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Attempts to add the missing noise generators. I think I may still be astray on volumes.

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This commit is contained in:
Thomas Harte 2020-04-26 15:51:33 -04:00
parent 2bc36a6cde
commit 9f0c8bcae7
2 changed files with 46 additions and 21 deletions
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52
Components/OPL2/Implementation/Operator.cpp
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@ -245,7 +245,10 @@ void Operator::update(
// MARK: - Output Generators. // MARK: - Output Generators.
LogSign Operator::melodic_output(OperatorState &state, const LogSign *phase_offset) { // A heavy debt is owed to https://github.com/andete/ym2413/blob/master/results/rhythm/rhythm.md regarding
// the drum sound generation below.
LogSign Operator::melodic_output(const OperatorState &state, const LogSign *phase_offset) {
// Calculate raw attenuation level. // Calculate raw attenuation level.
constexpr int waveforms[4][4] = { constexpr int waveforms[4][4] = {
{1023, 1023, 1023, 1023}, // Sine: don't mask in any quadrant. {1023, 1023, 1023, 1023}, // Sine: don't mask in any quadrant.
@ -262,33 +265,44 @@ LogSign Operator::melodic_output(OperatorState &state, const LogSign *phase_offs
return result; return result;
} }
LogSign Operator::snare_output(OperatorState &state) { LogSign Operator::snare_output(const OperatorState &state) {
LogSign result; LogSign result;
// If noise is 0, output is positive. // If noise is 0, output is positive.
// If noise is 1, output is negative. // If noise is 1, output is negative.
// If (noise ^ sign) is 0, output is 0. Otherwise it is max. // If (noise ^ sign) is 0, output is 0. Otherwise it is max.
// const int angle = ((state.lfsr_ << 10) ^ (state.raw_phase_ >> 12)) & 0x100;
//
// result = negative_log_sin((state.raw_phase_ >> 11) &;
// constexpr int masks[] = {~0, 0};
// result += masks[state.lfsr_
const int sign = (state.raw_phase_ >> 11) & 0x200; const int sign = (state.raw_phase_ >> 11) & 0x200;
const int level = ((state.raw_phase_ >> 20) & 1) ^ state.lfsr_; const int level = ((state.raw_phase_ >> 20) & 1) ^ state.lfsr_;
result = negative_log_sin(sign + (level << 8)); result = negative_log_sin(sign + (level << 8));
// if((state.raw_phase_ >> 11) & 0x200) { result += state.key_level_scaling_;
// // Result is -max if LFSR is 0, otherwise -0. result += state.channel_adsr_attenuation_;
// result = negative_log_sin(512 + ((state.lfsr_^1) << 8)); return result;
// } else { }
// // Result is +max if LFSR is 1, otherwise +0.
// result = negative_log_sin(state.lfsr_ << 8); LogSign Operator::cymbal_output(const OperatorState &state, const OperatorState &modulator) {
// } const int output =
((state.raw_phase_ >> 16) ^ (state.raw_phase_ >> 14)) &
((modulator.raw_phase_ >> 18) ^ (modulator.raw_phase_ >> 13)) &
// printf("%d %d: %d/%d\n", state.lfsr_, (state.raw_phase_ >> 11) & 1023, result.log, result.sign); ((state.raw_phase_ >> 16) ^ (modulator.raw_phase_ >> 14));
constexpr int angles[] = {256, 768};
LogSign result = negative_log_sin(angles[output & 1]);
result += state.key_level_scaling_;
result += state.channel_adsr_attenuation_;
return result;
}
LogSign Operator::high_hat_output(const OperatorState &state, const OperatorState &modulator) {
const int output =
((state.raw_phase_ >> 16) ^ (state.raw_phase_ >> 14)) &
((modulator.raw_phase_ >> 18) ^ (modulator.raw_phase_ >> 13)) &
((state.raw_phase_ >> 16) ^ (modulator.raw_phase_ >> 14));
constexpr int angles[] = {0x234, 0xd0, 0x2d0, 0x34};
LogSign result = negative_log_sin(angles[(output & 1) | (state.lfsr_ << 1)]);
result += state.key_level_scaling_; result += state.key_level_scaling_;
result += state.channel_adsr_attenuation_; result += state.channel_adsr_attenuation_;
return result; return result;

15
Components/OPL2/Implementation/Operator.hpp
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@ -94,8 +94,19 @@ class Operator {
/// @returns @c true if this channel currently has a non-zero output; @c false otherwise. /// @returns @c true if this channel currently has a non-zero output; @c false otherwise.
bool is_audible(OperatorState &state, OperatorOverrides *overrides = nullptr); bool is_audible(OperatorState &state, OperatorOverrides *overrides = nullptr);
LogSign melodic_output(OperatorState &state, const LogSign *phase_offset = nullptr); /// Provides ordinary melodic output, optionally with modulation.
LogSign snare_output(OperatorState &state); LogSign melodic_output(const OperatorState &state, const LogSign *phase_offset = nullptr);
/// Provides snare drum output, which is a function of phase and the captured LFSR level.
LogSign snare_output(const OperatorState &state);
/// Provides cymbal output, which is a function of the phase given by @c state, ordinarily the carrier of channel 8,
/// and the phase of @c modulator, which is ordinarily the modulator of channel 7.
LogSign cymbal_output(const OperatorState &state, const OperatorState &modulator);
/// Provides high-hat output, which is a function of the phase given by @c state, ordinarily the carrier of channel 8,
/// and the phase of @c modulator, which is ordinarily the modulator of channel 7.
LogSign high_hat_output(const OperatorState &state, const OperatorState &modulator);
private: private:
/// If true then an amplitude modulation of "3.7Hz" is applied, /// If true then an amplitude modulation of "3.7Hz" is applied,