// 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;
	for (u32_t i = 0; i < hash_primes[mySizeIndex]; i++)
		myTable.add(vector<hash_entry_t>());
}

int hash::add(u32_t key, void *val)
{
	u32_t hashed = hash_key(key);
	for (u32_t i = 0; i < myTable[hashed].size(); i++)
		if ( myTable[hashed][i].key == key )
			return -1;			// key exists already
	kprintf("hash.cpp: %d (slot %d) -> %d\n", key, hashed, val);
	hash_entry_t he = {key, val};
	kprintf("hash.cpp: going to add {%d, %d} to vector %d\n", he.key, he.data, hashed);
	myTable[hashed].add(he);
	kprintf("hash.cpp: finished adding %d -> %d\n",
		myTable[hashed][myTable[hashed].size()-1].key,
		myTable[hashed][myTable[hashed].size()-1].data);
	mySize++;
	if ( mySize > (hash_primes[mySizeIndex] << 1) )	// re-hash
	{
		kprintf("re-hashing\n");
		vector< vector<hash_entry_t> > oldTable = myTable;
		mySizeIndex++;
		myTable = vector< vector<hash_entry_t> >();
		for (u32_t i = 0; i < hash_primes[mySizeIndex]; i++)
			myTable.add(vector<hash_entry_t>());
		mySize = 0;
		for (u32_t i = 0; i < hash_primes[mySizeIndex - 1]; i++)
		{
			for (u32_t j = 0; j < oldTable[i].size(); j++)
			{
				add(	oldTable[i][j].key,
					oldTable[i][j].data );
			}
		}
	}
	return 0;
}

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

int hash::remove(u32_t key)
{
	u32_t hashed = hash_key(key);
	for (u32_t i = 0; i < myTable[hashed].size(); i++)
		if ( myTable[hashed][i].key == key )
		{
			myTable[hashed].remove(i);	// remove key
			mySize--;
			return 0;
		}
	return -1;
}

int hash::exists(u32_t key)
{
	u32_t hashed = hash_key(key);
	for (u32_t i = 0; i < myTable[hashed].size(); i++)
		if ( myTable[hashed][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;
}

void hash::dump()
{
	kprintf("hash table @ 0x%x : {\n", &myTable);
	for (u32_t i = 0; i < hash_primes[mySizeIndex]; i++)
	{
		kprintf("\t%d @ 0x%x (", i, &myTable[i]);
		for (u32_t j = 0; j < myTable[i].size(); j++)
			kprintf("%s%d -> %d @ 0x%x", (j ? ", " : ""),
				myTable[i][j].key,
				myTable[i][j].data,
				&myTable[i][j]);
		kprintf(")\n");
	}
	kprintf("}\n");
}