/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*                                                                          *
*     Trying 2 imitate Raindrop .. Rajesh _ThE gReAt                       *
*                                                                          *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
#include<stdio.h>
#include<dos.h>
#include<conio.h>
#include<math.h>
#include<string.h>
#include<ctype.h>
#include<graphics.h>
#include<stdlib.h>

/*
#define DEBUG
*/

int rand(void);		/*  Function prototype  */
void drop(char far *);  /*  Ditto 		*/

/* 	This variable is used in both the functions so it is global :) */
char far *ptr;		/* This points to first location in VDU memory */
/* 	End of this global declaration 		                       */

main()
{
	char far *new_ptr;
	int random_no;
	ptr = (char far *)0xB0008000L;	 /* First location of video memory     */
	random_no = rand()%4000;
	if(random_no%2)
	{
		random_no++;	/* Make sure that the generated no is even */
	}
	new_ptr = ptr + random_no;
	drop(new_ptr);
}

void drop(char far *new_ptr)
{
	char hold;	/* Hold the charecter pointed to by new_ptr */
	char prev;	/* Keep the previous charecter */
	long int y;
	ptr = (char far *)0xB0008000;	/* Make sure */
	hold = *new_ptr;
	y = (long int)new_ptr;
	y -= 0xB0008000L;
	y = y%160;
#ifdef DEBUG
	printf("\n%d",y);
	getch();
#endif
	
	/* Drop Alpha-Numeric Charecters only ;)      */
	if((hold >= 'a' && hold <= 'z') || (hold >= 'A' && hold <= 'Z') || (hold >= '0' && hold <='9'))
		*new_ptr = ' ';
	else
		main();
	for(;new_ptr < ((char far *)((long int)ptr+(long int)(24*160)+((long int)y*2))) &&!kbhit();new_ptr += 160)
	{
		prev = *new_ptr;
		*new_ptr = hold;
		delay(150);
		*new_ptr = prev; 	/* Restore */
	}
}