gba++ clone of rust gba-console's hello_world.rs example

hello_world.cpp

#include <gba/gba.hpp>

#define EVER ;;

using namespace gba;

static auto& DISPCNT = io::display::control;
static auto& DISPSTAT = io::display::status;
static auto& IE = io::interrupt::enable_mask;
static auto& IME = io::interrupt::master_enable;
static auto& KEYINPUT = io::keypad::input;

static uint16 * const MODE_3 = reinterpret_cast<uint16 *>( 0x6000000 );

static volatile const uint32 ZERO = 0; // volatile keeps this out of ROM for DMA fill use

int main( int argc, char * argv[] ) {
	io::interrupt::vector = irq::empty_handler();

	DISPCNT.write( display::control { .mode = 3, .background_layer2 = true } );
	DISPSTAT.write( display::status { .emit_vblank = true, .emit_vcount = true, .vcount = 0 } );

	IE.write( irq::bits { .vblank = true, .vcount = true } );
	IME.write( true );

	uint8 px = video::mode_limits<3>::width() / 2;
	uint8 py = video::mode_limits<3>::height() / 2;
	auto color = color::from_rgb24( 0xff0000 );

	// Prepare DMA fill
	io::dma::channel3.source( &ZERO ).destination( MODE_3 ).words( 240 * 80 );

	for ( EVER ) {
		// Read our keys for this frame
		const auto this_frame_keys = keypad::state( KEYINPUT.read().value() );

		// Adjust game state
		px += 2 * this_frame_keys.axis_x();
		py -= 2 * this_frame_keys.axis_y();
		if ( this_frame_keys.button_l() ) {
			color = color.rotl( 5 );
		}
		if ( this_frame_keys.button_r() ) {
			color = color.rotr( 5 );
		}

		// Wait for VBlank
		bios::vblank_intr_wait();

		// Draw the new game state
		if ( px >= video::mode_limits<3>::width() || py >= video::mode_limits<3>::height() ) {
			// Out of bounds; reset screen
			io::dma::channel3.control( dma::control {
				.source = dma::src_fix,
				.long_word = true,
				.enabled = true
			} );
			// Reset position
			px = video::mode_limits<3>::width() / 2;
			py = video::mode_limits<3>::height() / 2;
		} else {
			// Draw next part of the line
			MODE_3[( py * 240 ) + px] = color.to_uint16();
			MODE_3[( py + 1 ) * 240 + px] = color.to_uint16();
			MODE_3[( py * 240 ) + px + 1] = color.to_uint16();
			MODE_3[( py + 1 ) * 240 + px + 1] = color.to_uint16();
		}

		// Wait for VDraw
		bios::intr_wait( true, irq::bits { .vcount = true } );
	}

	return 0;	
}