CLK/Components/OPL2/OPL2.cpp

//
//  OPL2.cpp
//  Clock Signal
//
//  Created by Thomas Harte on 02/04/2020.
//  Copyright © 2020 Thomas Harte. all rights reserved.
//

#include "OPL2.hpp"

#include <cmath>

namespace {

/*

	Credit for the fixed register lists goes to Nuke.YKT; I found them at:
	https://siliconpr0n.org/archive/doku.php?id=vendor:yamaha:opl2#ym2413_instrument_rom

	The arrays below begin with channel 1, each line is a single channel and the
	format per channel is, from first byte to eighth:

		Bytes 1 and 2:
			Registers 1 and 2, i.e. modulator and carrier
			amplitude modulation select, vibrato select, etc.

		Byte 3:
			b7, b6: modulator key scale level
			b5...b0: modulator total level (inverted)

		Byte 4:
			b7: carrier key scale level
			b3...b0: feedback level and waveform selects as per register 4

		Bytes 5, 6:
			Registers 4 and 5, i.e. decay and attack rate, modulator and carrier.

		Bytes 7, 8:
			Registers 6 and 7, i.e. decay-sustain level and release rate, modulator and carrier.

*/

constexpr uint8_t opll_patch_set[] = {
	0x71, 0x61, 0x1e, 0x17, 0xd0, 0x78, 0x00, 0x17,
	0x13, 0x41, 0x1a, 0x0d, 0xd8, 0xf7, 0x23, 0x13,
	0x13, 0x01, 0x99, 0x00, 0xf2, 0xc4, 0x11, 0x23,
	0x31, 0x61, 0x0e, 0x07, 0xa8, 0x64, 0x70, 0x27,
	0x32, 0x21, 0x1e, 0x06, 0xe0, 0x76, 0x00, 0x28,
	0x31, 0x22, 0x16, 0x05, 0xe0, 0x71, 0x00, 0x18,
	0x21, 0x61, 0x1d, 0x07, 0x82, 0x81, 0x10, 0x07,
	0x23, 0x21, 0x2d, 0x14, 0xa2, 0x72, 0x00, 0x07,
	0x61, 0x61, 0x1b, 0x06, 0x64, 0x65, 0x10, 0x17,
	0x41, 0x61, 0x0b, 0x18, 0x85, 0xf7, 0x71, 0x07,
	0x13, 0x01, 0x83, 0x11, 0xfa, 0xe4, 0x10, 0x04,
	0x17, 0xc1, 0x24, 0x07, 0xf8, 0xf8, 0x22, 0x12,
	0x61, 0x50, 0x0c, 0x05, 0xc2, 0xf5, 0x20, 0x42,
	0x01, 0x01, 0x55, 0x03, 0xc9, 0x95, 0x03, 0x02,
	0x61, 0x41, 0x89, 0x03, 0xf1, 0xe4, 0x40, 0x13,
};

constexpr uint8_t vrc7_patch_set[] = {
	0x03, 0x21, 0x05, 0x06, 0xe8, 0x81, 0x42, 0x27,
	0x13, 0x41, 0x14, 0x0d, 0xd8, 0xf6, 0x23, 0x12,
	0x11, 0x11, 0x08, 0x08, 0xfa, 0xb2, 0x20, 0x12,
	0x31, 0x61, 0x0c, 0x07, 0xa8, 0x64, 0x61, 0x27,
	0x32, 0x21, 0x1e, 0x06, 0xe1, 0x76, 0x01, 0x28,
	0x02, 0x01, 0x06, 0x00, 0xa3, 0xe2, 0xf4, 0xf4,
	0x21, 0x61, 0x1d, 0x07, 0x82, 0x81, 0x11, 0x07,
	0x23, 0x21, 0x22, 0x17, 0xa2, 0x72, 0x01, 0x17,
	0x35, 0x11, 0x25, 0x00, 0x40, 0x73, 0x72, 0x01,
	0xb5, 0x01, 0x0f, 0x0f, 0xa8, 0xa5, 0x51, 0x02,
	0x17, 0xc1, 0x24, 0x07, 0xf8, 0xf8, 0x22, 0x12,
	0x71, 0x23, 0x11, 0x06, 0x65, 0x74, 0x18, 0x16,
	0x01, 0x02, 0xd3, 0x05, 0xc9, 0x95, 0x03, 0x02,
	0x61, 0x63, 0x0c, 0x00, 0x94, 0xc0, 0x33, 0xf6,
	0x21, 0x72, 0x0d, 0x00, 0xc1, 0xd5, 0x56, 0x06,
};

constexpr uint8_t percussion_patch_set[] = {
	0x01, 0x01, 0x18, 0x0f, 0xdf, 0xf8, 0x6a, 0x6d,
	0x01, 0x01, 0x00, 0x00, 0xc8, 0xd8, 0xa7, 0x48,
	0x05, 0x01, 0x00, 0x00, 0xf8, 0xaa, 0x59, 0x55,
};

}

using namespace Yamaha;

OPL2::OPL2(Personality personality, Concurrency::DeferringAsyncTaskQueue &task_queue): task_queue_(task_queue) {
	(void)opll_patch_set;
	(void)vrc7_patch_set;
	(void)percussion_patch_set;

	// Populate the exponential and log-sine tables; formulas here taken from Matthew Gambrell
	// and Olli Niemitalo's decapping and reverse-engineering of the OPL2.
	for(int c = 0; c < 256; ++c) {
		exponential_[c] = int(round((pow(2.0, double(c) / 256.0) - 1.0) * 1024.0));

		const double sine = sin((double(c) + 0.5) * M_PI/512.0);
		log_sin_[c] = int(
			round(
				-log(sine) / log(2.0) * 256.0
			 )
		);
	}
}

bool OPL2::is_zero_level() {
	return true;
}

void OPL2::get_samples(std::size_t number_of_samples, std::int16_t *target) {
	// TODO.
	//  out = exp(logsin(phase2 + exp(logsin(phase1) + gain1)) + gain2)
}

void OPL2::set_sample_volume_range(std::int16_t range) {
	// TODO.
}

void OPL2::write(uint16_t address, uint8_t value) {
	if(address & 1) {
		set_opl2_register(selected_register_, value);
	} else {
		selected_register_ = value;
	}
}

uint8_t OPL2::read(uint16_t address) {
	// TODO.
	return 0xff;
}

void OPL2::set_opl2_register(uint8_t location, uint8_t value) {
	printf("OPL2 write: %02x to %d\n", value, selected_register_);

	// Deal with timer changes synchronously.
	switch(location) {
		case 0x02:	timers_[0] = value; 	return;
		case 0x03:	timers_[1] = value;		return;
		case 0x04:	timer_control_ = value;	return;

		default: break;
	}

	// Enqueue any changes that affect audio output.
	task_queue_.enqueue([this, location, value] {

		//
		// Operator modifications.
		//

		if(location >= 0x20 && location <= 0x35) {
			operators_[location - 0x20].apply_amplitude_modulation = value & 0x80;
			operators_[location - 0x20].apply_vibrato = value & 0x40;
			operators_[location - 0x20].hold_sustain_level = value & 0x20;
			operators_[location - 0x20].keyboard_scaling_rate = value & 0x10;
			operators_[location - 0x20].frequency_multiple = value & 0xf;
			return;
		}

		if(location >= 0x40 && location <= 0x55) {
			operators_[location - 0x40].scaling_level = value >> 6;
			operators_[location - 0x40].output_level = value & 0x3f;
			return;
		}

		if(location >= 0x60 && location <= 0x75) {
			operators_[location - 0x60].attack_rate = value >> 5;
			operators_[location - 0x60].decay_rate = value & 0xf;
			return;
		}

		if(location >= 0x80 && location <= 0x95) {
			operators_[location - 0x60].sustain_level = value >> 5;
			operators_[location - 0x60].release_rate = value & 0xf;
			return;
		}

		if(location >= 0xe0 && location <= 0xf5) {
			operators_[location - 0xe0].waveform = value & 3;
			return;
		}


		//
		// Channel modifications.
		//

		if(location >= 0xa0 && location <= 0xa8) {
			channels_[location - 0xa0].frequency = (channels_[location - 0xa0].frequency & ~0xff) | value;
			return;
		}

		if(location >= 0xb0 && location <= 0xb8) {
			channels_[location - 0xb0].frequency = (channels_[location - 0xb0].frequency & 0xff) | ((value & 3) << 8);
			channels_[location - 0xb0].octave = (value >> 2) & 0x7;
			channels_[location - 0xb0].key_on = value & 0x20;;
			return;
		}

		if(location >= 0xc0 && location <= 0xc8) {
			channels_[location - 0xc0].feedback_strength = (value >> 1) & 0x7;
			channels_[location - 0xc0].two_operator = value & 1;
			return;
		}


		//
		// Modal modifications.
		//
		switch(location) {
			case 0x01:	waveform_enable_ = value & 0x20;	break;
			case 0x08:	csm_keyboard_split_ = value;		break;
			case 0xbd:	depth_rhythm_control_ = value;		break;

			default: break;
		}
	});
}