From dfd030b67af4e651a73232ab15182fe669909ef1 Mon Sep 17 00:00:00 2001 From: Marco Costalba Date: Sun, 15 Jan 2012 08:24:50 +0100 Subject: [PATCH] Make init_magic() piece agnostic All the piece dependant data is passed now as function arguments so that the code is exactly the same for bishop and rook. No functional change. Signed-off-by: Marco Costalba --- src/bitboard.cpp | 69 +++++++++++++++++++++++------------------------- src/bitboard.h | 13 ++++----- 2 files changed, 40 insertions(+), 42 deletions(-) diff --git a/src/bitboard.cpp b/src/bitboard.cpp index c56d8e90..21cd34a2 100644 --- a/src/bitboard.cpp +++ b/src/bitboard.cpp @@ -59,11 +59,13 @@ namespace { CACHE_LINE_ALIGNMENT int BSFTable[64]; - Bitboard RookTable[0x19000]; // Storage space for rook attacks - Bitboard BishopTable[0x1480]; // Storage space for bishop attacks + Bitboard RTable[0x19000]; // Storage space for rook attacks + Bitboard BTable[0x1480]; // Storage space for bishop attacks - void init_magic_bitboards(PieceType pt, Bitboard* attacks[], Bitboard magics[], - Bitboard masks[], int shifts[]); + typedef unsigned (Fn)(Square, Bitboard); + + void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[], + Bitboard masks[], int shifts[], Square deltas[], Fn get_index); } @@ -220,8 +222,11 @@ void bitboards_init() { set_bit(&StepAttacksBB[make_piece(c, pt)][s], to); } - init_magic_bitboards(ROOK, RAttacks, RMagics, RMasks, RShifts); - init_magic_bitboards(BISHOP, BAttacks, BMagics, BMasks, BShifts); + Square RDeltas[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W }; + Square BDeltas[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW }; + + init_magics(RTable, RAttacks, RMagics, RMasks, RShifts, RDeltas, r_index); + init_magics(BTable, BAttacks, BMagics, BMasks, BShifts, BDeltas, b_index); for (Square s = SQ_A1; s <= SQ_H8; s++) { @@ -244,28 +249,22 @@ void bitboards_init() { namespace { - Bitboard sliding_attacks(PieceType pt, Square sq, Bitboard occupied) { + Bitboard sliding_attack(Square deltas[], Square sq, Bitboard occupied) { - Square deltas[][4] = { { DELTA_N, DELTA_E, DELTA_S, DELTA_W }, - { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW } }; - Bitboard attacks = 0; - Square* delta = (pt == ROOK ? deltas[0] : deltas[1]); + Bitboard attack = 0; for (int i = 0; i < 4; i++) - { - Square s = sq + delta[i]; - - while (square_is_ok(s) && square_distance(s, s - delta[i]) == 1) + for (Square s = sq + deltas[i]; + square_is_ok(s) && square_distance(s, s - deltas[i]) == 1; + s += deltas[i]) { - set_bit(&attacks, s); + set_bit(&attack, s); if (bit_is_set(occupied, s)) break; - - s += delta[i]; } - } - return attacks; + + return attack; } @@ -291,22 +290,22 @@ namespace { } - // init_magic_bitboards() computes all rook and bishop magics at startup. - // Magic bitboards are used to look up attacks of sliding pieces. As reference - // see chessprogramming.wikispaces.com/Magic+Bitboards. In particular, here we + // init_magics() computes all rook and bishop attacks at startup. Magic + // bitboards are used to look up attacks of sliding pieces. As a reference see + // chessprogramming.wikispaces.com/Magic+Bitboards. In particular, here we // use the so called "fancy" approach. - void init_magic_bitboards(PieceType pt, Bitboard* attacks[], Bitboard magics[], - Bitboard masks[], int shifts[]) { + void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[], + Bitboard masks[], int shifts[], Square deltas[], Fn get_index) { int MagicBoosters[][8] = { { 3191, 2184, 1310, 3618, 2091, 1308, 2452, 3996 }, { 1059, 3608, 605, 3234, 3326, 38, 2029, 3043 } }; RKISS rk; Bitboard occupancy[4096], reference[4096], edges, b; - int i, size, index, booster; + int i, size, booster; // attacks[s] is a pointer to the beginning of the attacks table for square 's' - attacks[SQ_A1] = (pt == ROOK ? RookTable : BishopTable); + attacks[SQ_A1] = table; for (Square s = SQ_A1; s <= SQ_H8; s++) { @@ -318,15 +317,15 @@ namespace { // all the attacks for each possible subset of the mask and so is 2 power // the number of 1s of the mask. Hence we deduce the size of the shift to // apply to the 64 or 32 bits word to get the index. - masks[s] = sliding_attacks(pt, s, 0) & ~edges; + masks[s] = sliding_attack(deltas, s, 0) & ~edges; shifts[s] = (Is64Bit ? 64 : 32) - popcount(masks[s]); // Use Carry-Rippler trick to enumerate all subsets of masks[s] and - // store the corresponding sliding attacks bitboard in reference[]. + // store the corresponding sliding attack bitboard in reference[]. b = size = 0; do { occupancy[size] = b; - reference[size++] = sliding_attacks(pt, s, b); + reference[size++] = sliding_attack(deltas, s, b); b = (b - masks[s]) & masks[s]; } while (b); @@ -349,14 +348,12 @@ namespace { // effect of verifying the magic. for (i = 0; i < size; i++) { - index = (pt == ROOK ? rook_index(s, occupancy[i]) - : bishop_index(s, occupancy[i])); + Bitboard& attack = attacks[s][get_index(s, occupancy[i])]; - if (!attacks[s][index]) - attacks[s][index] = reference[i]; - - else if (attacks[s][index] != reference[i]) + if (attack && attack != reference[i]) break; + + attack = reference[i]; } } while (i != size); } diff --git a/src/bitboard.h b/src/bitboard.h index 3b82e2da..94579124 100644 --- a/src/bitboard.h +++ b/src/bitboard.h @@ -140,33 +140,34 @@ inline Bitboard in_front_bb(Color c, Square s) { #if defined(IS_64BIT) -FORCE_INLINE unsigned rook_index(Square s, Bitboard occ) { +FORCE_INLINE unsigned r_index(Square s, Bitboard occ) { return unsigned(((occ & RMasks[s]) * RMagics[s]) >> RShifts[s]); } -FORCE_INLINE unsigned bishop_index(Square s, Bitboard occ) { +FORCE_INLINE unsigned b_index(Square s, Bitboard occ) { return unsigned(((occ & BMasks[s]) * BMagics[s]) >> BShifts[s]); } #else // if !defined(IS_64BIT) -FORCE_INLINE unsigned rook_index(Square s, Bitboard occ) { +FORCE_INLINE unsigned r_index(Square s, Bitboard occ) { Bitboard b = occ & RMasks[s]; return unsigned(int(b) * int(RMagics[s]) ^ int(b >> 32) * int(RMagics[s] >> 32)) >> RShifts[s]; } -FORCE_INLINE unsigned bishop_index(Square s, Bitboard occ) { +FORCE_INLINE unsigned b_index(Square s, Bitboard occ) { Bitboard b = occ & BMasks[s]; return unsigned(int(b) * int(BMagics[s]) ^ int(b >> 32) * int(BMagics[s] >> 32)) >> BShifts[s]; } + #endif inline Bitboard rook_attacks_bb(Square s, Bitboard occ) { - return RAttacks[s][rook_index(s, occ)]; + return RAttacks[s][r_index(s, occ)]; } inline Bitboard bishop_attacks_bb(Square s, Bitboard occ) { - return BAttacks[s][bishop_index(s, occ)]; + return BAttacks[s][b_index(s, occ)]; } -- 2.39.2