#include "../search.h"

bitboard_t knight_moves[64] = {
  132096ULL,
  329728ULL,
  659712ULL,
  659712ULL >> 1,
  659712ULL >> 2,
  659712ULL >> 3,
  10489856ULL,
  4202496ULL,

  33816580ULL,
  84410376ULL,
  168886289ULL,
  168886289ULL >> 1,
  168886289ULL >> 2,
  168886289ULL >> 3,
  2685403152ULL,
  1075839008ULL,

  8657044482ULL,
  21609056261ULL,
  43234889994ULL,
  43234889994ULL >> 1,
  43234889994ULL >> 2,
  43234889994ULL >> 3,
  687463207072ULL,
  275414786112ULL,

  8657044482ULL >> 8,
  21609056261ULL >> 8,
  43234889994ULL >> 8,
  43234889994ULL >> (8 + 1),
  43234889994ULL >> (8 + 2),
  43234889994ULL >> (8 + 3),
  687463207072ULL >> 8,
  275414786112ULL >> 8,
  
  8657044482ULL >> 16,
  21609056261ULL >> 16,
  43234889994ULL >> 16,
  43234889994ULL >> (16 + 1),
  43234889994ULL >> (16 + 2),
  43234889994ULL >> (16 + 3),
  687463207072ULL >> 16,
  275414786112ULL >> 16,

  8657044482ULL >> 24,
  21609056261ULL >> 24,
  43234889994ULL >> 24,
  43234889994ULL >> (24 + 1),
  43234889994ULL >> (24 + 2),
  43234889994ULL >> (24 + 3),
  687463207072ULL >> 24,
  275414786112ULL >> 24,

  288234782788157440ULL,
  576469569871282176ULL,
  1224997833292120064ULL,
  1224997833292120064ULL >> 1,
  1224997833292120064ULL >> 2,
  1224997833292120064ULL >> 3,
  1152939783987658752ULL,
  2305878468463689728ULL,

  1128098930098176ULL,
  2257297371824128ULL,
  4796069720358912ULL,
  4796069720358912ULL >> 1,
  4796069720358912ULL >> 2,
  4796069720358912ULL >> 3,
  4679521487814656ULL,
  9077567998918656ULL,
};

void get_knight_moves(moves_t* moves, position_t position) {
  bitboard_t friendly_knights;
  bitboard_t friendly_pieces;
  if (position.turn == WHITE_TURN) {
    friendly_pieces = whites(position);
    friendly_knights = position.bitboards[WHITE_KNIGHT];
  } else {
    friendly_pieces = blacks(position);
    friendly_knights = position.bitboards[BLACK_KNIGHT];
  }

  while (friendly_knights) {
    int from = __builtin_ctzll(friendly_knights);
    friendly_knights &= friendly_knights - 1;
    bitboard_t ATTACK_MASK = knight_moves[from];
    ATTACK_MASK &= ~friendly_pieces;
    while (ATTACK_MASK) {
      int to = __builtin_ctzll(ATTACK_MASK);
      ATTACK_MASK &= ATTACK_MASK - 1;
      add_move(moves, from, to);
    }
  }
}