wmmp3/song_hash.c

   1 #include "song_hash.h"
   2
   3 #define HASH_TABLE_SIZE 11
   4
   5 struct hash_elt *Table[HASH_TABLE_SIZE];
   6
   7 int hash_fn(int num);
   8 void free_elt(struct hash_elt *elt);
   9
  10 int hash_fn(int num)
  11 {
  12         return (num % HASH_TABLE_SIZE);
  13 }
  14
  15 void insert_song(int track_num, char *title, char *filename)
  16 {
  17         int hash_value;
  18         struct hash_elt *hash_list;
  19         struct hash_elt *new_elt;
  20
  21
  22         new_elt = (struct hash_elt *) malloc(sizeof(struct hash_elt));
  23         if (new_elt != NULL)
  24         {
  25                 new_elt->track_num = track_num;
  26                 new_elt->title = (char *)strdup(title);
  27                 new_elt->filename = (char *)strdup(filename);
  28                 new_elt->next = NULL;
  29         }
  30
  31         hash_value = hash_fn(track_num);
  32         hash_list = Table[hash_value];
  33         if (hash_list != NULL) {
  34                 while (hash_list->next != NULL) {
  35                         hash_list = hash_list->next;
  36                 }
  37                 hash_list->next = new_elt;
  38         }
  39         else
  40         {
  41                 Table[hash_value] = new_elt;
  42         }
  43 }
  44
  45 struct hash_elt *get_song(int track_num)
  46 {
  47         int hash_value;
  48         struct hash_elt *hash_list;
  49
  50         hash_value = hash_fn(track_num);
  51         hash_list = Table[hash_value];
  52         if (hash_list) {
  53             while ((hash_list->track_num != track_num) &&
  54                    (hash_list->next != NULL)) {
  55                 hash_list = hash_list->next;
  56             }
  57             if (hash_list->track_num == track_num) {
  58                 return hash_list;
  59             }
  60             else {
  61                 return NULL;
  62             }
  63         }
  64         else {
  65             return NULL;
  66         }
  67 }
  68
  69 void free_elt(struct hash_elt *elt)
  70 {
  71         if (elt != NULL)
  72         {
  73                 if (elt->next != NULL) {
  74                         free_elt(elt->next);
  75                 }
  76                 free(elt);
  77         }
  78 }
  79
  80 void empty_hash()
  81 {
  82         int i;
  83
  84         for (i = 0; i < HASH_TABLE_SIZE; i++) {
  85                 free_elt(Table[i]);
  86                 Table[i] = NULL;
  87         }
  88 }
  89
  90 void print_hash()
  91 {
  92         int i;
  93         struct hash_elt *hash_list;
  94
  95         for (i = 0; i < HASH_TABLE_SIZE; i++) {
  96                 printf("%d:\n", i);
  97                 hash_list = Table[i];
  98                 while (hash_list != NULL) {
  99                         printf("\t%d: %s\n",
 100                                hash_list->track_num,
 101                                hash_list->title);
 102                         hash_list = hash_list->next;
 103                 }
 104         }
 105
 106 }
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