1 /* 2 * Copyright (c) 1980, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)extra.c 8.1 (Berkeley) 5/31/93 34 * $FreeBSD: src/games/backgammon/backgammon/extra.c,v 1.4 1999/11/30 03:48:22 billf Exp $ 35 * $DragonFly: src/games/backgammon/backgammon/extra.c,v 1.2 2003/06/17 04:25:22 dillon Exp $ 36 */ 37 38 #include "back.h" 39 40 #ifdef DEBUG 41 #include <stdio.h> 42 FILE *trace; 43 #endif 44 45 /* 46 * dble() 47 * Have the current player double and ask opponent to accept. 48 */ 49 50 dble () { 51 int resp; /* response to y/n */ 52 53 for (;;) { 54 writel (" doubles."); /* indicate double */ 55 56 if (cturn == -pnum) { /* see if computer accepts */ 57 if (dblgood()) { /* guess not */ 58 writel (" Declined.\n"); 59 nexturn(); 60 cturn *= -2; /* indicate loss */ 61 return; 62 } else { /* computer accepts */ 63 writel (" Accepted.\n"); 64 gvalue *= 2; /* double game value */ 65 dlast = cturn; 66 if (tflag) 67 gwrite(); 68 return; 69 } 70 } 71 72 /* ask if player accepts */ 73 writel (" Does "); 74 writel (cturn == 1? color[2]: color[3]); 75 writel (" accept?"); 76 77 /* get response from yorn, 78 * a "2" means he said "p" 79 * for print board. */ 80 if ((resp = yorn ('R')) == 2) { 81 writel (" Reprint.\n"); 82 buflush(); 83 wrboard(); 84 writel (*Colorptr); 85 continue; 86 } 87 88 /* check response */ 89 if (resp) { 90 /* accepted */ 91 gvalue *= 2; 92 dlast = cturn; 93 if (tflag) 94 gwrite(); 95 return; 96 } 97 98 nexturn (); /* declined */ 99 cturn *= -2; 100 return; 101 } 102 } 103 104 /* 105 * dblgood () 106 * Returns 1 if the computer would double in this position. This 107 * is not an exact science. The computer will decline a double that he 108 * would have made. Accumulated judgments are kept in the variable n, 109 * which is in "pips", i.e., the position of each man summed over all 110 * men, with opponent's totals negative. Thus, n should have a positive 111 * value of 7 for each move ahead, or a negative value of 7 for each one 112 * behind. 113 */ 114 115 dblgood () { 116 int n; /* accumulated judgment */ 117 int OFFC = *offptr; /* no. of computer's men off */ 118 int OFFO = *offopp; /* no. of player's men off */ 119 120 #ifdef DEBUG 121 int i; 122 if (trace == NULL) 123 trace = fopen ("bgtrace","w"); 124 #endif 125 126 /* get real pip value */ 127 n = eval()*cturn; 128 #ifdef DEBUG 129 fputs ("\nDoubles:\nBoard: ",trace); 130 for (i = 0; i < 26; i++) 131 fprintf (trace," %d",board[i]); 132 fprintf (trace,"\n\tpip = %d, ",n); 133 #endif 134 135 /* below adjusts pip value 136 * according to position 137 * judgments */ 138 139 /* check men moving off 140 * board */ 141 if (OFFC > -15 || OFFO > -15) { 142 if (OFFC < 0 && OFFO < 0) { 143 OFFC += 15; 144 OFFO += 15; 145 n +=((OFFC-OFFO)*7)/2; 146 } else if (OFFC < 0) { 147 OFFC += 15; 148 n -= OFFO*7/2; 149 } else if (OFFO < 0) { 150 OFFO += 15; 151 n += OFFC*7/2; 152 } 153 if (OFFC < 8 && OFFO > 8) 154 n -= 7; 155 if (OFFC < 10 && OFFO > 10) 156 n -= 7; 157 if (OFFC < 12 && OFFO > 12) 158 n -= 7; 159 if (OFFO < 8 && OFFC > 8) 160 n += 7; 161 if (OFFO < 10 && OFFC > 10) 162 n += 7; 163 if (OFFO < 12 && OFFC > 12) 164 n += 7; 165 n += ((OFFC-OFFO)*7)/2; 166 } 167 168 #ifdef DEBUG 169 fprintf (trace,"off = %d, ",n); 170 #endif 171 172 /* see if men are trapped */ 173 n -= freemen(bar); 174 n += freemen(home); 175 n += trapped(home,-cturn); 176 n -= trapped(bar,cturn); 177 178 #ifdef DEBUG 179 fprintf (trace,"free = %d\n",n); 180 fprintf (trace,"\tOFFC = %d, OFFO = %d\n",OFFC,OFFO); 181 fflush (trace); 182 #endif 183 184 /* double if 2-3 moves ahead */ 185 if (n > 10+rnum(7)) 186 return(1); 187 return (0); 188 } 189 190 freemen (b) 191 int b; 192 193 { 194 int i, inc, lim; 195 196 odds(0,0,0); 197 if (board[b] == 0) 198 return (0); 199 inc = (b == 0? 1: -1); 200 lim = (b == 0? 7: 18); 201 for (i = b+inc; i != lim; i += inc) 202 if (board[i]*inc < -1) 203 odds(abs(b-i),0,abs(board[b])); 204 if (abs(board[b]) == 1) 205 return ((36-count())/5); 206 return (count()/5); 207 } 208 209 trapped (n,inc) 210 int n, inc; 211 212 { 213 int i, j, k; 214 int c, l, ct; 215 216 ct = 0; 217 l = n+7*inc; 218 for (i = n+inc; i != l; i += inc) { 219 odds (0,0,0); 220 c = abs(i-l); 221 if (board[i]*inc > 0) { 222 for (j = c; j < 13; j++) 223 if (board[i+inc*j]*inc < -1) { 224 if (j < 7) 225 odds (j,0,1); 226 for (k = 1; k < 7 && k < j; k++) 227 if (j-k < 7) 228 odds (k,j-k,1); 229 } 230 ct += abs(board[i])*(36-count()); 231 } 232 } 233 return (ct/5); 234 } 235 236 eval () { 237 238 int i, j; 239 240 for (j = i = 0; i < 26; i++) 241 j += (board[i] >= 0 ? i*board[i] : (25-i)*board[i]); 242 243 if (off[1] >= 0) 244 j += 25*off[1]; 245 else 246 j += 25*(off[1]+15); 247 248 if (off[0] >= 0) 249 j -= 25*off[0]; 250 else 251 j -= 25*(off[0]+15); 252 return (j); 253 } 254