dict/lookup.c

   1 /*
   2  * Copyright (C) 1994, Index Data I/S
   3  * All rights reserved.
   4  * Sebastian Hammer, Adam Dickmeiss
   5  *
   6  * $Log: lookup.c,v $
   7  * Revision 1.4  1994-10-05 12:16:51  adam
   8  * Pagesize is a resource now.
   9  *
  10  * Revision 1.3  1994/09/26  10:17:25  adam
  11  * Minor changes.
  12  *
  13  * Revision 1.2  1994/09/16  15:39:14  adam
  14  * Initial code of lookup - not tested yet.
  15  *
  16  * Revision 1.1  1994/08/16  16:26:48  adam
  17  * Added dict.
  18  *
  19  */
  20
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <stdio.h>
  24 #include <assert.h>
  25
  26 #include <dict.h>
  27
  28 static char *dict_look (Dict dict, Dict_char *str)
  29 {
  30     Dict_ptr ptr = 1;
  31     int mid, lo, hi;
  32     int cmp;
  33     void *p;
  34     short *indxp;
  35     char *info;
  36
  37     dict_bf_readp (dict->dbf, ptr, &p);
  38     mid = lo = 0;
  39     hi = DICT_nodir(p)-1;
  40     indxp = (short*) ((char*) p+DICT_pagesize(dict)-sizeof(short));
  41     while (lo <= hi)
  42     {
  43         mid = (lo+hi)/2;
  44         if (indxp[-mid] > 0)
  45         {
  46             /* string (Dict_char *) DICT_EOS terminated */
  47             /* unsigned char        length of information */
  48             /* char *               information */
  49             info = (char*)p + indxp[-mid];
  50             cmp = dict_strcmp((Dict_char*) info, str);
  51             if (!cmp)
  52                 return info+(dict_strlen (info)+1)*sizeof(Dict_char);
  53         }
  54         else
  55         {
  56             Dict_char dc;
  57             Dict_ptr subptr;
  58
  59             /* Dict_ptr             subptr */
  60             /* Dict_char            sub char */
  61             /* unsigned char        length of information */
  62             /* char *               information */
  63             info = (char*)p - indxp[-mid];
  64             memcpy (&dc, info+sizeof(Dict_ptr), sizeof(Dict_char));
  65             cmp = dc- *str;
  66             if (!cmp)
  67             {
  68                 memcpy (&subptr, info, sizeof(Dict_ptr));
  69                 if (*++str == DICT_EOS)
  70                 {
  71                     if (info[sizeof(Dict_ptr)+sizeof(Dict_char)])
  72                         return info+sizeof(Dict_ptr)+sizeof(Dict_char);
  73                     return NULL;
  74                 }
  75                 else
  76                 {
  77                     if (subptr == 0)
  78                         return NULL;
  79                     ptr = subptr;
  80                     dict_bf_readp (dict->dbf, ptr, &p);
  81                     mid = lo = 0;
  82                     hi = DICT_nodir(p)-1;
  83                     indxp = (short*) ((char*) p+DICT_pagesize(dict)
  84                                       -sizeof(short));
  85                     continue;
  86                 }
  87             }
  88         }
  89         if (cmp < 0)
  90             lo = mid+1;
  91         else
  92             hi = mid-1;
  93     }
  94     return NULL;
  95 }
  96
  97 char *dict_lookup (Dict dict, Dict_char *p)
  98 {
  99     if (dict->head.last == 1)
 100         return NULL;
 101     return dict_look (dict, p);
 102 }
 103
 104