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movegen.cpp
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/*
MIT License
Copyright(c) 2016-2017 Judd Niemann
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files(the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions :
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
#include "movegen.h"
#include "fen.h"
#include "hashtable.h"
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#ifdef _MSC_VER
#include <intrin.h>
#else
#include <x86intrin.h>
#endif
#include <cassert>
namespace juddperft {
//////////////////////////////////////
// Implementation of Class Move //
//////////////////////////////////////
Move::Move(BitBoard From/*=0*/,BitBoard To/*=0*/,uint32_t Flags/*=0*/)
{
Move::From=From;
Move::To=To;
Move::Flags=Flags;
}
bool Move::operator==(const Move& B) const
{
return (Move::From==B.From) &&
(Move::To==B.To) &&
(Move::Piece==B.Piece);
// Note Move::Flags doesn't need to be the same
// for two moves to be considered equal.
// This is because the equality test is primarily used
// to verify inputted moves against a list of legal moves
// and there is no need to go to all the trouble of setting the flags
// on both sides.
}
Move& Move::format(
BitBoard From /*=0*/,
BitBoard To /*=0*/,
uint32_t BlackToMove /*=0*/,
uint32_t Piece /*=0*/,
uint32_t Flags /*=0*/
)
{
Move::Flags=Flags;
Move::From=From;
Move::To=To;
Move::BlackToMove=BlackToMove;
Move::Piece=Piece;
return *this;
}
//////////////////////////////////////////////
// Implementation of Class ChessPosition //
//////////////////////////////////////////////
ChessPosition::ChessPosition()
{
ChessPosition::A =0;
ChessPosition::B =0;
ChessPosition::C =0;
ChessPosition::D =0;
ChessPosition::Flags=0;
ChessPosition::material = 0;
#ifdef _USE_HASH
ChessPosition::HK = 0;
#endif
}
ChessPosition& ChessPosition::setupStartPosition()
{
ChessPosition::Flags = 0;
ChessPosition::A = 0x4Aff00000000ff4A;
ChessPosition::B = 0x3C0000000000003C;
ChessPosition::C = 0xDB000000000000DB;
ChessPosition::D = 0xffff000000000000;
ChessPosition::BlackCanCastle=1;
ChessPosition::WhiteCanCastle=1;
ChessPosition::BlackCanCastleLong=1;
ChessPosition::WhiteCanCastleLong=1;
ChessPosition::BlackForfeitedCastle=0;
ChessPosition::WhiteForfeitedCastle=0;
ChessPosition::BlackForfeitedCastleLong=0;
ChessPosition::WhiteForfeitedCastleLong=0;
ChessPosition::BlackDidCastle=0;
ChessPosition::WhiteDidCastle=0;
ChessPosition::BlackDidCastleLong=0;
ChessPosition::WhiteDidCastleLong=0;
ChessPosition::MoveNumber=1;
ChessPosition::HalfMoves=0;
ChessPosition::calculateMaterial();
#ifdef _USE_HASH
ChessPosition::calculateHash();
#endif
return *this;
}
#ifdef _USE_HASH
ChessPosition & ChessPosition::calculateHash()
{
ChessPosition::HK = 0;
// Scan the squares:
for (int q = 0; q < 64; q++)
{
unsigned int piece = getPieceAtSquare(1LL<<q);
//assert(piece != 0x08);
if(piece & 0x7)
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[piece][q];
}
if (ChessPosition::BlackToMove) ChessPosition::HK ^= zobristKeys.zkBlackToMove;
if (ChessPosition::WhiteCanCastle) ChessPosition::HK ^= zobristKeys.zkWhiteCanCastle;
if (ChessPosition::WhiteCanCastleLong) ChessPosition::HK ^= zobristKeys.zkWhiteCanCastleLong;
if (ChessPosition::BlackCanCastle) ChessPosition::HK ^= zobristKeys.zkBlackCanCastle;
if (ChessPosition::BlackCanCastleLong) ChessPosition::HK ^= zobristKeys.zkBlackCanCastleLong;
return *this;
}
#endif
ChessPosition& ChessPosition::setPieceAtSquare(const unsigned int& piece /*=0*/, BitBoard square)
{
// clear the square
ChessPosition::A &= ~square;
ChessPosition::B &= ~square;
ChessPosition::C &= ~square;
ChessPosition::D &= ~square;
// 'install' the piece
if (piece & 1)
{
ChessPosition::A |= square;
}
if (piece & 2)
{
ChessPosition::B |= square;
}
if (piece & 4)
{
ChessPosition::C |= square;
}
if (piece & 8)
{
ChessPosition::D |= square;
}
ChessPosition::calculateMaterial();
#ifdef _USE_HASH
ChessPosition::calculateHash();
#endif
return *this;
}
uint32_t ChessPosition::getPieceAtSquare(const BitBoard& square) const
{
uint32_t V;
V = (ChessPosition::D & square)?8:0;
V |=(ChessPosition::C & square)?4:0;
V |=(ChessPosition::B & square)?2:0;
V |=(ChessPosition::A & square)?1:0;
return V;
}
ChessPosition& ChessPosition::calculateMaterial()
{
ChessPosition::material=0;
BitBoard M;
BitBoard V;
for(int q=0;q<64;q++)
{
M=1LL << q;
V = (ChessPosition::D & M) >> q;
V <<= 1;
V |=(ChessPosition::C & M) >> q;
V <<= 1;
V |=(ChessPosition::B & M) >> q;
V <<= 1;
V |=(ChessPosition::A & M) >> q;
switch(V)
{
case WPAWN:
material += 100;
break;
case WBISHOP:
material += 300;
break;
case WROOK:
material += 500;
break;
case WQUEEN:
material += 900;
break;
case WKNIGHT:
material += 300;
break;
case BPAWN:
material -= 100;
break;
case BBISHOP:
material -= 300;
break;
case BROOK:
material -= 500;
break;
case BQUEEN:
material -= 900;
break;
case BKNIGHT:
material -= 300;
break;
}
}
return *this;
}
ChessPosition& ChessPosition::performMove(ChessMove M)
{
BitBoard O, To;
To = 1LL << M.ToSquare;
O = ~((1LL << M.FromSquare) | To);
unsigned long nFromSquare = M.FromSquare;
unsigned long nToSquare = M.ToSquare;
// CLEAR EP SQUARES :
// clear any enpassant squares
BitBoard EnPassant=A & B & (~C);
ChessPosition::A &= ~EnPassant;
ChessPosition::B &= ~EnPassant;
ChessPosition::C &= ~EnPassant;
ChessPosition::D &= ~EnPassant;
#ifdef _USE_HASH
unsigned long nEPSquare;
nEPSquare = getSquareIndex(EnPassant);
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[WENPASSANT][nEPSquare]; // Remove EP from nEPSquare
#endif // _USE_HASH
// APPLY CASTLING MOVES:
// we use magic XOR-tricks to do the job ! :
// The following is for O-O:
//
// K..R .RK.
// A: 1000 ^ 1010 = 0010
// B: 1000 ^ 1010 = 0010
// C: 1001 ^ 1111 = 0110
// For Black:
// D: 1001 ^ 1111 = 0110
// For White:
// D &= 0xfffffffffffffff0 (ie clear colour of affected squares from K to KR)
// The following is for O-O-O:
//
// R... K... ..KR ....
// A: 0000 1000 ^ 0010 1000 (0x28) = 0010 0000
// B: 0000 1000 ^ 0010 1000 (0x28) = 0010 0000
// C: 1000 1000 ^ 1011 1000 (0xB8) = 0011 0000
// For Black:
// D: 1000 1000 ^ 1011 1000 (0xB8) = 0011 0000
// For White:
// D &= 0xffffffffffffff07 (ie clear colour of affected squares from QR to K)
if(M.Piece == BKING)
{
if(M.Castle)
{
ChessPosition::A ^= 0x0a00000000000000;
ChessPosition::B ^= 0x0a00000000000000;
ChessPosition::C ^= 0x0f00000000000000;
ChessPosition::D ^= 0x0f00000000000000;
#ifdef _USE_HASH
HK ^= zobristKeys.zkDoBlackCastle;
if (ChessPosition::BlackCanCastleLong) ChessPosition::HK ^= zobristKeys.zkBlackCanCastleLong; // conditionally flip black castling long
#endif
ChessPosition::BlackDidCastle = 1;
ChessPosition::BlackCanCastle = 0;
ChessPosition::BlackCanCastleLong = 0;
return *this;
}
else if(M.CastleLong)
{
ChessPosition::A ^= 0x2800000000000000;
ChessPosition::B ^= 0x2800000000000000;
ChessPosition::C ^= 0xb800000000000000;
ChessPosition::D ^= 0xb800000000000000;
#ifdef _USE_HASH
HK ^= zobristKeys.zkDoBlackCastleLong;
if (ChessPosition::BlackCanCastle) ChessPosition::HK ^= zobristKeys.zkBlackCanCastle; // conditionally flip black castling
#endif
ChessPosition::BlackDidCastleLong = 1;
ChessPosition::BlackCanCastle = 0;
ChessPosition::BlackCanCastleLong = 0;
return *this;
}
else
{
// ordinary king move
if (ChessPosition::BlackCanCastle || ChessPosition::BlackCanCastleLong)
{
// Black could have castled, but chose to move the King in a non-castling move
#ifdef _USE_HASH
if(ChessPosition::BlackCanCastle) ChessPosition::HK ^= zobristKeys.zkBlackCanCastle; // conditionally flip black castling
if(ChessPosition::BlackCanCastleLong) ChessPosition::HK ^= zobristKeys.zkBlackCanCastleLong; // conditionally flip black castling long
#endif
ChessPosition::BlackForfeitedCastle = 1;
ChessPosition::BlackForfeitedCastleLong = 1;
ChessPosition::BlackCanCastle = 0;
ChessPosition::BlackCanCastleLong = 0;
}
}
}
else if (M.Piece == WKING)
{
// White
if(M.Castle)
{
ChessPosition::A ^= 0x000000000000000a;
ChessPosition::B ^= 0x000000000000000a;
ChessPosition::C ^= 0x000000000000000f;
ChessPosition::D &= 0xfffffffffffffff0; // clear colour of e1,f1,g1,h1 (make white)
#ifdef _USE_HASH
HK^=zobristKeys.zkDoWhiteCastle;
if (ChessPosition::WhiteCanCastleLong) ChessPosition::HK ^= zobristKeys.zkWhiteCanCastleLong; // conditionally flip white castling long
#endif
ChessPosition::WhiteDidCastle = 1;
ChessPosition::WhiteCanCastle = 0;
ChessPosition::WhiteCanCastleLong = 0;
return *this;
}
if(M.CastleLong)
{
ChessPosition::A ^= 0x0000000000000028;
ChessPosition::B ^= 0x0000000000000028;
ChessPosition::C ^= 0x00000000000000b8;
ChessPosition::D &= 0xffffffffffffff07; // clear colour of a1,b1,c1,d1,e1 (make white)
#ifdef _USE_HASH
HK^=zobristKeys.zkDoWhiteCastleLong;
if (ChessPosition::WhiteCanCastle) ChessPosition::HK ^= zobristKeys.zkWhiteCanCastle; // conditionally flip white castling
#endif
ChessPosition::WhiteDidCastleLong = 1;
ChessPosition::WhiteCanCastle = 0;
ChessPosition::WhiteCanCastleLong=0;
return *this;
}
else
{
// ordinary king move
if (ChessPosition::WhiteCanCastle) {
#ifdef _USE_HASH
ChessPosition::HK ^= zobristKeys.zkWhiteCanCastle; // flip white castling
#endif
ChessPosition::WhiteForfeitedCastle = 1;
ChessPosition::WhiteCanCastle = 0;
}
if (ChessPosition::WhiteCanCastleLong) {
#ifdef _USE_HASH
ChessPosition::HK ^= zobristKeys.zkWhiteCanCastleLong; // flip white castling long
#endif
ChessPosition::WhiteForfeitedCastleLong = 1;
ChessPosition::WhiteCanCastleLong = 0;
}
}
}
// LOOK FOR FORFEITED CASTLING RIGHTS DUE to ROOK MOVES:
else if(M.Piece == BROOK)
{
// if((1LL<<nFromSquare) & BLACKKRPOS)
if(nFromSquare==56)
{
// Black moved K-side Rook and forfeits right to castle K-side
if(ChessPosition::BlackCanCastle){
ChessPosition::BlackForfeitedCastle=1;
#ifdef _USE_HASH
ChessPosition::HK ^= zobristKeys.zkBlackCanCastle; // flip black castling
#endif
ChessPosition::BlackCanCastle=0;
}
}
//else if ((1LL<<nFromSquare) & BLACKQRPOS)
else if (nFromSquare==63)
{
// Black moved the QS Rook and forfeits right to castle Q-side
if (ChessPosition::BlackCanCastleLong) {
ChessPosition::BlackForfeitedCastleLong = 1;
#ifdef _USE_HASH
ChessPosition::HK ^= zobristKeys.zkBlackCanCastleLong; // flip black castling long
#endif
ChessPosition::BlackCanCastleLong=0;
}
}
}
else if(M.Piece == WROOK)
{
//if((1LL<<nFromSquare) & WHITEKRPOS)
if (nFromSquare==0)
{
// White moved K-side Rook and forfeits right to castle K-side
if (ChessPosition::WhiteCanCastle) {
ChessPosition::WhiteForfeitedCastle = 1;
#ifdef _USE_HASH
ChessPosition::HK ^= zobristKeys.zkWhiteCanCastle; // flip white castling BROKEN !!!
#endif
ChessPosition::WhiteCanCastle=0;
}
}
// else if((1LL<<nFromSquare) & WHITEQRPOS)
else if (nFromSquare==7)
{
// White moved the QSide Rook and forfeits right to castle Q-side
if (ChessPosition::WhiteCanCastleLong) {
ChessPosition::WhiteForfeitedCastleLong = 1;
#ifdef _USE_HASH
ChessPosition::HK ^= zobristKeys.zkWhiteCanCastleLong; // flip white castling long
#endif
ChessPosition::WhiteCanCastleLong=0;
}
}
}
// Ordinary Captures ////
if (M.Capture)
{
int capturedpiece;
#if defined (_WIN64) && defined (_USE_BITTEST_INSTRUCTION)
const long long d = ChessPosition::D;
const long long c = ChessPosition::C;
const long long b = ChessPosition::B;
const long long a = ChessPosition::A;
// using BitTest Intrinsic:
capturedpiece = _bittest64(&d, nToSquare) << 3
| _bittest64(&c, nToSquare) << 2
| _bittest64(&b, nToSquare) << 1
| _bittest64(&a, nToSquare);
#else
// find out which piece has been captured:
// Branchy version (reliable, maybe a tiny bit slower):
//capturedpiece = (ChessPosition::D & (1LL<<nToSquare))?8:0;
//capturedpiece |=(ChessPosition::C & (1LL<<nToSquare))?4:0;
//capturedpiece |=(ChessPosition::B & (1LL<<nToSquare))?2:0;
//capturedpiece |=(ChessPosition::A & (1LL<<nToSquare))?1:0;
// Branchless version:
capturedpiece = ((ChessPosition::D & To) >> nToSquare) << 3
| ((ChessPosition::C & To) >> nToSquare) << 2
| ((ChessPosition::B & To) >> nToSquare) << 1
| ((ChessPosition::A & To) >> nToSquare);
#endif
#ifdef _USE_HASH
// Update Hash
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[capturedpiece][nToSquare]; // Remove captured Piece
#endif
}
// Render "ordinary" moves:
ChessPosition::A &= O;
ChessPosition::B &= O;
ChessPosition::C &= O;
ChessPosition::D &= O;
// Populate new square (Branchless method):
ChessPosition::A |= static_cast<int64_t>(M.Piece & 1) << M.ToSquare;
ChessPosition::B |= static_cast<int64_t>((M.Piece & 2) >> 1) << M.ToSquare;
ChessPosition::C |= static_cast<int64_t>((M.Piece & 4) >> 2) << M.ToSquare;
ChessPosition::D |= static_cast<int64_t>((M.Piece & 8) >> 3) << M.ToSquare;
// Populate new square (Branchy):
//if (M.Piece & 1)
// ChessPosition::A |= To;
//if (M.Piece & 2)
// ChessPosition::B |= To;
//if (M.Piece & 4)
// ChessPosition::C |= To;
//if (M.Piece & 8)
// ChessPosition::D |= To;
//// Populate new square (Branchless method, BitBoard input):
//ChessPosition::A |= To & -( static_cast<int64_t>(M.Piece) & 1);
//ChessPosition::B |= To & -((static_cast<int64_t>(M.Piece) & 2) >> 1);
//ChessPosition::C |= To & -((static_cast<int64_t>(M.Piece) & 4) >> 2);
//ChessPosition::D |= To & -((static_cast<int64_t>(M.Piece) & 8) >> 3);
#ifdef _USE_HASH
// Update Hash
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[M.Piece][nFromSquare]; // Remove piece at From square
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[M.Piece][nToSquare]; // Place piece at To Square
#endif
// Promotions - Change the piece:
if (M.PromoteBishop)
{
ChessPosition::A &= ~To;
ChessPosition::B |= To;
#ifdef _USE_HASH
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[M.BlackToMove ? BPAWN : WPAWN][nToSquare]; // Remove pawn at To square
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[M.BlackToMove ? BBISHOP : WBISHOP][nToSquare]; // place Bishop at To square
#endif
M.Piece = M.BlackToMove ? BBISHOP : WBISHOP;
//
return *this;
}
else if (M.PromoteKnight)
{
ChessPosition::C |= To;
#ifdef _USE_HASH
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[M.BlackToMove ? BPAWN : WPAWN][nToSquare]; // Remove pawn at To square
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[M.BlackToMove ? BKNIGHT : WKNIGHT][nToSquare];// place Knight at To square
#endif
M.Piece = M.BlackToMove ? BKNIGHT : WKNIGHT;
//
return *this;
}
else if (M.PromoteRook)
{
ChessPosition::A &= ~To;
ChessPosition::C |= To;
#ifdef _USE_HASH
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[M.BlackToMove ? BPAWN : WPAWN][nToSquare]; // Remove pawn at To square
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[M.BlackToMove ? BROOK : WROOK][nToSquare]; // place Rook at To square
#endif
M.Piece = M.BlackToMove ? BROOK : WROOK;
//
return *this;
}
else if (M.PromoteQueen)
{
ChessPosition::A &= ~To;
ChessPosition::B |= To;
ChessPosition::C |= To;
#ifdef _USE_HASH
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[M.BlackToMove ? BPAWN : WPAWN][nToSquare]; // Remove pawn at To square
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[M.BlackToMove ? BQUEEN : WQUEEN][nToSquare]; // place Queen at To square
#endif
M.Piece = M.BlackToMove ? BQUEEN : WQUEEN;
//
return *this;
}
// For Double-Pawn Moves, set EP square: ////
else if(M.DoublePawnMove)
{
// Set EnPassant Square
if(M.BlackToMove)
{
To <<= 8;
ChessPosition::A |= To;
ChessPosition::B |= To;
ChessPosition::C &= ~To;
ChessPosition::D |= To;
#ifdef _USE_HASH
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[BENPASSANT][nToSquare + 8]; // Place Black EP at (To+8)
#endif
}
else
{
To >>= 8;
ChessPosition::A |= To;
ChessPosition::B |= To;
ChessPosition::C &= ~To;
ChessPosition::D &= ~To;
#ifdef _USE_HASH
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[WENPASSANT][nToSquare - 8]; // Place White EP at (To-8)
#endif
}
//
return *this;
}
// En-Passant Captures ////
else if(M.EnPassantCapture)
{
// remove the actual pawn (it is different to the capture square)
if(M.BlackToMove)
{
To <<= 8;
ChessPosition::A &= ~To; // clear the pawn's square
ChessPosition::B &= ~To;
ChessPosition::C &= ~To;
ChessPosition::D &= ~To;
// ChessPosition::material -= 100; // perft doesn't care
#ifdef _USE_HASH
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[WPAWN][nToSquare + 8]; // Remove WHITE Pawn at (To+8)
#endif
}
else
{
To >>= 8;
ChessPosition::A &= ~To;
ChessPosition::B &= ~To;
ChessPosition::C &= ~To;
ChessPosition::D &= ~To;
// ChessPosition::material += 100; // perft doesn't care
#ifdef _USE_HASH
ChessPosition::HK ^= zobristKeys.zkPieceOnSquare[BPAWN][nToSquare - 8]; // Remove BLACK Pawn at (To-8)
#endif
}
}
//
return *this;
}
void ChessPosition::switchSides()
{
ChessPosition::BlackToMove ^= 1;
#ifdef _USE_HASH
ChessPosition::HK ^= zobristKeys.zkBlackToMove;
#endif
return;
}
void ChessPosition::clear(void)
{
A=B=C=D=0;
Flags=0;
material = 0;
#ifdef _USE_HASH
HK = 0;
#endif
}
////////////////////////////////////////////
// Move Generation Functions
// generateMoves()
////////////////////////////////////////////
void generateMoves(const ChessPosition& P, ChessMove* pM)
{
assert((~(P.A | P.B | P.C) & P.D)==0); // Should not be any "black" empty squares
if(P.BlackToMove)
{
genBlackMoves(P,pM);
}
else
{
genWhiteMoves(P,pM);
}
}
//////////////////////////////////////////
// White Move Generation Functions: //
// genWhiteMoves(), //
// addWhiteMoveToListIfLegal(), //
// genBlackAttacks() //
//////////////////////////////////////////
void genWhiteMoves(const ChessPosition& P, ChessMove* pM)
{
ChessMove* pFirstMove = pM;
BitBoard Occupied = P.A | P.B | P.C; // all squares occupied by something
BitBoard WhiteOccupied = (Occupied & ~P.D) & ~(P.A & P.B & ~P.C); // all squares occupied by W, excluding EP Squares
BitBoard BlackOccupied = Occupied & P.D; // all squares occupied by B, including Black EP Squares
BitBoard WhiteFree; // all squares where W is free to move
WhiteFree = (P.A & P.B & ~P.C) // any EP square
| ~(Occupied) // any vacant square
| (~P.A & P.D) // Black Bishop, Rook or Queen
| (~P.B & P.D); // Black Pawn or Knight
assert(WhiteOccupied != 0);
BitBoard Square;
BitBoard CurrentSquare;
BitBoard A,B,C;
Move M; // Dummy Move object used for setting flags.
uint32_t piece=0;
unsigned long a = 63;
unsigned long b = 0;
#if defined(_USE_BITSCAN_INSTRUCTIONS) && defined(_WIN64)
// perform Bitscans to determine start and finish squares;
// Important: a and b must be initialised first !
_BitScanReverse64(&a, WhiteOccupied);
_BitScanForward64(&b, WhiteOccupied);
#else
// (just scan all 64 squares: 0-63):
#endif
for (unsigned int q=b; q<=a; q++)
{
CurrentSquare = 1LL << q;
if ((WhiteOccupied & CurrentSquare) == 0)
continue; // square empty - nothing to do
//
A = P.A & CurrentSquare;
B = P.B & CurrentSquare;
C = P.C & CurrentSquare;
if (A !=0)
{
if (B == 0)
{
if (C == 0)
{
piece=WPAWN;
// single move forward
Square = MoveUp[q] & WhiteFree & ~BlackOccupied /* pawns can't capture in forward moves */;
if((Square & RANK8) != 0)
addWhitePromotionsToListIfLegal(P, pM, q, Square, piece);
else
{
// Ordinary Pawn Advance
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
/* double move forward (only available from 2nd Rank */
if ((CurrentSquare & RANK2)!=0)
{
Square = moveUpSingleOccluded(Square,WhiteFree) & ~BlackOccupied;
M.ClearFlags();
M.DoublePawnMove=1; // this flag will cause ChessPosition::performMove() to set an ep square in the position
addWhiteMoveToListIfLegal(P,pM,q,Square,piece,M.Flags);
}
}
// generate Pawn Captures:
Square=MoveUpLeft[q] & WhiteFree & BlackOccupied;
if((Square & RANK8) != 0)
addWhitePromotionsToListIfLegal(P, pM, q, Square, piece);
else
{
// Ordinary Pawn Capture to Left
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
}
Square = MoveUpRight[q] & WhiteFree & BlackOccupied;
if((Square & RANK8) != 0)
addWhitePromotionsToListIfLegal(P, pM, q, Square, piece);
else
{
// Ordinary Pawn Capture to right
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
}
continue;
}
else
{
piece = WKNIGHT;
Square=MoveKnight8[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
Square=MoveKnight7[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
Square=MoveKnight1[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
Square=MoveKnight2[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
Square=MoveKnight3[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
Square=MoveKnight4[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
Square=MoveKnight5[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
Square=MoveKnight6[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
continue;
}
} // Ends if (B == 0)
else /* B != 0 */
{
if (C != 0)
{
piece = WKING;
Square=MoveUp[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
Square=MoveRight[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
// Conditionally generate O-O move:
if ((P.WhiteCanCastle) && // White still has castle rights AND
(CurrentSquare==WHITEKINGPOS) && // King is in correct Position AND
((~P.A & ~P.B & P.C & ~P.D & WHITEKRPOS) != 0) && // KRook is in correct Position AND
(pM->IllegalMove == 0) && // Last generated move (1 step to right) was legal AND
(WHITECASTLEZONE & Occupied) == 0 && // Castle Zone (f1,g1) is clear AND
!isWhiteInCheck(P) // King is not in Check
)
{
// OK to Castle
Square = G1; // Move King to g1
M.ClearFlags();
M.Castle=1;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece,M.Flags);
}
Square=MoveDown[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
Square=MoveLeft[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
// Conditionally generate O-O-O move:
if((P.WhiteCanCastleLong) && // White still has castle-long rights AND
(CurrentSquare==WHITEKINGPOS) && // King is in correct Position AND
((~P.A & ~P.B & P.C & ~P.D & WHITEQRPOS) != 0) && // QRook is in correct Position AND
(pM->IllegalMove == 0) && // Last generated move (1 step to left) was legal AND
(WHITECASTLELONGZONE & Occupied) == 0 && // Castle Long Zone (b1,c1,d1) is clear AND
!isWhiteInCheck(P) // King is not in Check
)
{
// Ok to Castle Long
Square = C1; // Move King to c1
M.ClearFlags();
M.CastleLong=1;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece,M.Flags);
}
Square=MoveUpRight[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
Square=MoveDownRight[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
Square=MoveDownLeft[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
Square=MoveUpLeft[q] & WhiteFree;
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
continue;
} // ENDS if (C != 0)
else
{
// en passant square - no action to be taken, but continue loop
continue;
}
} // Ends else
} // ENDS if (A !=0)
BitBoard SolidBlackPiece=P.D & ~(P.A & P.B); // All black pieces except enpassants and black king
if (B != 0)
{
// Piece can do diagonal moves (it's either a B or Q)
piece=(C == 0)? WBISHOP : WQUEEN;
Square=CurrentSquare;
do{ /* Diagonal UpRight */
Square=moveUpRightSingleOccluded(Square,WhiteFree);
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
} while (Square & ~SolidBlackPiece);
Square=CurrentSquare;
do{ /* Diagonal DownRight */
Square=moveDownRightSingleOccluded(Square,WhiteFree);
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
} while (Square & ~SolidBlackPiece);
Square=CurrentSquare;
do{ /* Diagonal DownLeft */
Square=moveDownLeftSingleOccluded(Square,WhiteFree);
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
} while (Square & ~SolidBlackPiece);
Square=CurrentSquare;
do{ /* Diagonal UpLeft */
Square=moveUpLeftSingleOccluded(Square,WhiteFree);
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
} while (Square & ~SolidBlackPiece);
}
if (C != 0)
{
// Piece can do straight moves (it's either a R or Q)
piece=( B == 0)? WROOK : WQUEEN;
Square=CurrentSquare;
do{ /* Up */
Square=moveUpSingleOccluded(Square,WhiteFree);
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
} while (Square & ~SolidBlackPiece);
Square=CurrentSquare;
do{ /* Right */
Square=moveRightSingleOccluded(Square,WhiteFree);
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
} while (Square & ~SolidBlackPiece);
Square=CurrentSquare;
do{ /*Down */
Square=moveDownSingleOccluded(Square,WhiteFree);
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
} while (Square & ~SolidBlackPiece);
Square=CurrentSquare;
do{ /*Left*/
Square=moveLeftSingleOccluded(Square,WhiteFree);
addWhiteMoveToListIfLegal(P,pM,q,Square,piece);
} while (Square & ~SolidBlackPiece);
}
} // ends loop over q;
// Hack to stuff the Move Count into the first Move:
pFirstMove->MoveCount = pM - pFirstMove;
// Create 'no more moves' move to mark end of list:
pM->FromSquare=0;
pM->ToSquare=0;
pM->Piece=0;
pM->NoMoreMoves=1;
}
inline void addWhiteMoveToListIfLegal(const ChessPosition& P, ChessMove*& pM, unsigned char fromsquare, BitBoard to, int32_t piece, int32_t flags)
{
if (to != 0)
{
ChessPosition Q = P;
pM->FromSquare = fromsquare;
pM->ToSquare = static_cast<unsigned char>(getSquareIndex(to));
assert((1LL << pM->ToSquare) == to);
pM->Flags = flags;
pM->Piece = piece;
BitBoard O = ~((1LL << fromsquare) | to);
if (pM->Castle)
{
Q.A ^= 0x000000000000000a;
Q.B ^= 0x000000000000000a;
Q.C ^= 0x000000000000000f;
// Q.D &= 0xfffffffffffffff0; // clear colour of e1,f1,g1,h1 (make white)
}
else if (pM->CastleLong)
{
Q.A ^= 0x0000000000000028;
Q.B ^= 0x0000000000000028;
Q.C ^= 0x00000000000000b8;
// Q.D &= 0xffffffffffffff07; // clear colour of a1,b1,c1,d1,e1 (make white)
}
else {
// clear old and new square:
Q.A &= O;
Q.B &= O;
Q.C &= O;
Q.D &= O;
// Populate new square (Branchless method):
Q.A |= static_cast<int64_t>(piece & 1) << pM->ToSquare;
Q.B |= static_cast<int64_t>((piece & 2) >> 1) << pM->ToSquare;
Q.C |= static_cast<int64_t>((piece & 4) >> 2) << pM->ToSquare;
Q.D |= static_cast<int64_t>((piece & 8) >> 3) << pM->ToSquare;
// Test for capture:
BitBoard PAB = (P.A & P.B); // Bitboard containing EnPassants and kings:
if (to & P.D) {
if (to & ~PAB) // Only considered a capture if dest is not an enpassant or king.
pM->Capture = 1;
else if ((piece == WPAWN) && (to & P.D & PAB & ~P.C)) {
pM->EnPassantCapture = 1;
// remove the actual pawn (as well as the ep square)
to >>= 8;
Q.A &= ~to;