int main(void)
{
static unsigned x;
initprg();
initgame();
clrscr();
printf("Alpha test AR-Chess V 1.0\n"
"Copyright November 30, 1992\n"
"\nMr. Carey Bloodworth\n"
"\nThis program may be freely\n"
"copied and modified as long\n"
"as my name is present as the\n"
"original author.\n"
"Sharp 7xx port: A.R. Pruss");
ozdelay64hz(200);
/* ozsendscreen(); */
while (! quit)
{
if ( /* (breakpress) || */ (draw) || (mate) ||
((tomove==human) && (!bothsides)) ) inputcommand();
printboard();
/* if (pvsflag)
{
currow=7;
atright();
printf(pvsmsg);
} */
if (status[0])
{
currow=8;
atright();
printf(status);
}
currow=6;
atright();
printf(msg);
if (! (quit || mate || draw)) selectmove(tomove);
/* if (! breakpress) */ tomove=chngcolor(tomove);
};
endprg();
return 0;
}
int Board::alphabetapvs(int ply, int depth, int alpha, int beta)
{
// PV search
int i, j, movesfound, pvmovesfound, val;
triangularLength[ply] = ply;
if (depth == 0)
{
followpv = false;
return qsearch(ply, alpha, beta);
}
// repetition check:
if (repetitionCount() >= 3) return DRAWSCORE;
movesfound = 0;
pvmovesfound = 0;
moveBufLen[ply+1] = movegen(moveBufLen[ply]);
for (i = moveBufLen[ply]; i < moveBufLen[ply+1]; i++)
{
selectmove(ply, i, depth, followpv);
makeMove(moveBuffer[i]);
{
if (!isOtherKingAttacked())
{
inodes++;
movesfound++;
if (!ply) displaySearchStats(3, ply, i);
if (pvmovesfound)
{
val = -alphabetapvs(ply+1, depth-1, -alpha-1, -alpha);
if ((val > alpha) && (val < beta))
{
// in case of failure, proceed with normal alphabeta
val = -alphabetapvs(ply+1, depth - 1, -beta, -alpha);
}
}
// normal alphabeta
else val = -alphabetapvs(ply+1, depth-1, -beta, -alpha);
unmakeMove(moveBuffer[i]);
if (val >= beta)
{
// update the history heuristic
if (nextMove)
blackHeuristics[moveBuffer[i].getFrom()][moveBuffer[i].getTosq()] += depth*depth;
else
whiteHeuristics[moveBuffer[i].getFrom()][moveBuffer[i].getTosq()] += depth*depth;
return beta;
}
if (val > alpha)
{
alpha = val; // both sides want to maximize from *their* perspective
pvmovesfound++;
triangularArray[ply][ply] = moveBuffer[i]; // save this move
for (j = ply + 1; j < triangularLength[ply+1]; j++)
{
triangularArray[ply][j] = triangularArray[ply+1][j]; // and append the latest best PV from deeper plies
}
triangularLength[ply] = triangularLength[ply+1];
if (!ply)
{
msStop = timer.getms();
displaySearchStats(2, depth, val);
}
}
}
else unmakeMove(moveBuffer[i]);
}
}
// update the history heuristic
if (pvmovesfound)
{
if (nextMove)
blackHeuristics[triangularArray[ply][ply].getFrom()][triangularArray[ply][ply].getTosq()] += depth*depth;
else
whiteHeuristics[triangularArray[ply][ply].getFrom()][triangularArray[ply][ply].getTosq()] += depth*depth;
}
// 50-move rule:
if (fiftyMove >= 100) return DRAWSCORE;
// Checkmate/stalemate detection:
if (!movesfound)
{
if (isOwnKingAttacked()) return (-CHECKMATESCORE+ply-1);
else return (STALEMATESCORE);
}
return alpha;
}
int Board::alphabetapvs(int ply, int depth, int alpha, int beta)
{
// PV search
int i, j, movesfound, pvmovesfound, val;
triangularLength[ply] = ply;
if (depth <= 0)
{
followpv = false;
return qsearch(ply, alpha, beta);
}
// repetition check:
if (repetitionCount() >= 3) return DRAWSCORE;
// now try a null move to get an early beta cut-off:
if (!followpv && allownull)
{
if ((nextMove && (board.totalBlackPieces > NULLMOVE_LIMIT)) || (!nextMove && (board.totalWhitePieces > NULLMOVE_LIMIT)))
{
if (!isOwnKingAttacked())
{
allownull = false;
inodes++;
if (--countdown <=0) readClockAndInput();
nextMove = !nextMove;
hashkey ^= KEY.side;
val = -alphabetapvs(ply, depth - NULLMOVE_REDUCTION, -beta, -beta+1);
nextMove = !nextMove;
hashkey ^= KEY.side;
if (timedout) return 0;
allownull = true;
if (val >= beta) return val;
}
}
}
allownull = true;
movesfound = 0;
pvmovesfound = 0;
moveBufLen[ply+1] = movegen(moveBufLen[ply]);
for (i = moveBufLen[ply]; i < moveBufLen[ply+1]; i++)
{
selectmove(ply, i, depth, followpv);
makeMove(moveBuffer[i]);
{
if (!isOtherKingAttacked())
{
inodes++;
if (--countdown <=0) readClockAndInput();
movesfound++;
if (!ply) displaySearchStats(3, ply, i);
if (pvmovesfound)
{
val = -alphabetapvs(ply+1, depth-1, -alpha-1, -alpha);
if ((val > alpha) && (val < beta))
{
// in case of failure, proceed with normal alphabeta
val = -alphabetapvs(ply+1, depth - 1, -beta, -alpha);
}
}
// normal alphabeta
else val = -alphabetapvs(ply+1, depth-1, -beta, -alpha);
unmakeMove(moveBuffer[i]);
if (timedout) return 0;
if (val >= beta)
{
// update the history heuristic
if (nextMove)
blackHeuristics[moveBuffer[i].getFrom()][moveBuffer[i].getTosq()] += depth*depth;
else
whiteHeuristics[moveBuffer[i].getFrom()][moveBuffer[i].getTosq()] += depth*depth;
return beta;
}
if (val > alpha)
{
alpha = val; // both sides want to maximize from *their* perspective
pvmovesfound++;
triangularArray[ply][ply] = moveBuffer[i]; // save this move
for (j = ply + 1; j < triangularLength[ply+1]; j++)
{
triangularArray[ply][j] = triangularArray[ply+1][j]; // and append the latest best PV from deeper plies
}
triangularLength[ply] = triangularLength[ply+1];
if (!ply) displaySearchStats(2, depth, val);
}
}
else unmakeMove(moveBuffer[i]);
}
}
// update the history heuristic
if (pvmovesfound)
{
if (nextMove)
blackHeuristics[triangularArray[ply][ply].getFrom()][triangularArray[ply][ply].getTosq()] += depth*depth;
else
whiteHeuristics[triangularArray[ply][ply].getFrom()][triangularArray[ply][ply].getTosq()] += depth*depth;
}
// 50-move rule:
if (fiftyMove >= 100) return DRAWSCORE;
// Checkmate/stalemate detection:
if (!movesfound)
{
if (isOwnKingAttacked()) return (-CHECKMATESCORE+ply-1);
else return (STALEMATESCORE);
}
return alpha;
}
