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379 lines
11 KiB
C++
379 lines
11 KiB
C++
//
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// OPL2.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 02/04/2020.
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// Copyright © 2020 Thomas Harte. all rights reserved.
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//
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#include "OPL2.hpp"
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#include <cmath>
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namespace {
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/*
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Credit for the fixed register lists goes to Nuke.YKT; I found them at:
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https://siliconpr0n.org/archive/doku.php?id=vendor:yamaha:opl2#ym2413_instrument_rom
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The arrays below begin with channel 1, each line is a single channel and the
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format per channel is, from first byte to eighth:
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Bytes 1 and 2:
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Registers 1 and 2, i.e. modulator and carrier
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amplitude modulation select, vibrato select, etc.
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Byte 3:
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b7, b6: modulator key scale level
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b5...b0: modulator total level (inverted)
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Byte 4:
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b7: carrier key scale level
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b3...b0: feedback level and waveform selects as per register 4
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Bytes 5, 6:
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Registers 4 and 5, i.e. decay and attack rate, modulator and carrier.
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Bytes 7, 8:
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Registers 6 and 7, i.e. decay-sustain level and release rate, modulator and carrier.
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*/
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constexpr uint8_t opll_patch_set[] = {
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0x71, 0x61, 0x1e, 0x17, 0xd0, 0x78, 0x00, 0x17,
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0x13, 0x41, 0x1a, 0x0d, 0xd8, 0xf7, 0x23, 0x13,
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0x13, 0x01, 0x99, 0x00, 0xf2, 0xc4, 0x11, 0x23,
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0x31, 0x61, 0x0e, 0x07, 0xa8, 0x64, 0x70, 0x27,
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0x32, 0x21, 0x1e, 0x06, 0xe0, 0x76, 0x00, 0x28,
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0x31, 0x22, 0x16, 0x05, 0xe0, 0x71, 0x00, 0x18,
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0x21, 0x61, 0x1d, 0x07, 0x82, 0x81, 0x10, 0x07,
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0x23, 0x21, 0x2d, 0x14, 0xa2, 0x72, 0x00, 0x07,
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0x61, 0x61, 0x1b, 0x06, 0x64, 0x65, 0x10, 0x17,
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0x41, 0x61, 0x0b, 0x18, 0x85, 0xf7, 0x71, 0x07,
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0x13, 0x01, 0x83, 0x11, 0xfa, 0xe4, 0x10, 0x04,
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0x17, 0xc1, 0x24, 0x07, 0xf8, 0xf8, 0x22, 0x12,
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0x61, 0x50, 0x0c, 0x05, 0xc2, 0xf5, 0x20, 0x42,
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0x01, 0x01, 0x55, 0x03, 0xc9, 0x95, 0x03, 0x02,
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0x61, 0x41, 0x89, 0x03, 0xf1, 0xe4, 0x40, 0x13,
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};
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constexpr uint8_t vrc7_patch_set[] = {
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0x03, 0x21, 0x05, 0x06, 0xe8, 0x81, 0x42, 0x27,
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0x13, 0x41, 0x14, 0x0d, 0xd8, 0xf6, 0x23, 0x12,
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0x11, 0x11, 0x08, 0x08, 0xfa, 0xb2, 0x20, 0x12,
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0x31, 0x61, 0x0c, 0x07, 0xa8, 0x64, 0x61, 0x27,
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0x32, 0x21, 0x1e, 0x06, 0xe1, 0x76, 0x01, 0x28,
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0x02, 0x01, 0x06, 0x00, 0xa3, 0xe2, 0xf4, 0xf4,
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0x21, 0x61, 0x1d, 0x07, 0x82, 0x81, 0x11, 0x07,
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0x23, 0x21, 0x22, 0x17, 0xa2, 0x72, 0x01, 0x17,
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0x35, 0x11, 0x25, 0x00, 0x40, 0x73, 0x72, 0x01,
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0xb5, 0x01, 0x0f, 0x0f, 0xa8, 0xa5, 0x51, 0x02,
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0x17, 0xc1, 0x24, 0x07, 0xf8, 0xf8, 0x22, 0x12,
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0x71, 0x23, 0x11, 0x06, 0x65, 0x74, 0x18, 0x16,
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0x01, 0x02, 0xd3, 0x05, 0xc9, 0x95, 0x03, 0x02,
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0x61, 0x63, 0x0c, 0x00, 0x94, 0xc0, 0x33, 0xf6,
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0x21, 0x72, 0x0d, 0x00, 0xc1, 0xd5, 0x56, 0x06,
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};
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constexpr uint8_t percussion_patch_set[] = {
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0x01, 0x01, 0x18, 0x0f, 0xdf, 0xf8, 0x6a, 0x6d,
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0x01, 0x01, 0x00, 0x00, 0xc8, 0xd8, 0xa7, 0x48,
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0x05, 0x01, 0x00, 0x00, 0xf8, 0xaa, 0x59, 0x55,
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};
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}
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using namespace Yamaha;
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// MARK: - Construction
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OPL2::OPL2(Personality personality, Concurrency::DeferringAsyncTaskQueue &task_queue): task_queue_(task_queue), personality_(personality) {
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// Populate the exponential and log-sine tables; formulas here taken from Matthew Gambrell
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// and Olli Niemitalo's decapping and reverse-engineering of the OPL2.
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for(int c = 0; c < 256; ++c) {
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exponential_[c] = int(round((pow(2.0, double(c) / 256.0) - 1.0) * 1024.0));
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const double sine = sin((double(c) + 0.5) * M_PI/512.0);
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log_sin_[c] = int(
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round(
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-log(sine) / log(2.0) * 256.0
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)
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);
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}
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// TODO: use this when in OPLL percussion mode.
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(void)percussion_patch_set;
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}
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// MARK: - Audio Generation
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bool OPL2::is_zero_level() {
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return true;
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}
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void OPL2::get_samples(std::size_t number_of_samples, std::int16_t *target) {
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// TODO.
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// out = exp(logsin(phase2 + exp(logsin(phase1) + gain1)) + gain2)
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/*
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Melodic channels are:
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Channel Operator 1 Operator 2
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0 0 3
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1 1 4
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2 2 5
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3 6 9
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4 7 10
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5 8 11
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6 12 15
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7 13 16
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8 14 17
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In percussion mode, only channels 0–5 are use as melodic, with 6, 7 and 8 being
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replaced by:
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Bass drum, using operators 12 and 15;
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Snare, using operator 16;
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Tom tom, using operator 14,
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Cymbal, using operator 17; and
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Symbol, using operator 13.
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*/
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}
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void OPL2::set_sample_volume_range(std::int16_t range) {
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// TODO.
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}
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// MARK: - Software Interface
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void OPL2::write(uint16_t address, uint8_t value) {
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if(address & 1) {
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switch(personality_) {
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case Personality::OPL2:
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set_opl2_register(selected_register_, value);
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break;
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default:
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set_opll_register(selected_register_, value);
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break;
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}
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} else {
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selected_register_ = value;
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}
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}
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uint8_t OPL2::read(uint16_t address) {
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// TODO. There's a status register where:
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// b7 = IRQ status (set if interrupt request ongoing)
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// b6 = timer 1 flag (set if timer 1 expired)
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// b5 = timer 2 flag
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return 0xff;
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}
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void OPL2::set_opll_register(uint8_t location, uint8_t value) {
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if(location < 8) {
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opll_custom_instrument_[location] = value;
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// Repush this instrument for any channels it's presently selected on.
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for(int c = 0; c < 9; ++c) {
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if(!(instrument_selections_[c] >> 4)) {
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set_opll_instrument(uint8_t(c), 0, instrument_selections_[c] & 0xf);
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}
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}
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return;
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}
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if(location >= 0x30 && location <= 0x38) {
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instrument_selections_[location - 0x30] = value;
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set_opll_instrument(location - 0x30, value >> 4, value & 0xf);
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return;
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}
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if(location == 0xe) {
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set_opl2_register(0xbd, value & 0x3f);
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return;
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}
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if(location >= 0x10 && location <= 0x18) {
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set_opl2_register(location - 0x10 + 0xa0, value);
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return;
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}
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if(location >= 0x20 && location <= 0x28) {
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const auto index = location = 0x20;
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operators_[index].hold_sustain_level = value & 0x20;
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// Only the bottom bit contributes to the frequency on an OPLL; on an OPL2 it's the two
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// bottom bits (and hold-sustain isn't set in the same register).
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set_opl2_register(index + 0xb0, uint8_t((value & 1) | ((value & 0xfe) << 1)));
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return;
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}
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}
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void OPL2::set_opll_instrument(uint8_t target, uint8_t source_instrument, uint8_t volume) {
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const uint8_t *source;
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if(!source_instrument) {
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source = opll_custom_instrument_;
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} else {
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--source_instrument;
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source =
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(source_instrument * 8) +
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(personality_ == Personality::OPLL ? opll_patch_set : vrc7_patch_set);
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}
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constexpr uint8_t offsets[9][2] = {
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{0x00, 0x03},
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{0x01, 0x04},
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{0x02, 0x05},
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{0x08, 0x0b},
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{0x09, 0x0c},
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{0x0a, 0x0d},
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{0x10, 0x13},
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{0x11, 0x14},
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{0x12, 0x15},
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};
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const auto carrier = offsets[target][0];
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const auto modulator = offsets[target][1];
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// Set waveforms — only sine and halfsine are available.
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set_opl2_register(0xe0 + carrier, (source[3] & 0x10) ? 1 : 0);
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set_opl2_register(0xe0 + modulator, (source[3] & 0x08) ? 1 : 0);
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// Volume on the OPLL is four bit; on the OPL2 it's six. Pair that with key scale level.
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set_opl2_register(0xe0 + carrier, uint8_t((source[3] & 0xc0) | (volume << 2)));
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// Set feedback level, which is per channel. And always set frequency modulation.
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set_opl2_register(0xc0 + target, uint8_t((source[3] & 0x7) << 1));
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// The other values don't require any mapping.
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set_opl2_register(0x20 + carrier, source[0]);
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set_opl2_register(0x20 + modulator, source[1]);
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set_opl2_register(0x40 + carrier, source[2]);
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set_opl2_register(0x60 + carrier, source[4]);
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set_opl2_register(0x60 + modulator, source[5]);
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set_opl2_register(0x80 + carrier, source[6]);
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set_opl2_register(0x80 + modulator, source[7]);
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}
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void OPL2::set_opl2_register(uint8_t location, uint8_t value) {
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printf("OPL2 write: %02x to %d\n", value, selected_register_);
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// Deal with timer changes synchronously.
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switch(location) {
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case 0x02: timers_[0] = value; return;
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case 0x03: timers_[1] = value; return;
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case 0x04: timer_control_ = value; return;
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// TODO from register 4:
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// b7 = IRQ reset;
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// b6/b5 = timer 1/2 mask (irq enabling flags, I think?)
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// b4/b3 = timer 2/1 start (seemingly the opposite order to b6/b5?)
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default: break;
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}
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// Enqueue any changes that affect audio output.
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task_queue_.enqueue([this, location, value] {
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//
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// Operator modifications.
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//
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// The 18 operators are spreat out across 22 addresses; each group of
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// six is framed within an eight-byte area thusly:
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constexpr int operator_by_address[] = {
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0, 1, 2, 3, 4, 5, -1, -1,
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6, 7, 8, 9, 10, 11, -1, -1,
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12, 13, 14, 15, 16, 17, -1, -1
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};
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if(location >= 0x20 && location <= 0x35) {
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const auto index = operator_by_address[location - 0x20];
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if(index == -1) return;
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operators_[index].apply_amplitude_modulation = value & 0x80;
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operators_[index].apply_vibrato = value & 0x40;
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operators_[index].hold_sustain_level = value & 0x20;
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operators_[index].keyboard_scaling_rate = value & 0x10;
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operators_[index].frequency_multiple = value & 0xf;
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return;
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}
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if(location >= 0x40 && location <= 0x55) {
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const auto index = operator_by_address[location - 0x40];
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if(index == -1) return;
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operators_[index].scaling_level = value >> 6;
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operators_[index].output_level = value & 0x3f;
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return;
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}
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if(location >= 0x60 && location <= 0x75) {
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const auto index = operator_by_address[location - 0x60];
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if(index == -1) return;
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operators_[index].attack_rate = value >> 5;
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operators_[index].decay_rate = value & 0xf;
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return;
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}
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if(location >= 0x80 && location <= 0x95) {
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const auto index = operator_by_address[location - 0x80];
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if(index == -1) return;
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operators_[index].sustain_level = value >> 5;
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operators_[index].release_rate = value & 0xf;
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return;
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}
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if(location >= 0xe0 && location <= 0xf5) {
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const auto index = operator_by_address[location - 0xe0];
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if(index == -1) return;
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operators_[index].waveform = value & 3;
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return;
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}
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//
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// Channel modifications.
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//
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if(location >= 0xa0 && location <= 0xa8) {
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channels_[location - 0xa0].frequency = (channels_[location - 0xa0].frequency & ~0xff) | value;
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return;
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}
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if(location >= 0xb0 && location <= 0xb8) {
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channels_[location - 0xb0].frequency = (channels_[location - 0xb0].frequency & 0xff) | ((value & 3) << 8);
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channels_[location - 0xb0].octave = (value >> 2) & 0x7;
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channels_[location - 0xb0].key_on = value & 0x20;;
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return;
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}
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if(location >= 0xc0 && location <= 0xc8) {
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channels_[location - 0xc0].feedback_strength = (value >> 1) & 0x7;
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channels_[location - 0xc0].use_fm_synthesis = value & 1;
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return;
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}
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//
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// Modal modifications.
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//
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switch(location) {
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case 0x01: waveform_enable_ = value & 0x20; break;
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case 0x08:
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// b7: "composite sine wave mode on/off"?
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csm_keyboard_split_ = value;
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// b6: "Controls the split point of the keyboard. When 0, the keyboard split is the
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// second bit from the bit 8 of the F-Number. When 1, the MSB of the F-Number is used."
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break;
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case 0xbd: depth_rhythm_control_ = value; break;
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default: break;
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}
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});
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}
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