wmmp3/song_hash.c

   1 #include <stdlib.h>
   2 #include <string.h>
   3 #include "song_hash.h"
   4
   5 #define HASH_TABLE_SIZE 11
   6
   7 struct hash_elt *Table[HASH_TABLE_SIZE];
   8
   9 int hash_fn(int num);
  10 void free_elt(struct hash_elt *elt);
  11
  12 int hash_fn(int num)
  13 {
  14         return (num % HASH_TABLE_SIZE);
  15 }
  16
  17 void insert_song(int track_num, char *title, char *filename)
  18 {
  19         int hash_value;
  20         struct hash_elt *hash_list;
  21         struct hash_elt *new_elt;
  22
  23
  24         new_elt = (struct hash_elt *) malloc(sizeof(struct hash_elt));
  25         if (new_elt != NULL)
  26         {
  27                 new_elt->track_num = track_num;
  28                 new_elt->title = (char *)strdup(title);
  29                 new_elt->filename = (char *)strdup(filename);
  30                 new_elt->next = NULL;
  31         }
  32
  33         hash_value = hash_fn(track_num);
  34         hash_list = Table[hash_value];
  35         if (hash_list != NULL) {
  36                 while (hash_list->next != NULL) {
  37                         hash_list = hash_list->next;
  38                 }
  39                 hash_list->next = new_elt;
  40         }
  41         else
  42         {
  43                 Table[hash_value] = new_elt;
  44         }
  45 }
  46
  47 struct hash_elt *get_song(int track_num)
  48 {
  49         int hash_value;
  50         struct hash_elt *hash_list;
  51
  52         hash_value = hash_fn(track_num);
  53         hash_list = Table[hash_value];
  54         if (hash_list) {
  55             while ((hash_list->track_num != track_num) &&
  56                    (hash_list->next != NULL)) {
  57                 hash_list = hash_list->next;
  58             }
  59             if (hash_list->track_num == track_num) {
  60                 return hash_list;
  61             }
  62             else {
  63                 return NULL;
  64             }
  65         }
  66         else {
  67             return NULL;
  68         }
  69 }
  70
  71 void free_elt(struct hash_elt *elt)
  72 {
  73         if (elt != NULL)
  74         {
  75                 if (elt->next != NULL) {
  76                         free_elt(elt->next);
  77                 }
  78                 free(elt);
  79         }
  80 }
  81
  82 void empty_hash()
  83 {
  84         int i;
  85
  86         for (i = 0; i < HASH_TABLE_SIZE; i++) {
  87                 free_elt(Table[i]);
  88                 Table[i] = NULL;
  89         }
  90 }
  91
  92 void print_hash()
  93 {
  94         int i;
  95         struct hash_elt *hash_list;
  96
  97         for (i = 0; i < HASH_TABLE_SIZE; i++) {
  98                 printf("%d:\n", i);
  99                 hash_list = Table[i];
 100                 while (hash_list != NULL) {
 101                         printf("\t%d: %s\n",
 102                                hash_list->track_num,
 103                                hash_list->title);
 104                         hash_list = hash_list->next;
 105                 }
 106         }
 107
 108 }
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