+static char sccsid[] = " extra.c 1.1 82/05/11 ";
+
+#include "back.h"
+
+#ifdef DEBUG
+#include <stdio.h>
+FILE *trace;
+#endif
+
+/*
+ * dble()
+ * Have the current player double and ask opponent to accept.
+ */
+
+dble () {
+ register 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;
+ }
+}
+\f
+/*
+ * 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 () {
+ register int n; /* accumulated judgment */
+ register int OFFC = *offptr; /* no. of computer's men off */
+ register int OFFO = *offopp; /* no. of player's men off */
+
+#ifdef DEBUG
+ register 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);
+}
+\f
+freemen (b)
+int b;
+
+{
+ register 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);
+}
+\f
+trapped (n,inc)
+int n, inc;
+
+{
+ register 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);
+}
+\f
+eval () {
+
+ register 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);
+}
projects / unix-history / commitdiff