// hash.cpp
// Author: Josh Holtrop
// Date: 08/28/05
// Modified: 08/28/05
// Implements a basic hash table (u32_t -> void*)

#define __HOS_CPP__

#include "hos_defines.h"
#include "hash.h"
#include "lang/vector.h"

extern "C"{
#include "display/kout.h"
#include "mm/vmm.h"
}

/* Hash Primes come from
 * http://planetmath.org/encyclopedia/GoodHashTablePrimes.html
 */
const u32_t hash_primes[] =
	{53, 97, 193, 389, 769, 1543, 3079, 6151, 12289, 24593, 49157, 98317,
	196613, 393241, 786433, 1572869, 3145739, 6291469, 12582917, 25165843,
	50331653, 100663319, 201326611, 402653189, 805306457, 1610612741};

hash::hash()
{
	mySizeIndex = 0;
	mySize = 0;
	myTable = new (vector<hash_entry_t *> *)[hash_primes[mySizeIndex]];
	for (u32_t i = 0; i < hash_primes[mySizeIndex]; i++)
		myTable[i] = NULL;
}

int hash::add(u32_t key, void *val)
{
	kprintf("$1$");
	u32_t hashed = hash_key(key);
	vector<hash_entry_t *> *vec = myTable[hashed];
	kprintf("$2$");
	if (!vec)
		myTable[hashed] = vec = new vector<hash_entry_t *>;
	for (u32_t i = 0; i < vec->size(); i++)
		if ( (*vec)[i]->key == key )
			return -1;			// key exists already
	kprintf("$3$");
	hash_entry_t *he = (hash_entry_t *) New(hash_entry_t);
	kprintf("(");
	for (u32_t i = 0; i < vec->size(); i++)
		kprintf("%d,", (*vec)[i]->key);
	kprintf(")");
	he->key = key;
	he->data = val;
	vec->add(he);
	mySize++;
	kprintf("*%d*\t", mySize);
	if ( mySize > (hash_primes[mySizeIndex] << 1) )	// re-hash
	{
		kprintf("*1*");
		vector<hash_entry_t *> **oldTable = myTable;
		mySizeIndex++;
		myTable = new (vector<hash_entry_t *> *)[hash_primes[mySizeIndex]];
		for (u32_t i = 0; i < hash_primes[mySizeIndex]; i++)
			myTable[i] = NULL;
		mySize = 0;
		kprintf("*2*");
		for (u32_t i = 0; i < hash_primes[mySizeIndex - 1]; i++)
		{
			if (oldTable[i])
			{
				for (u32_t j = 0; j < oldTable[i]->size(); j++)
				{
					add(	(*(oldTable[i]))[j]->key,
						(*(oldTable[i]))[j]->data );
					kfree( (*(oldTable[i]))[j] );
				}
				delete oldTable[i];
			}
		}
		kprintf("*3*");
		delete oldTable;
	}
	return 0;
}

void *hash::get(u32_t key)
{
	u32_t hashed = hash_key(key);
	vector<hash_entry_t *> *vec = myTable[hashed];
	if (!vec)
		return NULL;
	for (u32_t i = 0; i < vec->size(); i++)
		if ( (*vec)[i]->key == key )
			return (*vec)[i]->data;
	return NULL;
}

int hash::remove(u32_t key)
{
	u32_t hashed = hash_key(key);
	vector<hash_entry_t *> *vec = myTable[hashed];
	if (!vec)
		return -1;
	for (u32_t i = 0; i < vec->size(); i++)
		if ( (*vec)[i]->key == key )
		{
			kfree( (*vec)[i] );
			vec->remove(i);			// remove key
			mySize--;
			return 0;
		}
	return -1;
}

int hash::exists(u32_t key)
{
	u32_t hashed = hash_key(key);
	vector<hash_entry_t *> *vec = myTable[hashed];
	if (!vec)
		return 0;
	for (u32_t i = 0; i < vec->size(); i++)
		if ( (*vec)[i]->key == key )
			return 1;			// key exists
	return 0;
}

u32_t hash::hash_key(u32_t key)
{
	return key % hash_primes[mySizeIndex];
}

u32_t hash::size()
{
	return mySize;
}