handle.c

嵌入式系统基础课件

#include "libepc.h"
#include "tetris.h"
#include <stdlib.h>

#define	HIGH_WATER	5

/* ------------------------------------------------------------ */
/* Implements all the dynamics of the Tetris object.		*/
/* Returns TRUE if Tetris object placed at or above high water.	*/
/* ------------------------------------------------------------ */
BOOL HandleObject(KEYS *keys)
	{
	static DWORD32 left_right_timer = 0 ;
	static DWORD32 vertical_timer = 0 ;
	static BOOL space_down = FALSE ;
	static char color = 0x07 ;
	static int count = 0 ;
	static int rot = 0 ;
	static int row = 0 ;
	static int col = 40 ;
	int old_row, old_col, old_rot ;
	DWORD32 now = Now_Plus(0) ;

	old_row = row ;
	old_col = col ;
	old_rot = rot ;

	if (now >= vertical_timer)
		{
		row++ ;
		vertical_timer += 200 ; /* 0.20 secs */
		}
	else if (now >= left_right_timer)
		{
		if (keys->left_down)
			{
			col -= 2 ; /* 2 columns per move */
			if (col < 0) col = 0 ;
			}
		if (keys->right_down)
			{
			col += 2 ; /* 2 columns per move */
			if (col > 76) col = 76 ;
			}
		left_right_timer += 40 ; /* 0.04 secs */
		}
	else return FALSE ;

	/* Rotate once on each depression of space bar */
	if (!space_down && keys->space_down) rot = (rot + 1) % 4 ;
	space_down = keys->space_down ;

	/* Erase the object, then look for collision at new location */
	PaintObject(old_row, old_col, old_rot, FALSE, 0x00) ;
	if (Blocked(row, col, rot))
		{
		/* Blocked: Repaint at old position */
		PaintObject(old_row, old_col, old_rot, TRUE, color) ;

		if (row != old_row)
			{
			if (row < HIGH_WATER) return TRUE ;
			Tone(1000) ;
			SetCursorPosition(0,0) ;
			PutUnsigned(++count, 10, 4) ;
			row = 0 ;
			col = 4 + 2 * (random() % 37) ;
			rot = random() % 4 ;
			if (++color == 16) color = 1 ;
			}
		else
			{
			col = old_col ;
			rot = old_rot ;
			}
		}

	/* Not blocked: Repaint at new position */
	else PaintObject(row, col, rot, TRUE, color) ;
	return FALSE ;
	}