/* * Copyright (c) 1980, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)extra.c 8.1 (Berkeley) 5/31/93 * $FreeBSD: src/games/backgammon/backgammon/extra.c,v 1.4 1999/11/30 03:48:22 billf Exp $ * $DragonFly: src/games/backgammon/backgammon/extra.c,v 1.2 2003/06/17 04:25:22 dillon Exp $ */ #include "back.h" #ifdef DEBUG #include FILE *trace; #endif /* * dble() * Have the current player double and ask opponent to accept. */ dble () { int resp; /* response to y/n */ for (;;) { writel (" doubles."); /* indicate double */ if (cturn == -pnum) { /* see if computer accepts */ if (dblgood()) { /* guess not */ writel (" Declined.\n"); nexturn(); cturn *= -2; /* indicate loss */ return; } else { /* computer accepts */ writel (" Accepted.\n"); gvalue *= 2; /* double game value */ dlast = cturn; if (tflag) gwrite(); return; } } /* ask if player accepts */ writel (" Does "); writel (cturn == 1? color[2]: color[3]); writel (" accept?"); /* get response from yorn, * a "2" means he said "p" * for print board. */ if ((resp = yorn ('R')) == 2) { writel (" Reprint.\n"); buflush(); wrboard(); writel (*Colorptr); continue; } /* check response */ if (resp) { /* accepted */ gvalue *= 2; dlast = cturn; if (tflag) gwrite(); return; } nexturn (); /* declined */ cturn *= -2; return; } } /* * dblgood () * Returns 1 if the computer would double in this position. This * is not an exact science. The computer will decline a double that he * would have made. Accumulated judgments are kept in the variable n, * which is in "pips", i.e., the position of each man summed over all * men, with opponent's totals negative. Thus, n should have a positive * value of 7 for each move ahead, or a negative value of 7 for each one * behind. */ dblgood () { int n; /* accumulated judgment */ int OFFC = *offptr; /* no. of computer's men off */ int OFFO = *offopp; /* no. of player's men off */ #ifdef DEBUG int i; if (trace == NULL) trace = fopen ("bgtrace","w"); #endif /* get real pip value */ n = eval()*cturn; #ifdef DEBUG fputs ("\nDoubles:\nBoard: ",trace); for (i = 0; i < 26; i++) fprintf (trace," %d",board[i]); fprintf (trace,"\n\tpip = %d, ",n); #endif /* below adjusts pip value * according to position * judgments */ /* check men moving off * board */ if (OFFC > -15 || OFFO > -15) { if (OFFC < 0 && OFFO < 0) { OFFC += 15; OFFO += 15; n +=((OFFC-OFFO)*7)/2; } else if (OFFC < 0) { OFFC += 15; n -= OFFO*7/2; } else if (OFFO < 0) { OFFO += 15; n += OFFC*7/2; } if (OFFC < 8 && OFFO > 8) n -= 7; if (OFFC < 10 && OFFO > 10) n -= 7; if (OFFC < 12 && OFFO > 12) n -= 7; if (OFFO < 8 && OFFC > 8) n += 7; if (OFFO < 10 && OFFC > 10) n += 7; if (OFFO < 12 && OFFC > 12) n += 7; n += ((OFFC-OFFO)*7)/2; } #ifdef DEBUG fprintf (trace,"off = %d, ",n); #endif /* see if men are trapped */ n -= freemen(bar); n += freemen(home); n += trapped(home,-cturn); n -= trapped(bar,cturn); #ifdef DEBUG fprintf (trace,"free = %d\n",n); fprintf (trace,"\tOFFC = %d, OFFO = %d\n",OFFC,OFFO); fflush (trace); #endif /* double if 2-3 moves ahead */ if (n > 10+rnum(7)) return(1); return (0); } freemen (b) int b; { int i, inc, lim; odds(0,0,0); if (board[b] == 0) return (0); inc = (b == 0? 1: -1); lim = (b == 0? 7: 18); for (i = b+inc; i != lim; i += inc) if (board[i]*inc < -1) odds(abs(b-i),0,abs(board[b])); if (abs(board[b]) == 1) return ((36-count())/5); return (count()/5); } trapped (n,inc) int n, inc; { int i, j, k; int c, l, ct; ct = 0; l = n+7*inc; for (i = n+inc; i != l; i += inc) { odds (0,0,0); c = abs(i-l); if (board[i]*inc > 0) { for (j = c; j < 13; j++) if (board[i+inc*j]*inc < -1) { if (j < 7) odds (j,0,1); for (k = 1; k < 7 && k < j; k++) if (j-k < 7) odds (k,j-k,1); } ct += abs(board[i])*(36-count()); } } return (ct/5); } eval () { int i, j; for (j = i = 0; i < 26; i++) j += (board[i] >= 0 ? i*board[i] : (25-i)*board[i]); if (off[1] >= 0) j += 25*off[1]; else j += 25*(off[1]+15); if (off[0] >= 0) j -= 25*off[0]; else j -= 25*(off[0]+15); return (j); }