2.11BSD/src/games/backgammon/move.c
/*
* Copyright (c) 1980 Regents of the University of California.
* All rights reserved. The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*/
#ifndef lint
static char sccsid[] = "@(#)move.c 5.1 (Berkeley) 5/29/85";
#endif not lint
#include "back.h"
#ifdef DEBUG
#include <stdio.h>
FILE *trace;
static char tests[20];
#endif
struct BOARD { /* structure of game position */
int b_board[26]; /* board position */
int b_in[2]; /* men in */
int b_off[2]; /* men off */
int b_st[4], b_fn[4]; /* moves */
struct BOARD *b_next; /* forward queue pointer */
};
struct BOARD *freeq = -1;
struct BOARD *checkq = -1;
struct BOARD *bsave();
struct BOARD *nextfree();
/* these variables are values for the
* candidate move */
static int ch; /* chance of being hit */
static int op; /* computer's open men */
static int pt; /* comp's protected points */
static int em; /* farthest man back */
static int frc; /* chance to free comp's men */
static int frp; /* chance to free pl's men */
/* these values are the values for the
* move chosen (so far) */
static int chance; /* chance of being hit */
static int openmen; /* computer's open men */
static int points; /* comp's protected points */
static int endman; /* farthest man back */
static int barmen; /* men on bar */
static int menin; /* men in inner table */
static int menoff; /* men off board */
static int oldfrc; /* chance to free comp's men */
static int oldfrp; /* chance to free pl's men */
static int cp[5]; /* candidate start position */
static int cg[5]; /* candidate finish position */
static int race; /* game reduced to a race */
move (okay)
int okay; /* zero if first move */
{
register int i; /* index */
register int l; /* last man */
if (okay) {
/* see if comp should double */
if (gvalue < 64 && dlast != cturn && dblgood()) {
writel (*Colorptr);
dble(); /* double */
/* return if declined */
if (cturn != 1 && cturn != -1)
return;
}
roll();
}
race = 0;
for (i = 0; i < 26; i++) {
if (board[i] < 0)
l = i;
}
for (i = 0; i < l; i++) {
if (board[i] > 0)
break;
}
if (i == l)
race = 1;
/* print roll */
if (tflag)
curmove (cturn == -1? 18: 19,0);
writel (*Colorptr);
writel (" rolls ");
writec (D0+'0');
writec (' ');
writec (D1+'0');
/* make tty interruptable
* while thinking */
if (tflag)
cline();
fixtty (noech);
/* find out how many moves */
mvlim = movallow();
if (mvlim == 0) {
writel (" but cannot use it.\n");
nexturn();
fixtty (raw);
return;
}
/* initialize */
for (i = 0; i < 4; i++)
cp[i] = cg[i] = 0;
/* strategize */
trymove (0,0);
pickmove();
/* print move */
writel (" and moves ");
for (i = 0; i < mvlim; i++) {
if (i > 0)
writec (',');
wrint (p[i] = cp[i]);
writec ('-');
wrint (g[i] = cg[i]);
makmove (i);
}
writec ('.');
/* print blots hit */
if (tflag)
curmove (20,0);
else
writec ('\n');
for (i = 0; i < mvlim; i++)
if (h[i])
wrhit(g[i]);
/* get ready for next move */
nexturn();
if (!okay) {
buflush();
sleep (3);
}
fixtty (raw); /* no more tty interrupt */
}
trymove (mvnum,swapped)
register int mvnum; /* number of move (rel zero) */
int swapped; /* see if swapped also tested */
{
register int pos; /* position on board */
register int rval; /* value of roll */
/* if recursed through all dice
* values, compare move */
if (mvnum == mvlim) {
binsert (bsave());
return;
}
/* make sure dice in always
* same order */
if (d0 == swapped)
swap;
/* choose value for this move */
rval = dice[mvnum != 0];
/* find all legitimate moves */
for (pos = bar; pos != home; pos += cturn) {
/* fix order of dice */
if (d0 == swapped)
swap;
/* break if stuck on bar */
if (board[bar] != 0 && pos != bar)
break;
/* on to next if not occupied */
if (board[pos]*cturn <= 0)
continue;
/* set up arrays for move */
p[mvnum] = pos;
g[mvnum] = pos+rval*cturn;
if (g[mvnum]*cturn >= home) {
if (*offptr < 0)
break;
g[mvnum] = home;
}
/* try to move */
if (makmove (mvnum))
continue;
else
trymove (mvnum+1,2);
/* undo move to try another */
backone (mvnum);
}
/* swap dice and try again */
if ((!swapped) && D0 != D1)
trymove (0,1);
}
struct BOARD *
bsave () {
register int i; /* index */
struct BOARD *now; /* current position */
now = nextfree (); /* get free BOARD */
/* store position */
for (i = 0; i < 26; i++)
now->b_board[i] = board[i];
now->b_in[0] = in[0];
now->b_in[1] = in[1];
now->b_off[0] = off[0];
now->b_off[1] = off[1];
for (i = 0; i < mvlim; i++) {
now->b_st[i] = p[i];
now->b_fn[i] = g[i];
}
return (now);
}
binsert (new)
struct BOARD *new; /* item to insert */
{
register struct BOARD *p = checkq; /* queue pointer */
register int result; /* comparison result */
if (p == -1) { /* check if queue empty */
checkq = p = new;
p->b_next = -1;
return;
}
result = bcomp (new,p); /* compare to first element */
if (result < 0) { /* insert in front */
new->b_next = p;
checkq = new;
return;
}
if (result == 0) { /* duplicate entry */
mvcheck (p,new);
makefree (new);
return;
}
while (p->b_next != -1) { /* traverse queue */
result = bcomp (new,p->b_next);
if (result < 0) { /* found place */
new->b_next = p->b_next;
p->b_next = new;
return;
}
if (result == 0) { /* duplicate entry */
mvcheck (p->b_next,new);
makefree (new);
return;
}
p = p->b_next;
}
/* place at end of queue */
p->b_next = new;
new->b_next = -1;
}
bcomp (a,b)
struct BOARD *a;
struct BOARD *b;
{
register int *aloc = a->b_board; /* pointer to board a */
register int *bloc = b->b_board; /* pointer to board b */
register int i; /* index */
int result; /* comparison result */
for (i = 0; i < 26; i++) { /* compare boards */
result = cturn*(aloc[i]-bloc[i]);
if (result)
return (result); /* found inequality */
}
return (0); /* same position */
}
mvcheck (incumbent,candidate)
register struct BOARD *incumbent;
register struct BOARD *candidate;
{
register int i;
register int result;
for (i = 0; i < mvlim; i++) {
result = cturn*(candidate->b_st[i]-incumbent->b_st[i]);
if (result > 0)
return;
if (result < 0)
break;
}
if (i == mvlim)
return;
for (i = 0; i < mvlim; i++) {
incumbent->b_st[i] = candidate->b_st[i];
incumbent->b_fn[i] = candidate->b_fn[i];
}
}
makefree (dead)
struct BOARD *dead; /* dead position */
{
dead->b_next = freeq; /* add to freeq */
freeq = dead;
}
struct BOARD *
nextfree () {
struct BOARD *new;
if (freeq == -1) {
new = calloc (1,sizeof (struct BOARD));
if (new == 0) {
writel ("\nOut of memory\n");
getout();
}
new->b_next = -1;
return (new);
}
new = freeq;
freeq = freeq->b_next;
}
pickmove () {
/* current game position */
register struct BOARD *now = bsave();
register struct BOARD *next; /* next move */
#ifdef DEBUG
if (trace == NULL)
trace = fopen ("bgtrace","w");
fprintf (trace,"\nRoll: %d %d%s\n",D0,D1,race? " (race)": "");
fflush (trace);
#endif
do { /* compare moves */
bcopy (checkq);
next = checkq->b_next;
makefree (checkq);
checkq = next;
movcmp();
} while (checkq != -1);
bcopy (now);
}
bcopy (s)
register struct BOARD *s; /* game situation */
{
register int i; /* index */
for (i = 0; i < 26; i++)
board[i] = s->b_board[i];
for (i = 0; i < 2; i++) {
in[i] = s->b_in[i];
off[i] = s->b_off[i];
}
for (i = 0; i < mvlim; i++) {
p[i] = s->b_st[i];
g[i] = s->b_fn[i];
}
}
movcmp () {
register int i;
register int c;
#ifdef DEBUG
if (trace == NULL)
trace = fopen ("bgtrace","w");
#endif
odds (0,0,0);
if (!race) {
ch = op = pt = 0;
for (i = 1; i < 25; i++) {
if (board[i] == cturn)
ch = canhit (i,1);
op += abs (bar-i);
}
for (i = bar+cturn; i != home; i += cturn)
if (board[i]*cturn > 1)
pt += abs(bar-i);
frc = freemen (bar)+trapped (bar,cturn);
frp = freemen (home)+trapped (home,-cturn);
}
for (em = bar; em != home; em += cturn)
if (board[em]*cturn > 0)
break;
em = abs(home-em);
#ifdef DEBUG
fputs ("Board: ",trace);
for (i = 0; i < 26; i++)
fprintf (trace, " %d",board[i]);
if (race)
fprintf (trace,"\n\tem = %d\n",em);
else
fprintf (trace,
"\n\tch = %d, pt = %d, em = %d, frc = %d, frp = %d\n",
ch,pt,em,frc,frp);
fputs ("\tMove: ",trace);
for (i = 0; i < mvlim; i++)
fprintf (trace," %d-%d",p[i],g[i]);
fputs ("\n",trace);
fflush (trace);
strcpy (tests,"");
#endif
if ((cp[0] == 0 && cg[0] == 0) || movegood()) {
#ifdef DEBUG
fprintf (trace,"\t[%s] ... wins.\n",tests);
fflush (trace);
#endif
for (i = 0; i < mvlim; i++) {
cp[i] = p[i];
cg[i] = g[i];
}
if (!race) {
chance = ch;
openmen = op;
points = pt;
endman = em;
barmen = abs(board[home]);
oldfrc = frc;
oldfrp = frp;
}
menin = *inptr;
menoff = *offptr;
}
#ifdef DEBUG
else {
fprintf (trace,"\t[%s] ... loses.\n",tests);
fflush (trace);
}
#endif
}
movegood () {
register int n;
if (*offptr == 15)
return (1);
if (menoff == 15)
return (0);
if (race) {
#ifdef DEBUG
strcat (tests,"o");
#endif
if (*offptr-menoff)
return (*offptr > menoff);
#ifdef DEBUG
strcat (tests,"e");
#endif
if (endman-em)
return (endman > em);
#ifdef DEBUG
strcat (tests,"i");
#endif
if (menin == 15)
return (0);
if (*inptr == 15)
return (1);
#ifdef DEBUG
strcat (tests,"i");
#endif
if (*inptr-menin)
return (*inptr > menin);
return (rnum(2));
} else {
n = barmen-abs(board[home]);
#ifdef DEBUG
strcat (tests,"c");
#endif
if (abs(chance-ch)+25*n > rnum(150))
return (n? (n < 0): (ch < chance));
#ifdef DEBUG
strcat (tests,"o");
#endif
if (*offptr-menoff)
return (*offptr > menoff);
#ifdef DEBUG
strcat (tests,"o");
#endif
if (abs(openmen-op) > 7+rnum(12))
return (openmen > op);
#ifdef DEBUG
strcat (tests,"b");
#endif
if (n)
return (n < 0);
#ifdef DEBUG
strcat (tests,"e");
#endif
if (abs(endman-em) > rnum(2))
return (endman > em);
#ifdef DEBUG
strcat (tests,"f");
#endif
if (abs(frc-oldfrc) > rnum(2))
return (frc < oldfrc);
#ifdef DEBUG
strcat (tests,"p");
#endif
if (abs(n = pt-points) > rnum(4))
return (n > 0);
#ifdef DEBUG
strcat (tests,"i");
#endif
if (*inptr-menin)
return (*inptr > menin);
#ifdef DEBUG
strcat (tests,"f");
#endif
if (abs(frp-oldfrp) > rnum(2))
return (frp > oldfrp);
return (rnum(2));
}
}