rename hyperbola-quintessence files to hq
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src/hq.c
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210
src/hq.c
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/* hyperbola-quintessence.c - hyperbola quintessence functions.
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*
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* Copyright (C) 2024 Bruno Raoult ("br")
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* Licensed under the GNU General Public License v3.0 or later.
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* Some rights reserved. See COPYING.
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*
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* You should have received a copy of the GNU General Public License along with this
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* program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
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*
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* SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
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*
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*/
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#include <stdio.h>
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#include <stdarg.h>
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#include <brlib.h>
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#include "chessdefs.h"
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#include "board.h"
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#include "bitboard.h"
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#include "hq.h"
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uchar bb_rank_attacks[64 * 8];
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/**
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* hyperbola_init() - init hyperbola quintessence attack bitboards
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*
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* See: https://www.chessprogramming.org/Kindergarten_Bitboards
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* and https://www.chessprogramming.org/Hyperbola_Quintessence
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*
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*
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* Rank attacks table:
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* bb_rank_hyperbola[512 = 9 bits], indexed by oooooofff where:
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* - O = oooooo: occupation of inner 6 bits on rank
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* - F = fff: file of sliding piece
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* The index is built as (oooooo << 3 + fff), = ((O << 3) + F), where:
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* - O = all combinations of 6 bits (loop from 0 to 64)
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* - F = all files (loop from 0 to 7)
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* To retrieve the index, given an 8 bits mask M=XooooooX, and a file F=fff,
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* we get O from M with:
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* 1) remove bits 'X' (O = M & 01111110)
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* 2) shift left result 2 more bits, as bit 0 is unused and already cleared:
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* (O <<= 2)
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*
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* TODO ? create masks excluding slider (eg. bb_diag ^ bb_sq[square]),
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* to save one operation in hyperbola_moves().
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* TODO ? replace rank attack with this idea, mapping rank to diagonal ?
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* See http://timcooijmans.blogspot.com/2014/04/
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*/
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void hyperbola_init()
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{
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/* generate rank attacks, not handled by HQ
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*/
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for (int occ = 0; occ < 64; ++occ) {
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for (int file = 0; file < 8; ++file) {
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int attacks = 0;
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//int o = mask << 1; /* skip right square */
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/* set f left attacks */
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for (int slide = file - 1; slide >= 0; --slide) {
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int b = bb_sq[slide]; /* bit to consider */
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attacks |= b; /* add to attack mask */
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if ((occ << 1) & b) /* piece on b, we stop */
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break;
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}
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/* set f right attacks */
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for (int slide = file + 1; slide < 8; ++slide) {
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int b = bb_sq[slide];
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attacks |= b;
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if ((occ << 1) & b) /* piece on b, we stop */
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//if ((o & b) == b)
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break;
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}
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bb_rank_attacks[(occ << 3) + file] = attacks;
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//if (((occ << 3) + file) == 171) {
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//char str[64], str2[64];
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//printf("mask=%x=%s file=%d att=%x=%s\n",
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// occ, bitboard_rank_sprint(str, occ), file,
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// attacks, bitboard_rank_sprint(str2, attacks));
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//}
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}
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}
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}
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/**
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* hyperbola_rank_moves() - get rank moves for a sliding piece.
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* @pieces: occupation bitboard
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* @sq: piece square
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*
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* Rank attacks are not handled by HQ, so this function uses a pre-calculated
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* rank attacks table (@bb_rank_attacks).
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*
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* @Return: bitboard of @piece available pseudo-moves.
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*/
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bitboard_t hq_rank_moves(bitboard_t occ, square_t sq)
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{
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u32 rank = sq & SQ_RANKMASK;
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u32 file = sq & SQ_FILEMASK;
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u64 o = (occ >> rank) & 0176; /* 01111110 clear bits 0 & 7 */
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//char zob[128], zob2[128];
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//printf("rank_moves: occ=%lx=%s file=%d o=%lx=%s index=%ld=%ld attack=%lx=%s\n", occ,
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// bitboard_rank_sprint(zob, occ), file, o,
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// bitboard_rank_sprint(zob, o), (o << 2) + file, (o * 4) + file,
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// (bitboard_t)bb_rank_attacks[(o << 2) + file] << rank,
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// bitboard_rank_sprint(zob2, (bitboard_t)bb_rank_attacks[(o << 2) + file] << rank));
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return ((bitboard_t)bb_rank_attacks[(o << 2) + file]) << rank;
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}
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/**
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* hyperbola_moves() - get hyperbola pseudo-moves for a sliding piece
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* @pieces: occupation bitboard
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* @sq: piece square
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* @mask: the appropriate mask (pre-calculated)
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*
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* This function can be used for files, diagonal, and anti-diagonal attacks.
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* @mask is the corresponding pre-calculated table (@bb_sqfile, @bb_sqdiag,
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* or @bb_sqanti).
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* See https://www.chessprogramming.org/Hyperbola_Quintessence for details.
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*
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* @Return: bitboard of piece available pseudo-moves.
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*/
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bitboard_t hq_moves(const bitboard_t pieces, const square_t sq,
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const bitboard_t mask)
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{
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bitboard_t o = pieces & mask;
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bitboard_t r = bswap64(o);
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square_t r_sq = FLIP_V(sq);
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return ( (o - 2 * BIT(sq) )
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^ bswap64(r - 2 * BIT(r_sq)))
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& mask;
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}
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/**
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* hyperbola_file_moves() - get file pseudo-moves for a sliding piece.
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* @pieces: occupation bitboard
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* @sq: piece square
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*
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* @Return: bitboard of piece available pseudo-moves on its file.
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*/
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bitboard_t hq_file_moves(const bitboard_t occ, const square_t sq)
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{
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return hq_moves(occ, sq, bb_sqfile[sq]);
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}
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/**
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* hyperbola_diag_moves() - get diagonal pseudo-moves for a sliding piece.
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* @pieces: occupation bitboard
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* @sq: piece square
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*
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* @Return: bitboard of piece available pseudo-moves on its diagonal.
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*/
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bitboard_t hq_diag_moves(const bitboard_t occ, const square_t sq)
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{
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return hq_moves(occ, sq, bb_sqdiag[sq]);
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}
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/**
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* hyperbola_anti_moves() - get anti-diagonal pseudo-moves for a sliding piece.
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* @pieces: occupation bitboard
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* @sq: piece square
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*
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* @Return: bitboard of piece available pseudo-moves on its anti-diagonal.
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*/
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bitboard_t hq_anti_moves(const bitboard_t occ, const square_t sq)
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{
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return hq_moves(occ, sq, bb_sqanti[sq]);
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}
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/**
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* hyperbola_bishop_moves() - get bitboard of bishop pseudo-moves
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* @occ: occupation bitboard
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* @sq: bishop square
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*
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* @Return: bitboard of bishop available pseudo-moves.
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*/
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bitboard_t hq_bishop_moves(const bitboard_t occ, const square_t sq)
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{
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return hq_diag_moves(occ, sq) | hq_anti_moves(occ, sq);
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}
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/**
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* hyperbola_rook_moves() - get bitboard of rook pseudo-moves
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* @occ: occupation bitboard
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* @sq: rook square
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*
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* @Return: bitboard of rook available pseudo-moves.
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*/
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bitboard_t hq_rook_moves(const bitboard_t occ, const square_t sq)
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{
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return hq_file_moves(occ, sq) | hq_rank_moves(occ, sq);
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}
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/**
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* hyperbola_queen_moves() - get bitboard of queen pseudo-moves
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* @occ: occupation bitboard
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* @sq: queen square
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*
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* This function is a wrapper over @hyperbola_bishop_moves() and
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* @hyperbola_rook_moves().
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*
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* @Return: bitboard of queen available pseudo-moves.
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*/
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bitboard_t hq_queen_moves(const bitboard_t occ, const square_t sq)
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{
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return hq_bishop_moves(occ, sq) | hq_rook_moves(occ, sq);
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}
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