// hash.cpp

// includes

#include "board.h"
#include "hash.h"
#include "piece.h"
#include "random.h"
#include "square.h"
#include "util.h"

// variables

uint64 Castle64[16];

// prototypes

static uint64 hash_counter_key( int piece_12, int count );

// functions

// hash_init()

void hash_init()
    {

    int i;

    for ( i = 0; i < 16; i++ )
        Castle64[i] = hash_castle_key(i);
    }

// hash_key()

uint64 hash_key( const board_t *board )
    {

    uint64 key;
    int colour;
    const sq_t *ptr;
    int sq, piece;

    ASSERT(board != NULL);

    // init

    key = 0;

    // pieces

    for ( colour = 0; colour < ColourNb; colour++ )
        {
        for ( ptr = &board->piece[colour][0]; (sq = *ptr) != SquareNone; ptr++ )
            {
            piece = board->square[sq];
            key ^= hash_piece_key(piece, sq);
            }

        for ( ptr = &board->pawn[colour][0]; (sq = *ptr) != SquareNone; ptr++ )
            {
            piece = board->square[sq];
            key ^= hash_piece_key(piece, sq);
            }
        }

    // castle flags

    key ^= hash_castle_key(board->flags);

    // en-passant square

    sq = board->ep_square;

    if( sq != SquareNone )
        key ^= hash_ep_key(sq);

    // turn

    key ^= hash_turn_key(board->turn);

    return key;
    }

// hash_pawn_key()

uint64 hash_pawn_key( const board_t *board )
    {

    uint64 key;
    int colour;
    const sq_t *ptr;
    int sq, piece;

    ASSERT(board != NULL);

    // init

    key = 0;

    // pawns

    for ( colour = 0; colour < ColourNb; colour++ )
        {
        for ( ptr = &board->pawn[colour][0]; (sq = *ptr) != SquareNone; ptr++ )
            {
            piece = board->square[sq];
            key ^= hash_piece_key(piece, sq);
            }
        }

    return key;
    }

// hash_material_key()

uint64 hash_material_key( const board_t *board )
    {

    uint64 key;
    int piece_12, count;

    ASSERT(board != NULL);

    // init

    key = 0;

    // counters

    for ( piece_12 = 0; piece_12 < 12; piece_12++ )
        {
        count = board->number[piece_12];
        key ^= hash_counter_key(piece_12, count);
        }

    return key;
    }

// hash_piece_key()

uint64 hash_piece_key( int piece, int square )
    {

    ASSERT(piece_is_ok(piece));
    ASSERT(SQUARE_IS_OK(square));

    return RANDOM_64(RandomPiece+(PIECE_TO_12(piece)^1)*64+SQUARE_TO_64(square));
    }

// hash_castle_key()

uint64 hash_castle_key( int flags )
    {

    uint64 key;
    int i;

    ASSERT((flags & ~0xF) == 0);

    key = 0;

    for ( i = 0; i < 4; i++ )
        {
        if( (flags &(1 << i)) != 0 )
            key ^= RANDOM_64(RandomCastle + i);
        }

    return key;
    }

// hash_ep_key()

uint64 hash_ep_key( int square )
    {

    ASSERT(SQUARE_IS_OK(square));

    return RANDOM_64(RandomEnPassant + SQUARE_FILE(square) - FileA);
    }

// hash_turn_key()

uint64 hash_turn_key( int colour )
    {

    ASSERT(COLOUR_IS_OK(colour));

    return (COLOUR_IS_WHITE(colour)) ? RANDOM_64(RandomTurn) : 0;
    }

// hash_counter_key()

static uint64 hash_counter_key( int piece_12, int count )
    {

    uint64 key;
    int i, index;

    ASSERT(piece_12 >= 0 && piece_12 < 12);
    ASSERT(count >= 0 && count <= 10);

    // init

    key = 0;

    // counter

    index = piece_12 * 16;

    for ( i = 0; i < count; i++ )
        key ^= RANDOM_64(index + i);

    return key;
    }

// end of hash.cpp
