// Handel-C decade counter and seven-segment display simulation plugin

void increment_decade(unsigned 4 *count, unsigned 1 Hold);

set clock = external "Dummy";

void main (void)
{
	// Declarations
	unsigned 1 stop;
	unsigned 4 count[2];
	unsigned 1 hold;
	unsigned 8 cycles;
	unsigned 7 seg1, seg2;

	// variables must be static to be initialised
	static unsigned 7 encoder[10] = {0x01, 0x4f, 0x12, 0x06, 0x4c,
									 0x24, 0x20, 0x0f, 0x00, 0x04};

	// Plugin interfaces

	// Seven segment display 1
	interface bus_out () display1 (unsigned 7 out = seg1)
		with { extlib="7segment.dll",
			   extinst="disp1",
			   extfunc="PlugInSet" };

	// Seven segment display 2
	interface bus_out () display2 (unsigned 7 out = seg2)
		with { extlib="7segment.dll",
			   extinst="disp2",
			   extfunc="PlugInSet" };

	// Initialisation
	par {
		stop = 0;
		count[0] = 0;
		count[1] = 0;
	}

	par {

		// Cycle counter - use this to divide the clock
		while (!stop) par {
				cycles++;
			hold = (cycles != 0xff);
		}

		// Call the counter
		while (!stop)
			increment_decade(count, hold);

		// Seven segment displays
		while (!stop) par {
			seg1 = encoder[count[1]];
			seg2 = encoder[count[0]];
		}
	}
}

// This function describes a two digit BCD counter

void increment_decade(unsigned 4 *count, unsigned 1 Hold)
{
	if (Hold)
		count[0] = count[0];		/* You have to do something! */
	else if ( count[0] == 9 ) par {	/* "par" ensures one cycle */
		count[0] = 0;
		if ( count[1] == 9 )
			count[1] = 0;
		else
			count[1]++;
	} else
		count[0]++;
}