#include <string.h>
#include <stdlib.h>
#include "TileHash.h"

static unsigned short PRIME[8] = {
    0x002, 0x065, 0x0c7, 0x133, 0x191, 0x1f3, 0x259, 0x2bd,
};

int
TileHash::hash(uint32 data)
{
    int value = 0;
    int n = 0;
    int key;

    for (int i = 0; i < 8; i ++) {
	key = data & 0xf;
	value += key * PRIME[n++];
	data >>= 4;
    }

    return value % hashSize;
}

TileHash::TileHash(void)
{
    hashSize = 263;
    tableSize = sizeof(TilePtr)*hashSize;

    table = (TilePtr*)malloc(tableSize);
    clear();
}

int
TileHash::put(uint32 *key, TilePtr data)
{
    int hashval = hash((uint32)key);

    for (int i = 0; i < hashSize/2; i++) {
	int index = (hashval + i*i)%hashSize;

	if (table[index] == 0) {
	    table[index] = data;
	    return index;
	}
    }

    return -1;
}

TilePtr
TileHash::get(uint32 *key)
{
    int hashval = hash((uint32)key);

    for (int i = 0; i < hashSize/2; i++) {
	int index = (hashval + i*i)%hashSize;
	
	if (table[index] != NULL &&
	    table[index]->texture_addr == key) {
	    return table[index];
	}
    }

    return NULL;
}

void
TileHash::clear(void)
{
    bzero(table, tableSize);
}