bitboards.c

#include "stdio.h"
#include "defs.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(U64 *bb) {
  U64 b = *bb ^ (*bb - 1);
  unsigned int fold = (unsigned) ((b & 0xffffffff) ^ (b >> 32));
  *bb &= (*bb - 1);
  return BitTable[(fold * 0x783a9b23) >> 26];
}

int CountBits(U64 b) {
  int r;
  for(r = 0; b; r++, b &= b - 1);
  return r;
}

void printBitBoard (U64 bb) {
	U64 shiftMe = ONE64;

	int rank = 0;
	int file = 0;
	int sq = 0;
	int sq64 = 0;

	printf("\n");
	//printing bitboard starting backwards, so to make white at bottom
	for(rank = RANK_8; rank >= RANK_1; --rank) {
		for(file = FILE_A; file <= FILE_H; ++file) {
			sq = FRtoSQ(file,rank);
			sq64 = SQ64(sq);

			if((shiftMe << sq64) & bb)
				printf("X");
			else
				printf("-");

		}
		printf("\n");
	}

	printf("\n\n");
}