//-------------------------------------------------------------------
//	watchtsc.cpp
//
//	This program shows how to use inline assembly language to
//	read the current value of the TimeStamp Counter register.
//
//	 compile-and-link using:  $ g++ watchtsc.cpp -o watchtsc
//
//	programmer: ALLAN CRUSE
//	written on: 30 MAR 2006
//-------------------------------------------------------------------

#include <stdio.h>		// for printf()
#include <unistd.h>		// for read()
#include <termios.h>		// for tcgetattr(), tcsetattr()

unsigned long long tsc( void ) { asm(" rdtsc "); }

int main( int argc, char **argv )
{
	// preserve the initial terminal settings
	struct termios	orig_tty;
	tcgetattr( 0, &orig_tty );

	// modify some canonical terminal settings
	struct termios	work_tty = orig_tty;
	work_tty.c_lflag &= ~ECHO;	// turn off echoing of kestrokes
	work_tty.c_lflag &= ~ICANON;	// turn off keystroke buffering
	work_tty.c_lflag &= ~ISIG;	// disable CONTROL-C termination
	work_tty.c_cc[ VTIME ] = 0;	// amount of time to await input
	work_tty.c_cc[ VMIN ] = 0;	// number of characters to await
	tcsetattr( 0, TCSAFLUSH, &work_tty );

	// display continuous flicker-free text-output 
	printf( "\e[H\e[J" );	// home the cursor and clear the screen 
	printf( "\e[12;0H" );	// move the cursor to row 12, column 0
	printf( "\e[?25l" );	// and then make the cursor disappear 
	int	done = 0;
	while ( !done )
		{
		// show the current value in the timestamp register
		unsigned long long	timestamp = tsc();
		printf( "\t\t\t TimeStamp Counter = %llu \r", timestamp );

		// set the 'done' flag as soon as any key is pressed
		int	inch = 0;
		if ( read( 0, &inch, sizeof( inch ) ) > 0 ) done = 1;
		}
	printf( "\e[23;0H" );	// move cursor to row 23, column 0
	printf( "\e[?25h\n" );	// and show the cursor again

	// restore canonical terminal settings
	tcsetattr( 0, TCSAFLUSH, &orig_tty );
}