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-rw-r--r--Makefile24
-rw-r--r--hashfuncs.c163
-rw-r--r--hashfuncs.h23
-rw-r--r--hashtbl.c228
-rw-r--r--hashtbl.h31
5 files changed, 469 insertions, 0 deletions
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..3e20c8c
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,24 @@
+PROG = hashtbl
+OBJS = $(PROG).o hashfuncs.o
+CC = gcc
+DBGFLAGS = -g -O0
+ifdef DEBUG
+ CFLAGS = $(DBGFLAGS) -Wall -std=c99
+else
+ CFLAGS = -Wall -std=c99 -O2 -march=native -mtune=native
+endif
+LDFLAGS = -lm
+
+$(PROG): $(OBJS)
+ $(CC) $(LDFLAGS) $(OBJS) -o $(PROG)
+
+$(PROG).o: $(PROG).c hashtbl.h hashfuncs.h
+ $(CC) -c $(CFLAGS) $(PROG).c
+
+hashfuncs.o: hashfuncs.c hashfuncs.h
+ $(CC) -c $(CFLAGS) hashfuncs.c
+
+.PHONY: clean
+
+clean:
+ rm -f *.o ./$(PROG)
diff --git a/hashfuncs.c b/hashfuncs.c
new file mode 100644
index 0000000..01a1be1
--- /dev/null
+++ b/hashfuncs.c
@@ -0,0 +1,163 @@
+/* hashfuncs.c
+ *
+ * Hash Functions
+ *
+ * notes: aphash may not be correct
+ *
+ */
+
+#include "hashfuncs.h"
+
+/* does not mod by the size of the hash table, simple and clever,
+ * this allows seamless retrieval of collided elements */
+unsigned int defaulthash(const char *key)
+{
+ unsigned int hash = 0;
+
+ for ( ; *key; key++)
+ hash += (unsigned char) *key;
+
+ return hash;
+}
+
+unsigned int rshash(const char *key)
+{
+ unsigned int b = 378551;
+ unsigned int a = 63689;
+ unsigned int hash = 0;
+
+ for ( ; *key; key++)
+ {
+ hash = hash * a + (*key);
+ a = a * b;
+ }
+
+ return hash;
+}
+
+unsigned int jshash(const char *key)
+{
+ unsigned int hash = 1315423911;
+
+ for ( ; *key; key++)
+ hash ^= ((hash << 5) + ((unsigned char) (*key)) + (hash >> 2));
+
+ return hash;
+}
+
+unsigned int pjwhash(const char *key)
+{
+ const unsigned int BitsInUnsignedInt = (unsigned int) (sizeof(unsigned int) * 8);
+ const unsigned int ThreeQuarters = (unsigned int) ((BitsInUnsignedInt * 3) / 4);
+ const unsigned int OneEighth = (unsigned int) (BitsInUnsignedInt / 8);
+ const unsigned int HighBits = (unsigned int) (0xFFFFFFFF) << (BitsInUnsignedInt - OneEighth);
+ unsigned int hash = 0;
+ unsigned int test = 0;
+
+ for ( ; *key; key++)
+ {
+ hash = (hash << OneEighth) + (*key);
+ if ((test = hash & HighBits) != 0)
+ hash = (( hash ^ (test >> ThreeQuarters)) & (~HighBits));
+ }
+
+ return hash;
+}
+
+unsigned int elfhash(const char *key)
+{
+ unsigned int hash = 0;
+ unsigned int x = 0;
+
+ for ( ; *key; key++)
+ {
+ hash = (hash << 4) + (*key);
+
+ if ((x = hash & 0xF0000000L) != 0)
+ hash ^= (x >> 24);
+
+ hash &= ~x;
+ }
+
+ return hash;
+}
+
+unsigned int bkdrhash(const char *key)
+{
+ unsigned int seed = 131; /* 31 131 1313 13131 131313 etc.. */
+ unsigned int hash = 0;
+
+ for ( ; *key; key++)
+ hash = (hash * seed) + (*key);
+
+ return hash;
+}
+
+unsigned int sdbmhash(const char *key)
+{
+ unsigned int hash = 0;
+
+ for ( ; *key; key++)
+ hash = (*key) + (hash << 6) + (hash << 16) - hash;
+
+ return hash;
+}
+
+unsigned int djbhash(const char *key)
+{
+ unsigned int hash = 5381;
+
+ for ( ; *key; key++)
+ hash = ((hash << 5) + hash) + (*key);
+
+ return hash;
+}
+
+unsigned int dekhash(const char *key)
+{
+ unsigned int hash = strlen(key);
+
+ for ( ; *key; key++)
+ hash = ((hash << 5) ^ (hash >> 27)) ^ (*key);
+
+ return hash;
+}
+
+unsigned int bphash(const char *key)
+{
+ unsigned int hash = 0;
+
+ for ( ; *key; key++)
+ hash = hash << 7 ^ (*key);
+
+ return hash;
+}
+
+unsigned int fnvhash(const char *key)
+{
+ const unsigned int fnv_prime = 0x811C9DC5;
+ unsigned int hash = 0;
+
+ for ( ; *key; key++)
+ {
+ hash *= fnv_prime;
+ hash ^= (*key);
+ }
+
+ return hash;
+}
+
+unsigned int aphash(const char *key)
+{
+ unsigned int hash = 0xAAAAAAAA;
+ unsigned int i = strlen(key);
+
+ for ( ; *key; key++)
+ {
+ hash ^= ((i & 1) == 0) ? ( (hash << 7) ^ (*key) * (hash >> 3)) :
+ (~((hash << 11) + ((*key) ^ (hash >> 5))));
+ }
+
+ return hash;
+}
+
diff --git a/hashfuncs.h b/hashfuncs.h
new file mode 100644
index 0000000..f344810
--- /dev/null
+++ b/hashfuncs.h
@@ -0,0 +1,23 @@
+#ifndef _HASHFUNCS_H_
+#define _HASHFUNCS_H_
+
+#include <stdio.h>
+#include <string.h>
+
+/* typedef unsigned int (*hash_func)(const char *); */
+
+unsigned int defaulthash(const char *);
+unsigned int rshash(const char *);
+unsigned int jshash(const char *);
+unsigned int pjwhash(const char *);
+unsigned int elfhash(const char *);
+unsigned int bkdrhash(const char *);
+unsigned int sdbmhash(const char *);
+unsigned int djbhash(const char *);
+unsigned int dekhash(const char *);
+unsigned int bphash(const char *);
+unsigned int fnvhash(const char *);
+unsigned int aphash(const char *);
+
+#endif
+
diff --git a/hashtbl.c b/hashtbl.c
new file mode 100644
index 0000000..f26a8dd
--- /dev/null
+++ b/hashtbl.c
@@ -0,0 +1,228 @@
+/* hashtbl.c
+ *
+ * Hash Table
+ *
+ */
+
+#include "hashtbl.h"
+#include "hashfuncs.h"
+
+char *strdup(const char *s)
+{
+ char *b;
+ if (!(b = malloc(strlen(s) + 1)))
+ return NULL;
+ strcpy(b, s);
+
+ return b;
+}
+
+HASHTBL *hashtbl_create(size_t size, unsigned int (*hashfunc)(const char *))
+{
+ HASHTBL *hashtbl;
+
+ if (!(hashtbl = malloc(sizeof(HASHTBL))))
+ return NULL;
+
+ /* pointer array of nodes */
+ if (!(hashtbl->nodes = calloc(size, sizeof(struct hashnode_s*))))
+ {
+ free(hashtbl);
+ return NULL;
+ }
+
+ hashtbl->size = size;
+
+ if (hashfunc)
+ hashtbl->hashfunc = hashfunc;
+ else
+ hashtbl->hashfunc = aphash;
+
+ return hashtbl;
+}
+
+void hashtbl_destroy(HASHTBL *hashtbl)
+{
+ size_t n;
+ struct hashnode_s *node, *oldnode;
+
+ for (n = 0; n<hashtbl->size; ++n) {
+ node = hashtbl->nodes[n];
+ while (node) {
+ free(node->key);
+ oldnode = node;
+ node = node->next;
+ free(oldnode);
+ }
+ }
+ free(hashtbl->nodes);
+ free(hashtbl);
+}
+
+int hashtbl_insert(HASHTBL *hashtbl, const char *key, void *data)
+{
+ struct hashnode_s *head;
+ size_t hash = hashtbl->hashfunc(key) % hashtbl->size;
+
+/* fprintf(stderr, "hashtbl_insert() key = %s, hash = %d, data = %s\n", key, hash, (char*)data); */
+
+ head = hashtbl->nodes[hash];
+ while (head)
+ {
+ if (!strcmp(head->key, key))
+ {
+ /* update the data in currently existing node */
+ head->data = data;
+ return 0;
+ }
+
+ head = head->next;
+ }
+
+ /* if we get here, it means that this is the first node at particular index
+ * or we are appending new node to the end of the linked list */
+ if (!(head = malloc(sizeof(struct hashnode_s))))
+ return -1;
+
+ if (!(head->key = strdup(key)))
+ {
+ free(head);
+ return -1;
+ }
+
+ head->data = data;
+ head->next = hashtbl->nodes[hash];
+
+ /* update head ptr */
+ hashtbl->nodes[hash] = head;
+
+ return 0;
+}
+
+int hashtbl_remove(HASHTBL *hashtbl, const char *key)
+{
+ struct hashnode_s *node, *prevnode = NULL;
+ size_t hash = hashtbl->hashfunc(key) % hashtbl->size;
+
+ node = hashtbl->nodes[hash];
+ while (node)
+ {
+ if (!strcmp(node->key, key))
+ {
+ free(node->key);
+ if (prevnode)
+ prevnode->next = node->next;
+ else
+ hashtbl->nodes[hash] = node->next;
+
+ free(node);
+
+ return 0;
+ }
+
+ prevnode = node;
+ node = node->next;
+ }
+
+ return -1;
+}
+
+
+void *hashtbl_get(HASHTBL *hashtbl, const char *key)
+{
+ struct hashnode_s *head;
+ size_t hash = hashtbl->hashfunc(key) % hashtbl->size;
+
+/* fprintf(stderr, "hashtbl_get() key = %s, hash = %d\n", key, hash);*/
+
+ head = hashtbl->nodes[hash];
+ while (head)
+ {
+ /* return data only when keys match */
+ if (!strcmp(head->key, key))
+ return head->data;
+
+ head = head->next;
+ }
+
+ return NULL;
+}
+
+int hashtbl_resize(HASHTBL *hashtbl, size_t size)
+{
+ HASHTBL newtbl;
+ size_t n;
+ struct hashnode_s *node,*next;
+
+ newtbl.size = size;
+ newtbl.hashfunc = hashtbl->hashfunc;
+
+ if (!(newtbl.nodes = calloc(size, sizeof(struct hashnode_s*)))) return -1;
+
+ for (n = 0; n<hashtbl->size; ++n) {
+ for (node = hashtbl->nodes[n]; node; node = next) {
+ next = node->next;
+ hashtbl_insert(&newtbl, node->key, node->data);
+ hashtbl_remove(hashtbl, node->key);
+
+ }
+ }
+
+ free(hashtbl->nodes);
+ hashtbl->size = newtbl.size;
+ hashtbl->nodes = newtbl.nodes;
+
+ return 0;
+}
+
+int main(void)
+{
+ char *key = "abcdefghijklmnopqrstuvwxyz1234567890";
+
+ (void) printf("Hash Functions\n");
+ (void) printf("Key: %s\n\n", key);
+ (void) printf("ASCII default hash function value: %u\n", defaulthash(key));
+ (void) printf("RS hash function value: %u\n", rshash(key));
+ (void) printf("JS hash function value: %u\n", jshash(key));
+ (void) printf("PJW hash function value: %u\n", pjwhash(key));
+ (void) printf("ELF hash function value: %u\n", elfhash(key));
+ (void) printf("BKDR hash function value: %u\n", bkdrhash(key));
+ (void) printf("SDBM hash function value: %u\n", sdbmhash(key));
+ (void) printf("DJB hash function value: %u\n", djbhash(key));
+ (void) printf("DEK hash function value: %u\n", dekhash(key));
+ (void) printf("BP hash function value: %u\n", bphash(key));
+ (void) printf("FNV hash function value: %u\n", fnvhash(key));
+ (void) printf("AP hash function value: %u\n", aphash(key));
+ (void) puts("");
+
+ HASHTBL *hashtbl;
+ char *italy, *spain;
+
+ hashtbl = hashtbl_create(16, NULL);
+ if (hashtbl == NULL)
+ {
+ fprintf(stderr, "error: hashtbl_create() failed\n");
+ exit(-1);
+ }
+
+ hashtbl_insert(hashtbl, "France", "Paris");
+ hashtbl_insert(hashtbl, "England", "London");
+ hashtbl_insert(hashtbl, "Sweden", "Stockholm");
+ hashtbl_insert(hashtbl, "Germany", "Berlin");
+ hashtbl_insert(hashtbl, "Norway", "Oslo");
+ hashtbl_insert(hashtbl, "Italy", "Rome");
+ hashtbl_insert(hashtbl, "Spain", "Madrid");
+ hashtbl_insert(hashtbl, "Estonia", "Tallinn");
+ hashtbl_insert(hashtbl, "Netherlands", "Amsterdam");
+ hashtbl_insert(hashtbl, "Ireland", "Dublin");
+
+ italy = hashtbl_get(hashtbl, "Italy");
+ (void) printf("Italy: %s\n", italy ? italy : "");
+ spain = hashtbl_get(hashtbl, "Spain");
+ (void) printf("Spain: %s\n", spain ? spain : "");
+
+ hashtbl_destroy(hashtbl);
+
+ return 0;
+}
+
diff --git a/hashtbl.h b/hashtbl.h
new file mode 100644
index 0000000..70428f8
--- /dev/null
+++ b/hashtbl.h
@@ -0,0 +1,31 @@
+#ifndef HASHTBL_H_
+#define HASHTBL_H_
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+typedef struct hashtbl
+{
+ size_t size;
+ struct hashnode_s **nodes;
+ unsigned int (*hashfunc)(const char *);
+} HASHTBL;
+
+struct hashnode_s {
+ char *key;
+ void *data;
+ struct hashnode_s *next;
+};
+
+/* function prototypes */
+char *strdup(const char *);
+HASHTBL *hashtbl_create(size_t, unsigned int (*hashfunc)(const char *));
+void hashtbl_destroy(HASHTBL *);
+int hashtbl_insert(HASHTBL *, const char *, void *);
+int hashtbl_remove(HASHTBL *, const char *);
+void *hashtbl_get(HASHTBL *, const char *);
+int hashtbl_resize(HASHTBL *, size_t);
+
+#endif
+
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