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