text: /*	$OpenBSD: shapes.c,v 1.9 2010/07/20 00:15:20 deraadt Exp $	*/
  /*	$NetBSD: shapes.c,v 1.2 1995/04/22 07:42:44 cgd Exp $	*/
  
  /*-
   * Copyright (c) 1992, 1993
   *	The Regents of the University of California.  All rights reserved.
   *
   * This code is derived from software contributed to Berkeley by
   * Chris Torek and Darren F. Provine.
   *
   * 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.
   *
   *	@(#)shapes.c	8.1 (Berkeley) 5/31/93
   */
  
  /*
   * Tetris shapes and related routines.
   *
   * Note that the first 7 are `well known'.
   */
  
  #include <unistd.h>
  #include "tetris.h"
  
  #define	TL	-B_COLS-1	/* top left */
  #define	TC	-B_COLS		/* top center */
  #define	TR	-B_COLS+1	/* top right */
  #define	ML	-1		/* middle left */
  #define	MR	1		/* middle right */
  #define	BL	B_COLS-1	/* bottom left */
  #define	BC	B_COLS		/* bottom center */
  #define	BR	B_COLS+1	/* bottom right */
  
  const struct shape shapes[] = {
  	/* 0*/	{ 7,	7,	{ TL, TC, MR } },
  	/* 1*/	{ 8,	8,	{ TC, TR, ML } },
  	/* 2*/	{ 9,	11,	{ ML, MR, BC } },
  	/* 3*/	{ 3,	3,	{ TL, TC, ML } },
  	/* 4*/	{ 12,	14,	{ ML, BL, MR } },
  	/* 5*/	{ 15,	17,	{ ML, BR, MR } },
  	/* 6*/	{ 18,	18,	{ ML, MR, 2  } }, /* sticks out */
  	/* 7*/	{ 0,	0,	{ TC, ML, BL } },
  	/* 8*/	{ 1,	1,	{ TC, MR, BR } },
  	/* 9*/	{ 10,	2,	{ TC, MR, BC } },
  	/*10*/	{ 11,	9,	{ TC, ML, MR } },
  	/*11*/	{ 2,	10,	{ TC, ML, BC } },
  	/*12*/	{ 13,	4,	{ TC, BC, BR } },
  	/*13*/	{ 14,	12,	{ TR, ML, MR } },
  	/*14*/	{ 4,	13,	{ TL, TC, BC } },
  	/*15*/	{ 16,	5,	{ TR, TC, BC } },
  	/*16*/	{ 17,	15,	{ TL, MR, ML } },
  	/*17*/	{ 5,	16,	{ TC, BC, BL } },
  	/*18*/	{ 6,	6,	{ TC, BC, 2*B_COLS } }/* sticks out */
  };
  
  /*
   * Return true iff the given shape fits in the given position,
   * taking the current board into account.
   */
  int
  fits_in(const struct shape *shape, int pos)
  {
  	const int *o = shape->off;
  
  	if (board[pos] || board[pos + *o++] || board[pos + *o++] ||
  	    board[pos + *o])
  		return 0;
  	return 1;
  }
  
  /*
   * Write the given shape into the current board, turning it on
   * if `onoff' is 1, and off if `onoff' is 0.
   */
  void
  place(const struct shape *shape, int pos, int onoff)
  {
  	const int *o = shape->off;
  
  	board[pos] = onoff;
  	board[pos + *o++] = onoff;
  	board[pos + *o++] = onoff;
  	board[pos + *o] = onoff;
  }
  