+++ /dev/null
-/************************************************************************************************
- IMP NOTE:
-
- All llookup hash function prototypes returns 0 or NULL when there is an error or else returns 1
- llookup hash is an array of lhashlistnode_t
- oid = mid = 0 in a given lhashlistnode_t for each bin in the hash table ONLY if the entry is empty =>
- the OID's can be any unsigned int except 0
-***************************************************************************************************/
-#include "llookup.h"
-
-extern lhashtable_t llookup; //Global Hash table
-
-// Creates a hash table with default size HASH_SIZE and an array of lhashlistnode_t
-unsigned int lhashCreate(unsigned int size, float loadfactor) {
- lhashlistnode_t *nodes;
- int i;
-
- // Allocate space for the hash table
- if((nodes = calloc(HASH_SIZE, sizeof(lhashlistnode_t))) == NULL) {
- printf("Calloc error %s %d\n", __FILE__, __LINE__);
- return 0;
- }
- for (i = 0; i < HASH_SIZE; i++)
- nodes[i].next = NULL;
-
- llookup.table = nodes;
- llookup.size = size;
- llookup.numelements = 0; // Initial number of elements in the hash
- llookup.loadfactor = loadfactor;
- return 1;
-}
-
-// Assign to oids to bins inside hash table
-unsigned int lhashFunction(unsigned int oid) {
- return( oid % (llookup.size));
-}
-
-// Insert oid and mid mapping into the hash table
-unsigned int lhashInsert(unsigned int oid, unsigned int mid) {
- unsigned int newsize;
- int index;
- lhashlistnode_t *ptr;
- lhashlistnode_t *node;
-
- if (llookup.numelements > (llookup.loadfactor * llookup.size)) {
- //Resize Table
- newsize = 2 * llookup.size + 1;
- lhashResize(newsize);
- }
- ptr = llookup.table;
- llookup.numelements++;
-
- index = lhashFunction(oid);
- if(ptr[index].next == NULL && ptr[index].oid == 0) { // Insert at the first position in the hashtable
- ptr[index].oid = oid;
- ptr[index].mid = mid;
- } else { // Insert in the linked list
- if ((node = calloc(1, sizeof(lhashlistnode_t))) == NULL) {
- printf("Calloc error %s, %d\n", __FILE__, __LINE__);
- return 0;
- }
- node->oid = oid;
- node->mid = mid;
- node->next = ptr[index].next;
- ptr[index].next = node;
- }
- return 1;
-}
-
-// Search for a value in the hash table
-unsigned int lhashSearch(unsigned int oid) {
- int index;
- lhashlistnode_t *ptr;
- lhashlistnode_t *tmp;
-
- ptr = llookup.table; // Address of the beginning of hash table
- index = lhashFunction(oid);
- tmp = &ptr[index];
- while(tmp != NULL) {
- if(tmp->oid == oid) {
- return tmp->mid;
- }
- tmp = tmp->next;
- }
- return 0;
-}
-
-// Remove an entry from the hash table
-unsigned int lhashRemove(unsigned int oid) {
- int index;
- lhashlistnode_t *curr, *prev, *tmp;
- lhashlistnode_t *ptr;
-
- ptr = llookup.table;
- index = lhashFunction(oid);
- prev = curr = &ptr[index];
-
- for (; curr != NULL; curr = curr->next) {
- if (curr->oid == oid) { // Find a match in the hash table
- llookup.numelements--; // Decrement the number of elements in the global hashtable
- if ((curr == &ptr[index]) && (curr->next == NULL)) { // Delete the first item inside the hashtable with no linked list of lhashlistnode_t
- curr->oid = 0;
- curr->mid = 0;
- } else if ((curr == &ptr[index]) && (curr->next != NULL)) { //Delete the first item with a linked list of lhashlistnode_t connected
- curr->oid = curr->next->oid;
- curr->mid = curr->next->mid;
- tmp = curr->next;
- curr->next = curr->next->next;
- free(tmp);
- } else { // Regular delete from linked listed
- prev->next = curr->next;
- free(curr);
- }
- return 1;
- }
- prev = curr;
- }
- return 0;
-}
-
-// Resize table
-unsigned int lhashResize(unsigned int newsize) {
- lhashlistnode_t *node, *curr, *next; // curr and next keep track of the current and the next lhashlistnodes in a linked list
- lhashtable_t oldtable;
- int i, isfirst; // Keeps track of the first element in the lhashlistnode_t for each bin in hashtable
-
- oldtable.table = llookup.table; // copy orginial lhashtable_t type to a new structure
- oldtable.size = llookup.size;
- oldtable.numelements = llookup.numelements;
- oldtable.loadfactor = llookup.loadfactor;
- if((node = calloc(newsize, sizeof(lhashlistnode_t))) == NULL) {
- printf("Calloc error %s %d\n", __FILE__, __LINE__);
- return 0;
- }
- llookup.table = node; //Update the global hashtable upon resize()
- llookup.size = newsize;
- llookup.numelements = 0;
-
- for(i = 0; i < oldtable.size; i++) {
- curr = next = &oldtable.table[i];
- isfirst = 1; //isfirst = true by default
- while (curr != NULL) {
- if (curr->oid == 0) { //Exit inner loop if there the first element for a given bin/index is NULL
- break; //oid = mid =0 for element if not present within the hash table
- }
- next = curr->next;
- lhashInsert(curr->oid, curr->mid); //Call hashInsert into the new resized table
- if (isfirst != 1) {
- free(curr); //free the linked list of lhashlistnode_t if not the first element in the hash table
- }
- isfirst = 0; //set isFirst = false inside inner loop
- curr = next;
- }
- }
- free(oldtable.table); //free the copied hashtable calloc-ed
- return 1;
-}
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