NetBSD-5.0.2/games/backgammon/backgammon/extra.c
/* $NetBSD: extra.c,v 1.6 2005/07/01 01:12:39 jmc Exp $ */
/*
* 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. 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.
*/
#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)extra.c 8.1 (Berkeley) 5/31/93";
#else
__RCSID("$NetBSD: extra.c,v 1.6 2005/07/01 01:12:39 jmc Exp $");
#endif
#endif /* not lint */
#include "back.h"
#include "backlocal.h"
#ifdef DEBUG
FILE *trace;
#endif
/*
* dble()
* Have the current player double and ask opponent to accept.
*/
void
dble(void)
{
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.
*/
int
dblgood(void)
{
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);
}
int
freemen(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);
}
int
trapped(int n, int 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);
}
int
eval(void)
{
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);
}