TEXT;
        goto failed;
      }
      if (zio_read(&book->subbook_current->text_zio, cache_buffer,
        EB_SIZE_PAGE) != EB_SIZE_PAGE) {
        error_code = EB_ERR_FAIL_READ_TEXT;
        goto failed;
      }

      /*
       * Update search context.
       */
      if (context->entry_index == 0) {
        context->page_id = eb_uint1(cache_buffer);
        context->entry_length = eb_uint1(cache_buffer + 1);
        if (context->entry_length == 0)
          context->entry_arrangement = EB_ARRANGE_VARIABLE;
        else
          context->entry_arrangement = EB_ARRANGE_FIXED;
        context->entry_count = eb_uint2(cache_buffer + 2);
        context->entry_index = 0;
        context->offset = 4;
      }

      cache_book_code = book->code;
      cache_page = context->page;
    }

    cache_p = cache_buffer + context->offset;

    LOG(("aux: eb_hit_list_keyword(page=%d, page_id=0x%02x, \
entry_length=%d, entry_arrangement=%d, entry_count=%d)",
      context->page, context->page_id, context->entry_length,
      context->entry_arrangement, context->entry_count));

    if (!PAGE_ID_IS_LEAF_LAYER(context->page_id)) {
      /*
       * Not a leaf index.  It is an error.
       */
      error_code = EB_ERR_UNEXP_TEXT;
      goto failed;
    }

    if (!PAGE_ID_HAVE_GROUP_ENTRY(context->page_id)
      && context->entry_arrangement == EB_ARRANGE_FIXED) {
      /*
       * The leaf index doesn't have a group entry.
       * Find text and heading locations.
       */
      while (context->entry_index < context->entry_count) {
        if (EB_SIZE_PAGE
          < context->offset + context->entry_length + 12) {
          error_code = EB_ERR_UNEXP_TEXT;
          goto failed;
        }

        /*
         * Compare word and pattern.
         * If matched, add it to a hit list.
         */
        context->comparison_result
          = context->compare_single(context->word, cache_p,
            context->entry_length);
        if (context->comparison_result == 0) {
          hit->heading.page
            = eb_uint4(cache_p + context->entry_length + 6);
          hit->heading.offset
            = eb_uint2(cache_p + context->entry_length + 10);
          hit->text.page
            = eb_uint4(cache_p + context->entry_length);
          hit->text.offset
            = eb_uint2(cache_p + context->entry_length + 4);
          hit++;
          *hit_count += 1;
        }
        context->entry_index++;
        context->offset += context->entry_length + 12;
        cache_p += context->entry_length + 12;

        if (context->comparison_result < 0
          || max_hit_count <= *hit_count)
          goto succeeded;
      }

    } else if (!PAGE_ID_HAVE_GROUP_ENTRY(context->page_id)
      && context->entry_arrangement == EB_ARRANGE_VARIABLE) {
      /*
       * The leaf index doesn't have a group entry.
       * Find text and heading locations.
       */
      while (context->entry_index < context->entry_count) {
        if (EB_SIZE_PAGE < context->offset + 1) {
          error_code = EB_ERR_UNEXP_TEXT;
          goto failed;
        }
        context->entry_length = eb_uint1(cache_p);
        if (EB_SIZE_PAGE
          < context->offset + context->entry_length + 13) {
          error_code = EB_ERR_UNEXP_TEXT;
          goto failed;
        }

        /*
         * Compare word and pattern.
         * If matched, add it to a hit list.
         */
        context->comparison_result
          = context->compare_single(context->word, cache_p + 1,
            context->entry_length);
        if (context->comparison_result == 0) {
          hit->heading.page
            = eb_uint4(cache_p + context->entry_length + 7);
          hit->heading.offset
            = eb_uint2(cache_p + context->entry_length + 11);
          hit->text.page
            = eb_uint4(cache_p + context->entry_length + 1);
          hit->text.offset
            = eb_uint2(cache_p + context->entry_length + 5);
          hit++;
          *hit_count += 1;
        }
        context->entry_index++;
        context->offset += context->entry_length + 13;
        cache_p += context->entry_length + 13;

        if (context->comparison_result < 0
          || max_hit_count <= *hit_count)
          goto succeeded;
      }

    } else {
      /*
       * The leaf index have a group entry.
       * Find text and heading locations.
       */
      while (context->entry_index < context->entry_count) {
        if (EB_SIZE_PAGE < context->offset + 2) {
          error_code = EB_ERR_UNEXP_TEXT;
          goto failed;
        }
        group_id = eb_uint1(cache_p);

        if (group_id == 0x00) {
          /*
           * 0x00 -- Single entry.
           */
          context->entry_length = eb_uint1(cache_p + 1);
          if (EB_SIZE_PAGE
            < context->offset + context->entry_length + 14) {
            error_code = EB_ERR_UNEXP_TEXT;
            goto failed;
          }

          /*
           * Compare word and pattern.
           * If matched, add it to a hit list.
           */
          context->comparison_result
            = context->compare_single(context->canonicalized_word,
              cache_p + 2, context->entry_length);
          if (context->comparison_result == 0) {
            hit->heading.page
              = eb_uint4(cache_p + context->entry_length + 8);
            hit->heading.offset
              = eb_uint2(cache_p + context->entry_length + 12);
            hit->text.page
              = eb_uint4(cache_p + context->entry_length + 2);
            hit->text.offset
              = eb_uint2(cache_p + context->entry_length + 6);
            hit++;
            *hit_count += 1;
          }
          context->in_group_entry = 0;
          context->offset += context->entry_length + 14;
          cache_p += context->entry_length + 14;

        } else if (group_id == 0x80) {
          /*
           * 0x80 -- Start of group entry.
           */
          context->entry_length = eb_uint1(cache_p + 1);
          if (EB_SIZE_PAGE
            < context->offset + context->entry_length + 12) {
            error_code = EB_ERR_UNEXP_TEXT;
            goto failed;
          }
          context->comparison_result
            = context->compare_single(context->word, cache_p + 6,
              context->entry_length);
          context->keyword_heading.page
            = eb_uint4(cache_p + context->entry_length + 6);
          context->keyword_heading.offset
            = eb_uint2(cache_p + context->entry_length + 10);
          context->in_group_entry = 1;
          cache_p += context->entry_length + 12;
          context->offset += context->entry_length + 12;

          if (context->comparison_result == 0) {
            error_code
              = eb_seek_text(book, &context->keyword_heading);
            if (error_code != EB_SUCCESS)
              goto failed;
          }

        } else if (group_id == 0xc0) {
          /*
           * Element of the group entry.
           */
          if (EB_SIZE_PAGE < context->offset + 7) {
            error_code = EB_ERR_UNEXP_TEXT;
            goto failed;
          }

          /*
           * Compare word and pattern.
           * If matched, add it to a hit list.
           */
          if (context->in_group_entry
            && context->comparison_result == 0) {
            error_code
              = eb_tell_text(book, &context->keyword_heading);
            if (error_code != EB_SUCCESS)
              goto failed;
            hit->heading.page   = context->keyword_heading.page;
            hit->heading.offset = context->keyword_heading.offset;
            hit->text.page    = eb_uint4(cache_p + 1);
            hit->text.offset  = eb_uint2(cache_p + 5);
            hit++;
            *hit_count += 1;
            error_code = eb_forward_heading(book);
            if (error_code != EB_SUCCESS)
              goto failed;
          }
          context->offset += 7;
          cache_p += 7;

        } else {
          /*
           * Unknown group ID.
           */
          error_code = EB_ERR_UNEXP_TEXT;
          goto failed;
        }

        context->entry_index++;
        if (context->comparison_result < 0
          || max_hit_count <= *hit_count)
          goto succeeded;
      }
    }

    /*
     * Go to a next page if available.
     */
    if (PAGE_ID_IS_LAYER_END(context->page_id)) {
      context->comparison_result = -1;
      goto succeeded;
    }
    context->page++;
    context->entry_index = 0;
  }

  succeeded:
  if (context->in_group_entry && context->comparison_result == 0) {
    error_code = eb_tell_text(book, &context->keyword_heading);
    if (error_code != EB_SUCCESS)
      goto failed;
  }

  /*
   * Restore the text context in `book'.
   */
  memcpy(&book->text_context, &text_context, sizeof(EB_Text_Context));
  LOG(("out: eb_hit_list_keyword(hit_count=%d) = %s",
    *hit_count, eb_error_string(EB_SUCCESS)));
  return EB_SUCCESS;

  /*
   * An error occurs...
   * Discard cache if read error occurs.
   */
  failed:
  if (error_code == EB_ERR_FAIL_READ_TEXT)
    cache_book_code = EB_BOOK_NONE;
  *hit_count = 0;
  memcpy(&book->text_context, &text_context, sizeof(EB_Text_Context));
  LOG(("out: eb_hit_list_keyword() = %s", eb_error_string(error_code)));
  return error_code;
}


/*
 * Get hit entries of a submitted multi search request.
 */
static EB_Error_Code
eb_hit_list_multi(EB_Book *book, EB_Search_Context *context, int max_hit_count,
  EB_Hit *hit_list, int *hit_count)
{
  EB_Error_Code error_code;
  EB_Hit *hit;
  int group_id;
  char *cache_p;

  LOG(("in: eb_hit_list_multi(book=%d, max_hit_count=%d)", (int)book->code,
    max_hit_count));

  hit = hit_list;
  *hit_count = 0;

  /*
   * If the result of previous comparison is negative value, all
   * matched entries have been found.
   */
  if (context->comparison_result < 0 || max_hit_count <= 0)
    goto succeeded;

  for (;;) {
    /*
     * Read a page to search, if the page is not on the cache buffer.
     *
     * Cache may be missed by the two reasons:
     *   1. the search process reaches to the end of an index page,
     *    and tries to read the next page.
     *   2. Someone else used the cache buffer.
     *
     * At the case of 1, the search process reads the page and update
     * the search context.  At the case of 2. it reads the page but
     * must not update the context!
     */
    if (cache_book_code != book->code || cache_page != context->page) {
      if (zio_lseek(&book->subbook_current->text_zio,
        ((off_t) context->page - 1) * EB_SIZE_PAGE, SEEK_SET) < 0) {
        error_code = EB_ERR_FAIL_SEEK_TEXT;
        goto failed;
      }
      if (zio_read(&book->subbook_current->text_zio, cache_buffer,
        EB_SIZE_PAGE) != EB_SIZE_PAGE) {
        error_code = EB_ERR_FAIL_READ_TEXT;
        goto failed;
      }

      /*
       * Update search context.
       */
      if (context->entry_index == 0) {
        context->page_id = eb_uint1(cache_buffer);
        context->entry_length = eb_uint1(cache_buffer + 1);
        if (context->entry_length == 0)
          context->entry_arrangement = EB_ARRANGE_VARIABLE;
        else
          context->entry_arrangement = EB_ARRANGE_FIXED;
        context->entry_count = eb_uint2(cache_buffer + 2);
        context->entry_index = 0;
        context->offset = 4;
      }

      cache_book_code = book->code;
      cache_page = context->page;
    }

    cache_p = cache_buffer + context->offset;

    LOG(("aux: eb_hit_list_multi(page=%d, page_id=0x%02x, \
entry_length=%d, entry_arrangement=%d, entry_count=%d)",
      context->page, context->page_id, context->entry_length,
      context->entry_arrangement, context->entry_count));

    if (!PAGE_ID_IS_LEAF_LAYER(context->page_id)) {
      /*
       * Not a leaf index.  It is an error.
       */
      error_code = EB_ERR_UNEXP_TEXT;
      goto failed;
    }

    if (!PAGE_ID_HAVE_GROUP_ENTRY(context->page_id)
      && context->entry_arrangement == EB_ARRANGE_FIXED) {
      /*
       * The leaf index doesn't have a group entry.
       * Find text and heading locations.
       */
      while (context->entry_index < context->entry_count) {
        if (EB_SIZE_PAGE
          < context->offset + context->entry_length + 13) {
          error_code = EB_ERR_UNEXP_TEXT;
          goto failed;
        }

        /*
         * Compare word and pattern.
         * If matched, add it to a hit list.
         */
        context->comparison_result
          = context->compare_single(context->word, cache_p,
            context->entry_length);
        if (context->comparison_result == 0) {
          hit->heading.page
            = eb_uint4(cache_p + context->entry_length + 6);
          hit->heading.offset
            = eb_uint2(cache_p + context->entry_length + 10);
          hit->text.page
            = eb_uint4(cache_p + context->entry_length);
          hit->text.offset
            = eb_uint2(cache_p + context->entry_length + 4);
          hit++;
          *hit_count += 1;
        }
        context->entry_index++;
        context->offset += context->entry_length + 12;
        cache_p += context->entry_length + 12;

        if (context->comparison_result < 0
          || max_hit_count <= *hit_count)
          goto succeeded;
      }

    } else if (!PAGE_ID_HAVE_GROUP_ENTRY(context->page_id)
      && context->entry_arrangement == EB_ARRANGE_VARIABLE) {
      /*
       * The leaf index doesn't have a group entry.
       * Find text and heading locations.
       */
      while (context->entry_index < context->entry_count) {
        if (EB_SIZE_PAGE < context->offset + 1) {
          error_code = EB_ERR_UNEXP_TEXT;
          goto failed;
        }
        context->entry_length = eb_uint1(cache_p);
        if (EB_SIZE_PAGE
          < context->offset + context->entry_length + 13) {
          error_code = EB_ERR_UNEXP_TEXT;
          goto failed;
        }

        /*
         * Compare word and pattern.
         * If matched, add it to a hit list.
         */
        context->comparison_result
          = context->compare_single(context->word, cache_p + 1,
            context->entry_length);
        if (context->comparison_result == 0) {
          hit->heading.page
            = eb_uint4(cache_p + context->entry_length + 7);
          hit->heading.offset
            = eb_uint2(cache_p + context->entry_length + 11);
          hit->text.page
            = eb_uint4(cache_p + context->entry_length + 1);
          hit->text.offset
            = eb_uint2(cache_p + context->entry_length + 5);
          hit++;
          *hit_count += 1;
        }
        context->entry_index++;
        context->offset += context->entry_length + 13;
        cache_p += context->entry_length + 13;

        if (context->comparison_result < 0
          || max_hit_count <= *hit_count)
          goto succeeded;
      }

    } else {
      /*
       * The leaf index have a group entry.
       * Find text and heading locations.
       */
      while (context->entry_index < context->entry_count) {
        if (EB_SIZE_PAGE < context->offset + 2) {
          error_code = EB_ERR_UNEXP_TEXT;
          goto failed;
        }
        group_id = eb_uint1(cache_p);

        if (group_id == 0x00) {
          /*
           * 0x00 -- Single entry.
           */
          context->entry_length = eb_uint1(cache_p + 1);
          if (EB_SIZE_PAGE
            < context->offset + context->entry_length + 14) {
            error_code = EB_ERR_UNEXP_TEXT;
            goto failed;
          }

          /*
           * Compare word and pattern.
           * If matched, add it to a hit list.
           */
          context->comparison_result
            = context->compare_single(context->canonicalized_word,
              cache_p + 2, context->entry_length);
          if (context->comparison_result == 0) {
            hit->heading.page
              = eb_uint4(cache_p + context->entry_length + 8);
            hit->heading.offset
              = eb_uint2(cache_p + context->entry_length + 12);
            hit->text.page
              = eb_uint4(cache_p + context->entry_length + 2);
            hit->text.offset
              = eb_uint2(cache_p + context->entry_length + 6);
            hit++;
            *hit_count += 1;
          }
          context->in_group_entry = 0;
          context->offset += context->entry_length + 14;
          cache_p += context->entry_length + 14;

        } else if (group_id == 0x80) {
          /*
           * 0x80 -- Start of group entry.
           */
          context->entry_length = eb_uint1(cache_p + 1);
          if (EB_SIZE_PAGE
            < context->offset + context->entry_length + 6) {
            error_code = EB_ERR_UNEXP_TEXT;
            goto failed;
          }
          context->comparison_result
            = context->compare_single(context->word, cache_p + 6,
              context->entry_length);
          context->in_group_entry = 1;
          cache_p += context->entry_length + 6;
          context->offset += context->entry_length + 6;

        } else if (group_id == 0xc0) {
          /*
           * Element of the group entry.
           */
          if (EB_SIZE_PAGE < context->offset + 13) {
            error_code = EB_ERR_UNEXP_TEXT;
            goto failed;
          }

          /*
           * Compare word and pattern.
           * If matched, add it to a hit list.
           */
          if (context->in_group_entry
            && context->comparison_result == 0) {
            hit->heading.page   = eb_uint4(cache_p + 7);
            hit->heading.offset = eb_uint2(cache_p + 11);
            hit->text.page    = eb_uint4(cache_p + 1);
            hit->text.offset  = eb_uint2(cache_p + 5);
            hit++;
            *hit_count += 1;
          }
          context->offset += 13;
          cache_p += 13;

        } else {
          /*
           * Unknown group ID.
           */
          error_code = EB_ERR_UNEXP_TEXT;
          goto failed;
        }

        context->entry_index++;
        if (context->comparison_result < 0
          || max_hit_count <= *hit_count)
          goto succeeded;
      }
    }

    /*
     * Go to a next page if available.
     */
    if (PAGE_ID_IS_LAYER_END(context->page_id)) {
      context->comparison_result = -1;
      goto succeeded;
    }
    context->page++;
    context->entry_index = 0;
  }

  succeeded:
  LOG(("out: eb_hit_list_multi(hit_count=%d) = %s",
    *hit_count, eb_error_string(EB_SUCCESS)));
  return EB_SUCCESS;

  /*
   * An error occurs...
   * Discard cache if read error occurs.
   */
  failed:
  if (error_code == EB_ERR_FAIL_READ_TEXT)
    cache_book_code = EB_BOOK_NONE;
  *hit_count = 0;
  LOG(("out: eb_hit_list_multi() = %s", eb_error_string(error_code)));
  return error_code;
}


/*
 * Do AND operation of hit lists.
 * and_list = hit_lists[0] AND hit_lists[1] AND ...
 */
static void
eb_and_hit_lists(EB_Hit and_list[EB_TMP_MAX_HITS], int *and_count,
  int max_and_count, int hit_list_count,
  EB_Hit hit_lists[EB_NUMBER_OF_SEARCH_CONTEXTS][EB_TMP_MAX_HITS],
  int hit_counts[EB_NUMBER_OF_SEARCH_CONTEXTS])
{
  int hit_indexes[EB_NUMBER_OF_SEARCH_CONTEXTS];
  int greatest_list;
  int greatest_page;
  int greatest_offset;
  int current_page;
  int current_offset;
  int equal_count;
  int increment_count;
  int i;

  LOG(("in: eb_and_hit_lists(max_and_count=%d, hit_list_count=%d)",
    max_and_count, hit_list_count));

  /*
   * Initialize indexes for the hit_lists[].
   */
  for (i = 0; i < hit_list_count; i++)
    hit_indexes[i] = 0;

  /*
   * Generate the new list `and_list'.
   */
  *and_count = 0;
  while (*and_count < max_and_count) {
    /*
     * Initialize variables.
     */
    greatest_list = -1;
    greatest_page = 0;
    greatest_offset = 0;
    current_page = 0;
    current_offset = 0;
    equal_count = 0;

    /*
     * Compare the current elements of the lists.
     */
    for (i = 0; i < hit_list_count; i++) {
      /*
       * If we have been reached to the tail of the hit_lists[i],
       * skip the list.
       */
      if (hit_counts[i] <= hit_indexes[i])
        continue;

      /*
       * Compare {current_page, current_offset} and {greatest_page,
       * greatest_offset}.
       */
      current_page = hit_lists[i][hit_indexes[i]].text.page;
      current_offset = hit_lists[i][hit_indexes[i]].text.offset;

      if (greatest_list == -1) {
        greatest_page = current_page;
        greatest_offset = current_offset;
        greatest_list = i;
        equal_count++;
      } else if (greatest_page < current_page) {
        greatest_page = current_page;
        greatest_offset = current_offset;
        greatest_list = i;
      } else if (current_page == greatest_page
        && greatest_offset < current_offset) {
        greatest_page = current_page;
        greatest_offset = current_offset;
        greatest_list = i;
      } else if (current_page == greatest_page
        && current_offset == greatest_offset) {
        equal_count++;
      }
    }

    if (equal_count == hit_list_count) {
      /*
       * All the current elements of the lists point to the same
       * position.  This is hit element.  Increase indexes of all
       * lists.
       */
      memcpy(and_list + *and_count, hit_lists[0] + hit_indexes[0],
        sizeof(EB_Hit));
      *and_count += 1;
      for (i = 0; i < hit_list_count; i++) {
        if (hit_counts[i] <= hit_indexes[i])
          continue;
        hit_indexes[i]++;
      }
    } else {
      /*
       * This is not hit element.  Increase indexes of all lists
       * except for greatest element(s).  If there is no list
       * whose index is incremented, our job has been completed.
       */
      increment_count = 0;
      for (i = 0; i < hit_list_count; i++) {
        if (hit_counts[i] <= hit_indexes[i])
          continue;
        current_page = hit_lists[i][hit_indexes[i]].text.page;
        current_offset = hit_lists[i][hit_indexes[i]].text.offset;
        if (current_page != greatest_page
          || current_offset != greatest_offset) {
          hit_indexes[i]++;
          increment_count++;
        }
      }
      if (increment_count == 0)
        break;
    }
  }

  /*
   * Update hit_counts[].
   * The hit counts of the lists are set to the current indexes.
   */
  for (i = 0; i < hit_list_count; i++)
    hit_counts[i] = hit_indexes[i];

  LOG(("out: eb_and_hit_lists(and_count=%d)", *and_count));
}
