Programming Languages Research Group: Git - IRC.git/blob

   1  #include "clookup.h"
   2
   3 chashtable_t *chashCreate(unsigned int size, float loadfactor) {
   4         chashtable_t *ctable;
   5         chashlistnode_t *nodes;
   6         int i;
   7
   8         if((ctable = calloc(1, sizeof(chashtable_t))) == NULL) {
   9                 printf("Calloc error %s %d\n", __FILE__, __LINE__);
  10                 return NULL;
  11         }
  12
  13         // Allocate space for the hash table
  14         if((nodes = calloc(size, sizeof(chashlistnode_t))) == NULL) {
  15                 printf("Calloc error %s %d\n", __FILE__, __LINE__);
  16                 free(ctable);
  17                 return NULL;
  18         }
  19
  20         ctable->table = nodes;
  21         ctable->size = size;
  22         ctable->numelements = 0; // Initial number of elements in the hash
  23         ctable->loadfactor = loadfactor;
  24
  25         return ctable;
  26 }
  27
  28 //Finds the right bin in the hash table
  29 unsigned int chashFunction(chashtable_t *table, unsigned int key) {
  30         return ( key % (table->size));
  31 }
  32
  33 //Store objects and their pointers into hash
  34 unsigned int chashInsert(chashtable_t *table, unsigned int key, void *val) {
  35         unsigned int newsize;
  36         int index;
  37         chashlistnode_t *ptr, *node;
  38
  39         if(table->numelements > (table->loadfactor * table->size)) {
  40                 //Resize
  41                 newsize = 2 * table->size + 1;
  42                 chashResize(table,newsize);
  43         }
  44
  45         ptr = table->table;
  46         table->numelements++;
  47         index = chashFunction(table, key);
  48 #ifdef DEBUG
  49         printf("DEBUG -> index = %d, key = %d, val = %x\n", index, key, val);
  50 #endif
  51         if(ptr[index].next == NULL && ptr[index].key == 0) {    // Insert at the first position in the hashtable
  52                 ptr[index].key = key;
  53                 ptr[index].val = val;
  54         } else {                        // Insert in the beginning of linked list
  55                 if ((node = calloc(1, sizeof(chashlistnode_t))) == NULL) {
  56                         printf("Calloc error %s, %d\n", __FILE__, __LINE__);
  57                         return 1;
  58                 }
  59                 node->key = key;
  60                 node->val = val;
  61                 node->next = ptr[index].next;
  62                 ptr[index].next = node;
  63         }
  64         return 0;
  65 }
  66
  67 // Search for an address for a given oid
  68 void *chashSearch(chashtable_t *table, unsigned int key) {
  69         int index;
  70         chashlistnode_t *ptr, *node;
  71
  72         ptr = table->table;
  73         index = chashFunction(table, key);
  74         node = &ptr[index];
  75         while(node != NULL) {
  76                 if(node->key == key) {
  77                         return node->val;
  78                 }
  79                 node = node->next;
  80         }
  81         return NULL;
  82 }
  83
  84 unsigned int chashRemove(chashtable_t *table, unsigned int key) {
  85         int index;
  86         chashlistnode_t *curr, *prev;
  87         chashlistnode_t *ptr, *node;
  88
  89         ptr = table->table;
  90         index = chashFunction(table,key);
  91         curr = &ptr[index];
  92
  93         for (; curr != NULL; curr = curr->next) {
  94                 if (curr->key == key) {         // Find a match in the hash table
  95                         table->numelements--;  // Decrement the number of elements in the global hashtable
  96                         if ((curr == &ptr[index]) && (curr->next == NULL))  { // Delete the first item inside the hashtable with no linked list of chashlistnode_t
  97                                 curr->key = 0;
  98                                 curr->val = NULL;
  99                         } else if ((curr == &ptr[index]) && (curr->next != NULL)) { //Delete the first item with a linked list of chashlistnode_t  connected
 100                                 curr->key = curr->next->key;
 101                                 curr->val = curr->next->val;
 102                                 node = curr->next;
 103                                 curr->next = curr->next->next;
 104                                 free(node);
 105                         } else {                                                // Regular delete from linked listed
 106                                 prev->next = curr->next;
 107                                 free(curr);
 108                         }
 109                         return 0;
 110                 }
 111                 prev = curr;
 112         }
 113         return 1;
 114 }
 115
 116 unsigned int chashResize(chashtable_t *table, unsigned int newsize) {
 117         chashlistnode_t *node, *ptr, *curr, *next;      // curr and next keep track of the current and the next chashlistnodes in a linked list
 118         unsigned int oldsize;
 119         int isfirst;    // Keeps track of the first element in the chashlistnode_t for each bin in hashtable
 120         int i,index;
 121         chashlistnode_t *newnode;
 122
 123         ptr = table->table;
 124         oldsize = table->size;
 125
 126         if((node = calloc(newsize, sizeof(chashlistnode_t))) == NULL) {
 127                 printf("Calloc error %s %d\n", __FILE__, __LINE__);
 128                 return 1;
 129         }
 130
 131         table->table = node;            //Update the global hashtable upon resize()
 132         table->size = newsize;
 133         table->numelements = 0;
 134
 135         for(i = 0; i < oldsize; i++) {                  //Outer loop for each bin in hash table
 136                 curr = &ptr[i];
 137                 isfirst = 1;
 138                 while (curr != NULL) {                  //Inner loop to go through linked lists
 139                         if (curr->key == 0) {           //Exit inner loop if there the first element for a given bin/index is NULL
 140                                 break;                  //key = val =0 for element if not present within the hash table
 141                         }
 142                         next = curr->next;
 143
 144                         index = chashFunction(table, curr->key);
 145 #ifdef DEBUG
 146                         printf("DEBUG(resize) -> index = %d, key = %d, val = %x\n", index, curr->key, curr->val);
 147 #endif
 148                         // Insert into the new table
 149                         if(table->table[index].next == NULL && table->table[index].key == 0) {
 150                                 table->table[index].key = curr->key;
 151                                 table->table[index].val = curr->val;
 152                                 table->numelements++;
 153                         }else {
 154                                 if((newnode = calloc(1, sizeof(chashlistnode_t))) == NULL) {
 155                                         printf("Calloc error %s, %d\n", __FILE__, __LINE__);
 156                                         return 1;
 157                                 }
 158                                 newnode->key = curr->key;
 159                                 newnode->val = curr->val;
 160                                 newnode->next = table->table[index].next;
 161                                 table->table[index].next = newnode;
 162                                 table->numelements++;
 163                         }
 164
 165                         //free the linked list of chashlistnode_t if not the first element in the hash table
 166                         if (isfirst != 1) {
 167                                 free(curr);
 168                         }
 169
 170                         isfirst = 0;
 171                         curr = next;
 172                 }
 173         }
 174
 175         free(ptr);              //Free the memory of the old hash table
 176         return 0;
 177 }
 178
 179 //Delete the entire hash table
 180 void chashDelete(chashtable_t *table) {
 181         int i, isFirst;
 182         chashlistnode_t *ptr, *curr, *next;
 183         ptr = table->table;
 184
 185         for(i=0 ; i<table->size ; i++) {
 186                 curr = &ptr[i];
 187                 isFirst = 1 ;
 188                 while(curr  != NULL) {
 189                         next = curr->next;
 190                         if(isFirst != 1) {
 191                                 free(curr);
 192                         }
 193                         isFirst = 0;
 194                         curr = next;
 195                 }
 196         }
 197
 198         free(ptr);
 199         free(table);
 200         table = NULL;
 201 }