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 1.5  1995-09-04 09:09:15  adam
   8  * String arg in lookup is const.
   9  *
  10  * Revision 1.4  1994/10/05  12:16:51  adam
  11  * Pagesize is a resource now.
  12  *
  13  * Revision 1.3  1994/09/26  10:17:25  adam
  14  * Minor changes.
  15  *
  16  * Revision 1.2  1994/09/16  15:39:14  adam
  17  * Initial code of lookup - not tested yet.
  18  *
  19  * Revision 1.1  1994/08/16  16:26:48  adam
  20  * Added dict.
  21  *
  22  */
  23
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <stdio.h>
  27 #include <assert.h>
  28
  29 #include <dict.h>
  30
  31 static char *dict_look (Dict dict, const Dict_char *str)
  32 {
  33     Dict_ptr ptr = 1;
  34     int mid, lo, hi;
  35     int cmp;
  36     void *p;
  37     short *indxp;
  38     char *info;
  39
  40     dict_bf_readp (dict->dbf, ptr, &p);
  41     mid = lo = 0;
  42     hi = DICT_nodir(p)-1;
  43     indxp = (short*) ((char*) p+DICT_pagesize(dict)-sizeof(short));
  44     while (lo <= hi)
  45     {
  46         mid = (lo+hi)/2;
  47         if (indxp[-mid] > 0)
  48         {
  49             /* string (Dict_char *) DICT_EOS terminated */
  50             /* unsigned char        length of information */
  51             /* char *               information */
  52             info = (char*)p + indxp[-mid];
  53             cmp = dict_strcmp((Dict_char*) info, str);
  54             if (!cmp)
  55                 return info+(dict_strlen (info)+1)*sizeof(Dict_char);
  56         }
  57         else
  58         {
  59             Dict_char dc;
  60             Dict_ptr subptr;
  61
  62             /* Dict_ptr             subptr */
  63             /* Dict_char            sub char */
  64             /* unsigned char        length of information */
  65             /* char *               information */
  66             info = (char*)p - indxp[-mid];
  67             memcpy (&dc, info+sizeof(Dict_ptr), sizeof(Dict_char));
  68             cmp = dc- *str;
  69             if (!cmp)
  70             {
  71                 memcpy (&subptr, info, sizeof(Dict_ptr));
  72                 if (*++str == DICT_EOS)
  73                 {
  74                     if (info[sizeof(Dict_ptr)+sizeof(Dict_char)])
  75                         return info+sizeof(Dict_ptr)+sizeof(Dict_char);
  76                     return NULL;
  77                 }
  78                 else
  79                 {
  80                     if (subptr == 0)
  81                         return NULL;
  82                     ptr = subptr;
  83                     dict_bf_readp (dict->dbf, ptr, &p);
  84                     mid = lo = 0;
  85                     hi = DICT_nodir(p)-1;
  86                     indxp = (short*) ((char*) p+DICT_pagesize(dict)
  87                                       -sizeof(short));
  88                     continue;
  89                 }
  90             }
  91         }
  92         if (cmp < 0)
  93             lo = mid+1;
  94         else
  95             hi = mid-1;
  96     }
  97     return NULL;
  98 }
  99
 100 char *dict_lookup (Dict dict, const Dict_char *p)
 101 {
 102     if (dict->head.last == 1)
 103         return NULL;
 104     return dict_look (dict, p);
 105 }
 106
 107