1 /*
2 * Copyright (c) 1980, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * %sccs.include.redist.c%
6 */
7
8 #ifndef lint
9 static char sccsid[] = "@(#)extra.c 8.1 (Berkeley) 05/31/93";
10 #endif /* not lint */
11
12 #include "back.h"
13
14 #ifdef DEBUG
15 #include <stdio.h>
16 FILE *trace;
17 #endif
18
19 /*
20 * dble()
21 * Have the current player double and ask opponent to accept.
22 */
23
dble()24 dble () {
25 register int resp; /* response to y/n */
26
27 for (;;) {
28 writel (" doubles."); /* indicate double */
29
30 if (cturn == -pnum) { /* see if computer accepts */
31 if (dblgood()) { /* guess not */
32 writel (" Declined.\n");
33 nexturn();
34 cturn *= -2; /* indicate loss */
35 return;
36 } else { /* computer accepts */
37 writel (" Accepted.\n");
38 gvalue *= 2; /* double game value */
39 dlast = cturn;
40 if (tflag)
41 gwrite();
42 return;
43 }
44 }
45
46 /* ask if player accepts */
47 writel (" Does ");
48 writel (cturn == 1? color[2]: color[3]);
49 writel (" accept?");
50
51 /* get response from yorn,
52 * a "2" means he said "p"
53 * for print board. */
54 if ((resp = yorn ('R')) == 2) {
55 writel (" Reprint.\n");
56 buflush();
57 wrboard();
58 writel (*Colorptr);
59 continue;
60 }
61
62 /* check response */
63 if (resp) {
64 /* accepted */
65 gvalue *= 2;
66 dlast = cturn;
67 if (tflag)
68 gwrite();
69 return;
70 }
71
72 nexturn (); /* declined */
73 cturn *= -2;
74 return;
75 }
76 }
77
78 /*
79 * dblgood ()
80 * Returns 1 if the computer would double in this position. This
81 * is not an exact science. The computer will decline a double that he
82 * would have made. Accumulated judgments are kept in the variable n,
83 * which is in "pips", i.e., the position of each man summed over all
84 * men, with opponent's totals negative. Thus, n should have a positive
85 * value of 7 for each move ahead, or a negative value of 7 for each one
86 * behind.
87 */
88
dblgood()89 dblgood () {
90 register int n; /* accumulated judgment */
91 register int OFFC = *offptr; /* no. of computer's men off */
92 register int OFFO = *offopp; /* no. of player's men off */
93
94 #ifdef DEBUG
95 register int i;
96 if (trace == NULL)
97 trace = fopen ("bgtrace","w");
98 #endif
99
100 /* get real pip value */
101 n = eval()*cturn;
102 #ifdef DEBUG
103 fputs ("\nDoubles:\nBoard: ",trace);
104 for (i = 0; i < 26; i++)
105 fprintf (trace," %d",board[i]);
106 fprintf (trace,"\n\tpip = %d, ",n);
107 #endif
108
109 /* below adjusts pip value
110 * according to position
111 * judgments */
112
113 /* check men moving off
114 * board */
115 if (OFFC > -15 || OFFO > -15) {
116 if (OFFC < 0 && OFFO < 0) {
117 OFFC += 15;
118 OFFO += 15;
119 n +=((OFFC-OFFO)*7)/2;
120 } else if (OFFC < 0) {
121 OFFC += 15;
122 n -= OFFO*7/2;
123 } else if (OFFO < 0) {
124 OFFO += 15;
125 n += OFFC*7/2;
126 }
127 if (OFFC < 8 && OFFO > 8)
128 n -= 7;
129 if (OFFC < 10 && OFFO > 10)
130 n -= 7;
131 if (OFFC < 12 && OFFO > 12)
132 n -= 7;
133 if (OFFO < 8 && OFFC > 8)
134 n += 7;
135 if (OFFO < 10 && OFFC > 10)
136 n += 7;
137 if (OFFO < 12 && OFFC > 12)
138 n += 7;
139 n += ((OFFC-OFFO)*7)/2;
140 }
141
142 #ifdef DEBUG
143 fprintf (trace,"off = %d, ",n);
144 #endif
145
146 /* see if men are trapped */
147 n -= freemen(bar);
148 n += freemen(home);
149 n += trapped(home,-cturn);
150 n -= trapped(bar,cturn);
151
152 #ifdef DEBUG
153 fprintf (trace,"free = %d\n",n);
154 fprintf (trace,"\tOFFC = %d, OFFO = %d\n",OFFC,OFFO);
155 fflush (trace);
156 #endif
157
158 /* double if 2-3 moves ahead */
159 if (n > 10+rnum(7))
160 return(1);
161 return (0);
162 }
163
freemen(b)164 freemen (b)
165 int b;
166
167 {
168 register int i, inc, lim;
169
170 odds(0,0,0);
171 if (board[b] == 0)
172 return (0);
173 inc = (b == 0? 1: -1);
174 lim = (b == 0? 7: 18);
175 for (i = b+inc; i != lim; i += inc)
176 if (board[i]*inc < -1)
177 odds(abs(b-i),0,abs(board[b]));
178 if (abs(board[b]) == 1)
179 return ((36-count())/5);
180 return (count()/5);
181 }
182
trapped(n,inc)183 trapped (n,inc)
184 int n, inc;
185
186 {
187 register int i, j, k;
188 int c, l, ct;
189
190 ct = 0;
191 l = n+7*inc;
192 for (i = n+inc; i != l; i += inc) {
193 odds (0,0,0);
194 c = abs(i-l);
195 if (board[i]*inc > 0) {
196 for (j = c; j < 13; j++)
197 if (board[i+inc*j]*inc < -1) {
198 if (j < 7)
199 odds (j,0,1);
200 for (k = 1; k < 7 && k < j; k++)
201 if (j-k < 7)
202 odds (k,j-k,1);
203 }
204 ct += abs(board[i])*(36-count());
205 }
206 }
207 return (ct/5);
208 }
209
eval()210 eval () {
211
212 register int i, j;
213
214 for (j = i = 0; i < 26; i++)
215 j += (board[i] >= 0 ? i*board[i] : (25-i)*board[i]);
216
217 if (off[1] >= 0)
218 j += 25*off[1];
219 else
220 j += 25*(off[1]+15);
221
222 if (off[0] >= 0)
223 j -= 25*off[0];
224 else
225 j -= 25*(off[0]+15);
226 return (j);
227 }
228