/* This is a public domain general purpose hash table package written by Peter Moore @ UCB. */

/* static	char	sccsid[] = "@(#) st.c 5.1 89/12/14 Crucible"; */

#include <stdio.h>
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#include <string.h>

#ifdef NOT_RUBY
#include "regint.h"
#include "st.h"
#else
#include "ruby/config.h"
#include "ruby/defines.h"
#include "ruby/st.h"
#endif

typedef struct st_table_entry st_table_entry;

struct st_table_entry {
    unsigned int hash;
    st_data_t key;
    st_data_t record;
    st_table_entry *next;
    st_table_entry *fore, *back;
};

#define ST_DEFAULT_MAX_DENSITY 5
#define ST_DEFAULT_INIT_TABLE_SIZE 11

    /*
     * DEFAULT_MAX_DENSITY is the default for the largest we allow the
     * average number of items per bin before increasing the number of
     * bins
     *
     * DEFAULT_INIT_TABLE_SIZE is the default for the number of bins
     * allocated initially
     *
     */

static const struct st_hash_type type_numhash = {
    st_numcmp,
    st_numhash,
};

/* extern int strcmp(const char *, const char *); */
static int strhash(const char *);
static const struct st_hash_type type_strhash = {
    strcmp,
    strhash,
};

static void rehash(st_table *);

#ifdef RUBY
#define malloc xmalloc
#define calloc xcalloc
#endif

#define alloc(type) (type*)malloc((size_t)sizeof(type))
#define Calloc(n,s) (char*)calloc((n),(s))

#define EQUAL(table,x,y) ((x)==(y) || (*table->type->compare)((x),(y)) == 0)

#define do_hash(key,table) (unsigned int)(*(table)->type->hash)((key))
#define do_hash_bin(key,table) (do_hash(key, table)%(table)->num_bins)

/*
 * MINSIZE is the minimum size of a dictionary.
 */

#define MINSIZE 8

/*
Table of prime numbers 2^n+a, 2<=n<=30.
*/
static long primes[] = {
	8 + 3,
	16 + 3,
	32 + 5,
	64 + 3,
	128 + 3,
	256 + 27,
	512 + 9,
	1024 + 9,
	2048 + 5,
	4096 + 3,
	8192 + 27,
	16384 + 43,
	32768 + 3,
	65536 + 45,
	131072 + 29,
	262144 + 3,
	524288 + 21,
	1048576 + 7,
	2097152 + 17,
	4194304 + 15,
	8388608 + 9,
	16777216 + 43,
	33554432 + 35,
	67108864 + 15,
	134217728 + 29,
	268435456 + 3,
	536870912 + 11,
	1073741824 + 85,
	0
};

static int
new_size(int size)
{
    int i;

#if 0
    for (i=3; i<31; i++) {
	if ((1<<i) > size) return 1<<i;
    }
    return -1;
#else
    int newsize;

    for (i = 0, newsize = MINSIZE;
	 i < (int )(sizeof(primes)/sizeof(primes[0]));
	 i++, newsize <<= 1)
    {
	if (newsize > size) return primes[i];
    }
    /* Ran out of polynomials */
    return -1;			/* should raise exception */
#endif
}

#ifdef HASH_LOG
static int collision = 0;
static int init_st = 0;

static void
stat_col()
{
    FILE *f = fopen("/tmp/col", "w");
    fprintf(f, "collision: %d\n", collision);
    fclose(f);
}
#endif

st_table*
st_init_table_with_size(const struct st_hash_type *type, int size)
{
    st_table *tbl;

#ifdef HASH_LOG
    if (init_st == 0) {
	init_st = 1;
	atexit(stat_col);
    }
#endif

    size = new_size(size);	/* round up to prime number */

    tbl = alloc(st_table);
    tbl->type = type;
    tbl->num_entries = 0;
    tbl->num_bins = size;
    tbl->bins = (st_table_entry **)Calloc(size, sizeof(st_table_entry*));
    tbl->head = 0;

    return tbl;
}

st_table*
st_init_table(const struct st_hash_type *type)
{
    return st_init_table_with_size(type, 0);
}

st_table*
st_init_numtable(void)
{
    return st_init_table(&type_numhash);
}

st_table*
st_init_numtable_with_size(int size)
{
    return st_init_table_with_size(&type_numhash, size);
}

st_table*
st_init_strtable(void)
{
    return st_init_table(&type_strhash);
}

st_table*
st_init_strtable_with_size(int size)
{
    return st_init_table_with_size(&type_strhash, size);
}

void
st_clear(st_table *table)
{
    register st_table_entry *ptr, *next;
    int i;

    for(i = 0; i < table->num_bins; i++) {
	ptr = table->bins[i];
	table->bins[i] = 0;
	while (ptr != 0) {
	    next = ptr->next;
	    free(ptr);
	    ptr = next;
	}
    }
    table->num_entries = 0;
    table->head = 0;
}

void
st_free_table(st_table *table)
{
    st_clear(table);
    free(table->bins);
    free(table);
}

#define PTR_NOT_EQUAL(table, ptr, hash_val, key) \
((ptr) != 0 && (ptr->hash != (hash_val) || !EQUAL((table), (key), (ptr)->key)))

#ifdef HASH_LOG
#define COLLISION collision++
#else
#define COLLISION
#endif

#define FIND_ENTRY(table, ptr, hash_val, bin_pos) do {\
    bin_pos = hash_val%(table)->num_bins;\
    ptr = (table)->bins[bin_pos];\
    if (PTR_NOT_EQUAL(table, ptr, hash_val, key)) {\
	COLLISION;\
	while (PTR_NOT_EQUAL(table, ptr->next, hash_val, key)) {\
	    ptr = ptr->next;\
	}\
	ptr = ptr->next;\
    }\
} while (0)

int
st_lookup(st_table *table, register st_data_t key, st_data_t *value)
{
    unsigned int hash_val, bin_pos;
    register st_table_entry *ptr;

    hash_val = do_hash(key, table);
    FIND_ENTRY(table, ptr, hash_val, bin_pos);

    if (ptr == 0) {
	return 0;
    }
    else {
	if (value != 0)  *value = ptr->record;
	return 1;
    }
}

#define ADD_DIRECT(table, key, value, hash_val, bin_pos)\
do {\
    st_table_entry *entry, *head;\
    if (table->num_entries/(table->num_bins) > ST_DEFAULT_MAX_DENSITY) {\
	rehash(table);\
        bin_pos = hash_val % table->num_bins;\
    }\
    \
    entry = alloc(st_table_entry);\
    \
    entry->hash = hash_val;\
    entry->key = key;\
    entry->record = value;\
    entry->next = table->bins[bin_pos];\
    if ((head = table->head) != 0) {\
	entry->fore = head;\
	(entry->back = head->back)->fore = entry;\
	head->back = entry;\
    }\
    else {\
	table->head = entry->fore = entry->back = entry;\
    }\
    table->bins[bin_pos] = entry;\
    table->num_entries++;\
} while (0)

int
st_insert(register st_table *table, register st_data_t key, st_data_t value)
{
    unsigned int hash_val, bin_pos;
    register st_table_entry *ptr;

    hash_val = do_hash(key, table);
    FIND_ENTRY(table, ptr, hash_val, bin_pos);

    if (ptr == 0) {
	ADD_DIRECT(table, key, value, hash_val, bin_pos);
	return 0;
    }
    else {
	ptr->record = value;
	return 1;
    }
}

void
st_add_direct(st_table *table, st_data_t key, st_data_t value)
{
    unsigned int hash_val, bin_pos;

    hash_val = do_hash(key, table);
    bin_pos = hash_val % table->num_bins;
    ADD_DIRECT(table, key, value, hash_val, bin_pos);
}

static void
rehash(register st_table *table)
{
    register st_table_entry *ptr, **new_bins;
    int i, new_num_bins;
    unsigned int hash_val;

    new_num_bins = new_size(table->num_bins+1);
    new_bins = (st_table_entry**)
	xrealloc(table->bins, new_num_bins * sizeof(st_table_entry*));
    for (i = 0; i < new_num_bins; ++i) new_bins[i] = 0;
    table->num_bins = new_num_bins;
    table->bins = new_bins;

    if ((ptr = table->head) != 0) {
	do {
	    hash_val = ptr->hash % new_num_bins;
	    ptr->next = new_bins[hash_val];
	    new_bins[hash_val] = ptr;
	} while ((ptr = ptr->fore) != table->head);
    }
}

st_table*
st_copy(st_table *old_table)
{
    st_table *new_table;
    st_table_entry *ptr, *entry, *prev, **tail;
    int num_bins = old_table->num_bins;
    unsigned int hash_val;

    new_table = alloc(st_table);
    if (new_table == 0) {
	return 0;
    }

    *new_table = *old_table;
    new_table->bins = (st_table_entry**)
	Calloc((unsigned)num_bins, sizeof(st_table_entry*));

    if (new_table->bins == 0) {
	free(new_table);
	return 0;
    }

    if ((ptr = old_table->head) != 0) {
	prev = 0;
	tail = &new_table->head;
	do {
	    entry = alloc(st_table_entry);
	    if (entry == 0) {
		st_free_table(new_table);
		return 0;
	    }
	    *entry = *ptr;
	    hash_val = entry->hash % num_bins;
	    entry->next = new_table->bins[hash_val];
	    new_table->bins[hash_val] = entry;
	    entry->back = prev;
	    *tail = prev = entry;
	    tail = &entry->fore;
	} while ((ptr = ptr->fore) != old_table->head);
	entry = new_table->head;
	entry->back = prev;
	*tail = entry;
    }

    return new_table;
}

#define REMOVE_ENTRY(table, ptr) do					\
    {									\
	if (ptr == ptr->fore) {						\
	    table->head = 0;						\
	}								\
	else {								\
	    st_table_entry *fore = ptr->fore, *back = ptr->back;	\
	    fore->back = back;						\
	    back->fore = fore;						\
	    if (ptr == table->head) table->head = fore;			\
	}								\
	table->num_entries--;						\
    } while (0)

int
st_delete(register st_table *table, register st_data_t *key, st_data_t *value)
{
    unsigned int hash_val;
    st_table_entry **prev;
    register st_table_entry *ptr;

    hash_val = do_hash_bin(*key, table);

    for (prev = &table->bins[hash_val]; (ptr = *prev) != 0; prev = &ptr->next) {
	if (EQUAL(table, *key, ptr->key)) {
	    *prev = ptr->next;
	    REMOVE_ENTRY(table, ptr);
	    if (value != 0) *value = ptr->record;
	    *key = ptr->key;
	    free(ptr);
	    return 1;
	}
    }

    if (value != 0) *value = 0;
    return 0;
}

int
st_delete_safe(register st_table *table, register st_data_t *key, st_data_t *value, st_data_t never)
{
    unsigned int hash_val;
    register st_table_entry *ptr;

    hash_val = do_hash_bin(*key, table);
    ptr = table->bins[hash_val];

    for (; ptr != 0; ptr = ptr->next) {
	if ((ptr->key != never) && EQUAL(table, ptr->key, *key)) {
	    REMOVE_ENTRY(table, ptr);
	    *key = ptr->key;
	    if (value != 0) *value = ptr->record;
	    ptr->key = ptr->record = never;
	    return 1;
	}
    }

    if (value != 0) *value = 0;
    return 0;
}

void
st_cleanup_safe(st_table *table, st_data_t never)
{
    st_table_entry *ptr, **last, *tmp;
    int i;

    for (i = 0; i < table->num_bins; i++) {
	ptr = *(last = &table->bins[i]);
	while (ptr != 0) {
	    if (ptr->key == never) {
		tmp = ptr;
		*last = ptr = ptr->next;
		free(tmp);
	    }
	    else {
		ptr = *(last = &ptr->next);
	    }
	}
    }
}

int
st_foreach(st_table *table, int (*func)(ANYARGS), st_data_t arg)
{
    st_table_entry *ptr, **last, *tmp;
    enum st_retval retval;
    int i, end;

    if ((ptr = table->head) != 0) {
	do {
	    end = ptr->fore == table->head;
	    retval = (*func)(ptr->key, ptr->record, arg);
	    switch (retval) {
	      case ST_CHECK:	/* check if hash is modified during iteration */
		i = ptr->hash % table->num_bins;
		for (tmp = table->bins[i]; tmp != ptr; tmp = tmp->next) {
		    if (!tmp) {
			/* call func with error notice */
			retval = (*func)(0, 0, arg, 1);
			return 1;
		    }
		}
		/* fall through */
	      case ST_CONTINUE:
		ptr = ptr->fore;
		break;
	      case ST_STOP:
		return 0;
	      case ST_DELETE:
		last = &table->bins[ptr->hash % table->num_bins];
		for (; (tmp = *last) != 0; last = &tmp->next) {
		    if (ptr == tmp) {
			tmp = ptr->fore;
			*last = ptr->next;
			REMOVE_ENTRY(table, ptr);
			free(ptr);
			if (ptr == tmp) return 0;
			ptr = tmp;
			break;
		    }
		}
	    }
	} while (!end && table->head);
    }
    return 0;
}

int
st_reverse_foreach(st_table *table, int (*func)(ANYARGS), st_data_t arg)
{
    st_table_entry *ptr, **last, *tmp;
    enum st_retval retval;
    int i, end;

    if ((ptr = table->head) != 0) {
	ptr = ptr->back;
	do {
	    end = ptr == table->head;
	    retval = (*func)(ptr->key, ptr->record, arg, 0);
	    switch (retval) {
	      case ST_CHECK:	/* check if hash is modified during iteration */
		i = ptr->hash % table->num_bins;
		for (tmp = table->bins[i]; tmp != ptr; tmp = tmp->next) {
		    if (!tmp) {
			/* call func with error notice */
			retval = (*func)(0, 0, arg, 1);
			return 1;
		    }
		}
		/* fall through */
	      case ST_CONTINUE:
		ptr = ptr->back;
		break;
	      case ST_STOP:
		return 0;
	      case ST_DELETE:
		last = &table->bins[ptr->hash % table->num_bins];
		for (; (tmp = *last) != 0; last = &tmp->next) {
		    if (ptr == tmp) {
			tmp = ptr->back;
			*last = ptr->next;
			REMOVE_ENTRY(table, ptr);
			free(ptr);
			ptr = tmp;
			break;
		    }
		}
		ptr = ptr->next;
		free(tmp);
		table->num_entries--;
	    }
	} while (!end && table->head);
    }
    return 0;
}

/*
 * hash_32 - 32 bit Fowler/Noll/Vo FNV-1a hash code
 *
 * @(#) $Revision$
 * @(#) $Id$
 * @(#) $Source: /src/ruby/st.c,v $
 *
 ***
 *
 * Fowler/Noll/Vo hash
 *
 * The basis of this hash algorithm was taken from an idea sent
 * as reviewer comments to the IEEE POSIX P1003.2 committee by:
 *
 *      Phong Vo (http://www.research.att.com/info/kpv/)
 *      Glenn Fowler (http://www.research.att.com/~gsf/)
 *
 * In a subsequent ballot round:
 *
 *      Landon Curt Noll (http://www.isthe.com/chongo/)
 *
 * improved on their algorithm.  Some people tried this hash
 * and found that it worked rather well.  In an EMail message
 * to Landon, they named it the ``Fowler/Noll/Vo'' or FNV hash.
 *
 * FNV hashes are designed to be fast while maintaining a low
 * collision rate. The FNV speed allows one to quickly hash lots
 * of data while maintaining a reasonable collision rate.  See:
 *
 *      http://www.isthe.com/chongo/tech/comp/fnv/index.html
 *
 * for more details as well as other forms of the FNV hash.
 ***
 *
 * To use the recommended 32 bit FNV-1a hash, pass FNV1_32A_INIT as the
 * Fnv32_t hashval argument to fnv_32a_buf() or fnv_32a_str().
 *
 ***
 *
 * Please do not copyright this code.  This code is in the public domain.
 *
 * LANDON CURT NOLL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO
 * EVENT SHALL LANDON CURT NOLL BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
 * USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
 * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 *
 * By:
 *	chongo <Landon Curt Noll> /\oo/\
 *      http://www.isthe.com/chongo/
 *
 * Share and Enjoy!	:-)
 */

/*
 * 32 bit FNV-1 and FNV-1a non-zero initial basis
 *
 * The FNV-1 initial basis is the FNV-0 hash of the following 32 octets:
 *
 *              chongo <Landon Curt Noll> /\../\
 *
 * NOTE: The \'s above are not back-slashing escape characters.
 * They are literal ASCII  backslash 0x5c characters.
 *
 * NOTE: The FNV-1a initial basis is the same value as FNV-1 by definition.
 */
#define FNV1_32A_INIT 0x811c9dc5

/*
 * 32 bit magic FNV-1a prime
 */
#define FNV_32_PRIME 0x01000193

static int
strhash(register const char *string)
{
    register unsigned int hval = FNV1_32A_INIT;

    /*
     * FNV-1a hash each octet in the buffer
     */
    while (*string) {
	/* xor the bottom with the current octet */
	hval ^= (unsigned int)*string++;

	/* multiply by the 32 bit FNV magic prime mod 2^32 */
	hval *= FNV_32_PRIME;
    }
    return hval;
}

int
st_numcmp(long x, long y)
{
    return x != y;
}

int
st_numhash(long n)
{
    return n;
}