//-------------------------------------------------------------------
//	watchtsc.cpp
//
//	This application continually reads and displays the contents
//	of the '/dev/tsc' device special file created by our 'tsc.c'
//	device driver module.  To produce a clean and 'flicker-free'
//	display it employs the Linux implementation for the standard 
//	'curses' programming interface.   (The value being displayed 
//	is from the Pentium processor's TimeStamp Counter register.)
//
//	compile using:  $ g++ watchtsc.cpp -lncurses -o watchtsc
//
//	programmer: ALLAN CRUSE
//	written on: 03 APR 2003
//-------------------------------------------------------------------

#include <stdio.h>	// for printf(), perror() 
#include <fcntl.h>	// for open() 
#include <stdlib.h>	// for exit() 
#include <unistd.h>	// for read(), lseek(), close()
#include <curses.h>	// for initscr(), endwin(), etc.


char filename[] = "/dev/tsc";


int main( int argc, char **argv )
{
	int	fd = open( filename, O_RDONLY );
	if ( fd < 0 ) { perror( filename ); exit(1); }
	printf( "\nopened \'%s\':  fp=%d \n", filename, fd );

	initscr();
	noecho();
	cbreak();
	clear();
	refresh();	
	
	fd_set	permset;
	FD_ZERO( &permset );
	FD_SET( fd, &permset );
	FD_SET( STDIN_FILENO, &permset );
	int	ndevs = 1+fd;

	// sleep until some new data is available
	for(;;)	{
		fd_set	readset = permset;
		if ( select( ndevs, &readset, NULL, NULL, NULL ) < 0 ) break;
		
		char	inch;
		if ( FD_ISSET( STDIN_FILENO, &readset ) )
			if ( read( STDIN_FILENO, &inch, 1 ) > 0 )
				{
				if ( inch == 0x1B ) break;
				if (( inch == 'q' )||( inch == 'Q' )) break;
				}

		if ( FD_ISSET( fd, &readset ) )
			{
			unsigned long long	tsc;
			lseek( fd, 0, SEEK_SET );
			read( fd, &tsc, sizeof( tsc ) );
			mvprintw( 12, 22, " TimeStamp Counter: %lld ", tsc );
			move( 23, 0 );
			}

		refresh();
		}	
		
	endwin();
	close( fd );
}