CLK/OSBindings/Mac/Clock SignalTests/OPLTests.mm

//
//  OPLTests.m
//  Clock SignalTests
//
//  Created by Thomas Harte on 14/04/2020.
//  Copyright © 2020 Thomas Harte. All rights reserved.
//

#import <XCTest/XCTest.h>

#include "Tables.hpp"

#include <cmath>

@interface OPLTests: XCTestCase
@end

@implementation OPLTests

// MARK: - Table tests

- (void)testSineLookup {
	for(int c = 0; c < 1024; ++c) {
		const auto logSin = Yamaha::OPL::negative_log_sin(c);
		const auto level = Yamaha::OPL::power_two(logSin);

		double fl_angle = double(c) * M_PI / 512.0;
		double fl_level = sin(fl_angle);

		XCTAssertLessThanOrEqual(fabs(fl_level - double(level) / 4096.0), 0.01, "Sine varies by more than 0.01 at angle %d", c);
	}
}

// MARK: - Two-operator FM tests

/*- (void)compareFMTo:(NSArray *)knownGood atAttenuation:(int)attenuation {
	Yamaha::OPL::Operator modulator, carrier;
	Yamaha::OPL::Channel channel;
	Yamaha::OPL::LowFrequencyOscillator oscillator;

	// Set: AM = 0, PM = 0, EG = 1, KR = 0, MUL = 0
	modulator.set_am_vibrato_hold_sustain_ksr_multiple(0x20);
	carrier.set_am_vibrato_hold_sustain_ksr_multiple(0x20);

	// Set: KL = 0, TL = 0
	modulator.set_scaling_output(attenuation);
	carrier.set_scaling_output(0);

	// Set: waveform = 0.
	modulator.set_waveform(0);
	carrier.set_waveform(0);

	// Set FB = 0, use FM synthesis.
	channel.set_feedback_mode(1);

	// Set: AR = 15, DR = 0.
	modulator.set_attack_decay(0xf0);
	carrier.set_attack_decay(0xf0);

	// Set: SL = 0, RR = 15.
	modulator.set_sustain_release(0x0f);
	carrier.set_sustain_release(0x0f);

	// Set 16384 samples for 1 period, and key-on.
	channel.set_frequency_low(0x40);
	channel.set_9bit_frequency_octave_key_on(0x10);

	// Check one complete cycle of samples.
	NSEnumerator *goodValues = [knownGood objectEnumerator];
	for(int c = 0; c < 16384; ++c) {
		channel.update(true, oscillator, modulator);
		channel.update(false, oscillator, carrier);
		const int generated = channel.melodic_output(modulator, carrier);
		const int known = [[goodValues nextObject] intValue] >> 2;
		XCTAssertLessThanOrEqual(abs(generated - known), 30, "FM synthesis varies by more than 10 at sample %d of attenuation %d", c, attenuation);
	}
}

- (void)testFM {
	// The following have been verified by sight against
	// the images at https://www.smspower.org/Development/RE10
	// as "close enough". Sadly the raw data isn't given, so
	// that's the best as I can do. Fingers crossed!

	NSURL *const url = [[NSBundle bundleForClass:[self class]] URLForResource:@"fm"  withExtension:@"json"];
	NSArray *const parent = [NSJSONSerialization JSONObjectWithData:[NSData dataWithContentsOfURL:url] options:0 error:nil];

	for(int c = 0; c < 64; ++c) {
		[self compareFMTo:parent[c] atAttenuation:c];
	}
}

// MARK: - Level tests

- (int)maxLevelForOPLLAttenuation:(int)attenuation {
	Yamaha::OPL::Operator modulator, carrier;
	Yamaha::OPL::Channel channel;
	Yamaha::OPL::OperatorOverrides overrides;
	Yamaha::OPL::LowFrequencyOscillator oscillator;

	// Reach maximum volume immediately, and hold it during sustain.
	carrier.set_sustain_release(0x0f);
	carrier.set_attack_decay(0xf0);

	// Use FM synthesis.
	channel.set_feedback_mode(1);

	// Set hold sustain level.
	carrier.set_am_vibrato_hold_sustain_ksr_multiple(0x20);

	// Disable the modulator.
	modulator.set_scaling_output(0x3f);

	// Set a non-zero frequency, set key on.
	channel.set_frequency_low(0x40);
	channel.set_9bit_frequency_octave_key_on(0x10);

	// Get the maximum output for this volume level.
	overrides.attenuation = attenuation;
	overrides.use_sustain_level = true;

	int max = 0;
	for(int c = 0; c < 16384; ++c) {
		channel.update(true, oscillator, modulator);
		channel.update(false, oscillator, carrier, false, &overrides);
		const int level = channel.melodic_output(modulator, carrier);
		if(level > max) max = level;
	}

	return max;
}

- (void)testOPLLVolumeLevels {
	// Get maximum output levels for all channels.
	int maxLevels[16];
	for(int c = 0; c < 16; ++c) {
		maxLevels[c] = [self maxLevelForOPLLAttenuation:c];
	}

	// Figure out a divider to turn that into the sampled range.
	const double multiplier = 255.0 / double(maxLevels[0]);
	const double expectedLevels[16] = {255.0, 181.0, 127.0, 90.0, 63.0, 45.0, 31.0, 22.0, 15.0, 11.0, 7.0, 5.0, 3.0, 2.0, 1.0, 1.0};
	for(int c = 0; c < 16; ++c) {
		const double empiricalLevel = double(maxLevels[c]) * multiplier;
		XCTAssertLessThanOrEqual(fabs(round(empiricalLevel) - expectedLevels[c]), 2.0, "Fixed attenuation %d was %0.0f; should have been %0.0f", c, empiricalLevel, expectedLevels[c]);
	}
}

// MARK: - ADSR tests

- (void)testADSR {
//	Yamaha::OPL::Operator test_operator;
//	Yamaha::OPL::OperatorState test_state;
//
//	test_operator.set_attack_decay(0x88);
//	test_operator.set_sustain_release(0x88);
//
//	// While key is off, output level should remain at 0.
//	for(int c = 0; c < 1024; ++c) {
//		test_operator.update(test_state, false, 0, 0, 0);
//		XCTAssertGreaterThanOrEqual(test_state.level(), 0);
//	}
//
//	// Set key on...
//	for(int c = 0; c < 4096; ++c) {
//		test_operator.update(test_state, true, 0, 0, 0);
//		NSLog(@"%d", test_state.level());
//	}
}*/

@end