bitboards.c

#include "include/definitions.h"

const int bitTable[64] = {
    63, 30, 3, 32, 25, 41, 22, 33, 15, 50, 42, 13, 11, 53, 19, 34, 61, 29, 2,
    51, 21, 43, 45, 10, 18, 47, 1, 54, 9, 57, 0, 35, 62, 31, 40, 4, 49, 5, 52,
    26, 60, 6, 23, 44, 46, 27, 56, 16, 7, 39, 48, 24, 59, 14, 12, 55, 38, 28,
    58, 20, 37, 17, 36, 8 
};

int popBit(U64Int *bitBoard) {
    U64Int bit = *bitBoard ^ (*bitBoard - 1);
    unsigned int fold = (unsigned) ((bit & 0xffffffff) ^ (bit >> 32));
    *bitBoard &= (*bitBoard - 1);
    return bitTable[(fold * 0x783a9b23) >> 26];
}

int countBits(U64Int bitBoard) {
    int numOfBits;
    for(numOfBits = 0; bitBoard; numOfBits++, bitBoard &= bitBoard - 1);
    return numOfBits;
}

void printBitBoard(U64Int bitBoard) {
    U64Int shiftMe = 1ULL;
    
    int rank = 0;
    int file = 0;
    int square = 0;
    int square64 = 0;

    printf("\n");

    for(rank = RANK_8; rank >= RANK_1; rank--) {
        for(file = FILE_A; file <= FILE_H; file++) {
            square = FILE_RANK_TO_SQUARE(file, rank); // getting 120 based index
            square64 = toSQUARE64(square); // getting 64 based index

            if((shiftMe << square64) & bitBoard) {
                printf("X");
            }
            else {
                printf("-"); 
            }
        }
        printf("\n");
    }
    printf("\n\n");
}