//----------------------------------------------------------------
//	grabber2.cpp
//
//	This is a faster version of the 'grabber1.cpp' program;
//	it uses a greatly reduced number of system-calls to our
//	'vram.c' device-driver, as recommended by many students 
//	in their answer to Question IV on Midterm II.  It takes
//	advantage of that driver's ability to return 4096 bytes
//	(1024 pixels) in a single read-operation.
//
//	programmer: ALLAN CRUSE 
//	written on: 13 MAR 2005
//----------------------------------------------------------------

#include <fcntl.h>	// for open()
#include <unistd.h>	// for read(), write(), close()

int main( void )
{
	int	src = open( "/dev/vram", O_RDONLY );
	int	dst = open( "image.dat", O_CREAT | O_WRONLY | O_TRUNC, 0666 );
	
	int	res = 1280 * 1024;
	for (int i = 0; i < res/1024; i++)
		{
		unsigned long	pel[1024];
		read( src, &pel, sizeof( pel ) );
		write( dst, &pel, sizeof( pel ) );
		}
	close( dst );
	close( src );
}