4.3BSD - /usr/src/games/backgammon/extra.c

   1: /*
   2:  * Copyright (c) 1980 Regents of the University of California.
   3:  * All rights reserved.  The Berkeley software License Agreement
   4:  * specifies the terms and conditions for redistribution.
   5:  */
   6: 
   7: #ifndef lint
   8: static char sccsid[] = "@(#)extra.c	5.1 (Berkeley) 5/29/85";
   9: #endif not lint
  10: 
  11: #include "back.h"
  12: 
  13: #ifdef DEBUG
  14: #include <stdio.h>
  15: FILE    *trace;
  16: #endif
  17: 
  18: /*
  19:  * dble()
  20:  *	Have the current player double and ask opponent to accept.
  21:  */
  22: 
  23: dble ()  {
  24:     register int    resp;           /* response to y/n */
  25: 
  26:     for (;;)  {
  27:         writel (" doubles.");       /* indicate double */
  28: 
  29:         if (cturn == -pnum)  {      /* see if computer accepts */
  30:             if (dblgood())  {       /* guess not */
  31:                 writel ("  Declined.\n");
  32:                 nexturn();
  33:                 cturn *= -2;        /* indicate loss */
  34:                 return;
  35:             } else  {           /* computer accepts */
  36:                 writel ("  Accepted.\n");
  37:                 gvalue *= 2;        /* double game value */
  38:                 dlast = cturn;
  39:                 if (tflag)
  40:                     gwrite();
  41:                 return;
  42:             }
  43:         }
  44: 
  45:                         /* ask if player accepts */
  46:         writel ("  Does ");
  47:         writel (cturn == 1? color[2]: color[3]);
  48:         writel (" accept?");
  49: 
  50:                         /* get response from yorn,
  51: 						 * a "2" means he said "p"
  52: 						 * for print board. */
  53:         if ((resp = yorn ('R')) == 2)  {
  54:             writel ("  Reprint.\n");
  55:             buflush();
  56:             wrboard();
  57:             writel (*Colorptr);
  58:             continue;
  59:         }
  60: 
  61:                         /* check response */
  62:         if (resp)  {
  63:                             /* accepted */
  64:             gvalue *= 2;
  65:             dlast = cturn;
  66:             if (tflag)
  67:                 gwrite();
  68:             return;
  69:         }
  70: 
  71:         nexturn ();         /* declined */
  72:         cturn *= -2;
  73:         return;
  74:     }
  75: }
  76: 
  77: /*
  78:  * dblgood ()
  79:  *	Returns 1 if the computer would double in this position.  This
  80:  * is not an exact science.  The computer will decline a double that he
  81:  * would have made.  Accumulated judgments are kept in the variable n,
  82:  * which is in "pips", i.e., the position of each man summed over all
  83:  * men, with opponent's totals negative.  Thus, n should have a positive
  84:  * value of 7 for each move ahead, or a negative value of 7 for each one
  85:  * behind.
  86:  */
  87: 
  88: dblgood ()  {
  89:     register int    n;          /* accumulated judgment */
  90:     register int    OFFC = *offptr;     /* no. of computer's men off */
  91:     register int    OFFO = *offopp;     /* no. of player's men off */
  92: 
  93: #ifdef DEBUG
  94:     register int    i;
  95:     if (trace == NULL)
  96:         trace = fopen ("bgtrace","w");
  97: #endif
  98: 
  99:                         /* get real pip value */
 100:     n = eval()*cturn;
 101: #ifdef DEBUG
 102:     fputs ("\nDoubles:\nBoard: ",trace);
 103:     for (i = 0; i < 26; i++)
 104:         fprintf (trace," %d",board[i]);
 105:     fprintf (trace,"\n\tpip = %d, ",n);
 106: #endif
 107: 
 108:                         /* below adjusts pip value
 109: 						 * according to position
 110: 						 * judgments */
 111: 
 112:                         /* check men moving off
 113: 						 * board */
 114:     if (OFFC > -15 || OFFO > -15)  {
 115:         if (OFFC < 0 && OFFO < 0)  {
 116:             OFFC += 15;
 117:             OFFO += 15;
 118:             n +=((OFFC-OFFO)*7)/2;
 119:         } else if (OFFC < 0)  {
 120:             OFFC += 15;
 121:             n -= OFFO*7/2;
 122:         } else if (OFFO < 0)  {
 123:             OFFO += 15;
 124:             n += OFFC*7/2;
 125:         }
 126:         if (OFFC < 8 && OFFO > 8)
 127:             n -= 7;
 128:         if (OFFC < 10 && OFFO > 10)
 129:             n -= 7;
 130:         if (OFFC < 12 && OFFO > 12)
 131:             n -= 7;
 132:         if (OFFO < 8 && OFFC > 8)
 133:             n += 7;
 134:         if (OFFO < 10 && OFFC > 10)
 135:             n += 7;
 136:         if (OFFO < 12 && OFFC > 12)
 137:             n += 7;
 138:         n += ((OFFC-OFFO)*7)/2;
 139:     }
 140: 
 141: #ifdef DEBUG
 142:     fprintf (trace,"off = %d, ",n);
 143: #endif
 144: 
 145:                         /* see if men are trapped */
 146:     n -= freemen(bar);
 147:     n += freemen(home);
 148:     n += trapped(home,-cturn);
 149:     n -= trapped(bar,cturn);
 150: 
 151: #ifdef DEBUG
 152:     fprintf (trace,"free = %d\n",n);
 153:     fprintf (trace,"\tOFFC = %d, OFFO = %d\n",OFFC,OFFO);
 154:     fflush (trace);
 155: #endif
 156: 
 157:                         /* double if 2-3 moves ahead */
 158:     if (n > 10+rnum(7))
 159:         return(1);
 160:     return (0);
 161: }
 162: 
 163: freemen (b)
 164: int b;
 165: 
 166: {
 167:     register int    i, inc, lim;
 168: 
 169:     odds(0,0,0);
 170:     if (board[b] == 0)
 171:         return (0);
 172:     inc = (b == 0? 1: -1);
 173:     lim = (b == 0? 7: 18);
 174:     for (i = b+inc; i != lim; i += inc)
 175:         if (board[i]*inc < -1)
 176:             odds(abs(b-i),0,abs(board[b]));
 177:     if (abs(board[b]) == 1)
 178:         return ((36-count())/5);
 179:     return (count()/5);
 180: }
 181: 
 182: trapped (n,inc)
 183: int n, inc;
 184: 
 185: {
 186:     register int    i, j, k;
 187:     int     c, l, ct;
 188: 
 189:     ct = 0;
 190:     l = n+7*inc;
 191:     for (i = n+inc; i != l; i += inc)  {
 192:         odds (0,0,0);
 193:         c = abs(i-l);
 194:         if (board[i]*inc > 0)  {
 195:             for (j = c; j < 13; j++)
 196:                 if (board[i+inc*j]*inc < -1)  {
 197:                     if (j < 7)
 198:                         odds (j,0,1);
 199:                     for (k = 1; k < 7 && k < j; k++)
 200:                         if (j-k < 7)
 201:                             odds (k,j-k,1);
 202:                 }
 203:             ct += abs(board[i])*(36-count());
 204:         }
 205:     }
 206:     return (ct/5);
 207: }
 208: 
 209: eval ()  {
 210: 
 211:     register int    i, j;
 212: 
 213:     for (j = i = 0; i < 26; i++)
 214:         j += (board[i] >= 0 ? i*board[i] : (25-i)*board[i]);
 215: 
 216:     if (off[1] >= 0)
 217:         j += 25*off[1];
 218:     else
 219:         j += 25*(off[1]+15);
 220: 
 221:     if (off[0] >= 0)
 222:         j -= 25*off[0];
 223:     else
 224:         j -= 25*(off[0]+15);
 225:     return (j);
 226: }

Defined functions

Defined variables