//----------------------------------------------------------------
//	ttyinfo.cpp
//
//	This program shows some information about how our Linux 
//	system implemented the 'struct termios' data structure.
//	We need this information in order to write our assembly
//	language version of applications (such as 'noecho.cpp') 
//	which inhibit the normal echoing of keyboard input.  In
//	particular, we must know how much memory will be needed 
//	to store an object of type 'struct termios'; and within
//	that object, we must know the location of the 'c_lflag'
//	field and which of its bits are the ECHO and the ECHONL
//	settings.  We also need to know the value for TCSANOW.      
//	
//	programmer: ALLAN CRUSE
//	written on: 18 SEP 2003
//----------------------------------------------------------------	

#include <stdio.h>
#include <termios.h>

struct termios	tty;

int main( void )
{
	printf( "\n\nSome details about objects of type " );
	printf( "\'struct termios\' under Linux \n" );

	// show the total size of a 'struct termios' object
	int	nbytes = sizeof( tty );
	printf( "\n\tsizeof( struct termios )=%d bytes: ", nbytes );
	
	// initialize our 'tty' object and display it in hex	
	tcgetattr( 0, &tty );
	unsigned int	*ttyp = (unsigned int*)&tty;
	for (int i = 0; i < nbytes/4; i++)
		{
		if ( ( i % 4 ) == 0 ) printf( "\n\t%08X: ", &ttyp[ i ] );
		printf( "%08X ", ttyp[ i ] );
		}
	printf( "\n" );
	
	// show the size, address, and value of the 'c_lflag' field
	nbytes = sizeof( tty.c_lflag );
	printf( "\n\tsizeof( c_lflag )=%d bytes ", nbytes );
	printf( "\n\t&c_lflag=%08X  ", &tty.c_lflag );
	printf( "c_lflag=%08X \n", tty.c_lflag );

	// show the values of some crucial manifest constants
	printf( "\n\tECHO = %08X ", ECHO );
	printf( " ECHONL = %08X  ", ECHONL );
	printf( " TCSANOW = %08X ", TCSANOW );
	printf( "\n\n" );
}