K65 Tutorial 2

/*
*	Tutorial 02 - using data
*
*
*/
 
// RAM variables
var anim = 0x80;
var tmp  = 0x81;
 
 
// "data" - declare byte data block
data raster_data {
	0
	0xD0 0xD2 0xD4 0xD6 0xD8 0xDA 0xDC
	0xDE 0xDC 0xDA 0xD8 0xD6 0xD4 0xD2 0xD0
}
 
data sine_table {
	align 256	// this guarantees block starts on address divisible by 256
 
	// this generates precomputed sine table from the formula
	for x=0..255 eval [ (sin(x/128*pi*2)*.499+.499)*178+1 ]
}
 
 
 
// "inline" - this code is inlined when it's called
inline raster_bar {
	x=15
	{
		wsync
		a=raster_data,x
		cbg=a
		x--
	}!=
	cbg=a=0
}
 
 
 
// entry point block is declared with "main"
main {
	init
	{
		sync1
		sync2
		sync3
 
		// draw top bar
		raster_bar
 
		// tmp - count total empty lines
		tmp=a=180
 
		// read sine table and wait as much scanlines
		x=anim
		y=sine_table,x
		{
			wsync
			tmp--
			y--
		}!=
 
		// draw animated bar
		raster_bar
 
		// wait remaining lines
		{
			wsync
			tmp--
		}!=
 
		// draw bottom bar
		raster_bar
 
		anim++
	} always	// loop forever
}