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Adds optional stereo output for the AY.
The real chip provides the three tone channels as separate outputs, so a variety of different mixings can exist.
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@ -84,10 +84,33 @@ void AY38910::set_sample_volume_range(std::int16_t range) {
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for(int v = 31; v >= 0; --v) {
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volumes_[v] -= volumes_[0];
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}
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evaluate_output_volume();
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if(is_stereo_) {
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evaluate_output_volume<true>();
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} else {
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evaluate_output_volume<false>();
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}
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}
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void AY38910::set_output_mixing(bool is_stereo, float a_left, float b_left, float c_left, float a_right, float b_right, float c_right) {
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is_stereo_ = is_stereo;
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a_left_ = uint8_t(a_left * 255.0f);
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b_left_ = uint8_t(b_left * 255.0f);
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c_left_ = uint8_t(c_left * 255.0f);
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a_right_ = uint8_t(a_right * 255.0f);
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b_right_ = uint8_t(b_right * 255.0f);
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c_right_ = uint8_t(c_right * 255.0f);
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}
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void AY38910::get_samples(std::size_t number_of_samples, int16_t *target) {
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if(is_stereo_) {
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get_samples<true>(number_of_samples, target);
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} else {
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get_samples<false>(number_of_samples, target);
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}
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}
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template <bool is_stereo> void AY38910::get_samples(std::size_t number_of_samples, int16_t *target) {
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// Note on structure below: the real AY has a built-in divider of 8
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// prior to applying its tone and noise dividers. But the YM fills the
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// same total periods for noise and tone with double-precision envelopes.
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@ -99,7 +122,11 @@ void AY38910::get_samples(std::size_t number_of_samples, int16_t *target) {
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std::size_t c = 0;
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while((master_divider_&3) && c < number_of_samples) {
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target[c] = output_volume_;
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if constexpr (is_stereo) {
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reinterpret_cast<uint32_t *>(target)[c] = output_volume_;
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} else {
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target[c] = output_volume_;
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}
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master_divider_++;
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c++;
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}
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@ -138,10 +165,14 @@ void AY38910::get_samples(std::size_t number_of_samples, int16_t *target) {
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if(envelope_position_ == 64) envelope_position_ = envelope_overflow_masks_[output_registers_[13]];
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}
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evaluate_output_volume();
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evaluate_output_volume<is_stereo>();
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for(int ic = 0; ic < 4 && c < number_of_samples; ic++) {
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target[c] = output_volume_;
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if constexpr (is_stereo) {
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reinterpret_cast<uint32_t *>(target)[c] = output_volume_;
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} else {
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target[c] = output_volume_;
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}
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c++;
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master_divider_++;
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}
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@ -150,7 +181,7 @@ void AY38910::get_samples(std::size_t number_of_samples, int16_t *target) {
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master_divider_ &= 3;
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}
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void AY38910::evaluate_output_volume() {
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template <bool is_stereo> void AY38910::evaluate_output_volume() {
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int envelope_volume = envelope_shapes_[output_registers_[13]][envelope_position_ | envelope_position_mask_];
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// The output level for a channel is:
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@ -190,12 +221,26 @@ void AY38910::evaluate_output_volume() {
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};
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#undef channel_volume
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// Mix additively.
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output_volume_ = int16_t(
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volumes_[volumes[0]] * channel_levels[0] +
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volumes_[volumes[1]] * channel_levels[1] +
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volumes_[volumes[2]] * channel_levels[2]
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);
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// Mix additively, weighting if in stereo.
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if constexpr (is_stereo) {
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int16_t *const volumes = reinterpret_cast<int16_t *>(&output_volume_);
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volumes[0] = int16_t((
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volumes_[volumes[0]] * channel_levels[0] * a_left_ +
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volumes_[volumes[1]] * channel_levels[1] * b_left_ +
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volumes_[volumes[2]] * channel_levels[2] * c_left_
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) >> 8);
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volumes[1] = int16_t((
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volumes_[volumes[0]] * channel_levels[0] * a_right_ +
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volumes_[volumes[1]] * channel_levels[1] * b_right_ +
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volumes_[volumes[2]] * channel_levels[2] * c_right_
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) >> 8);
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} else {
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output_volume_ = int16_t(
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volumes_[volumes[0]] * channel_levels[0] +
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volumes_[volumes[1]] * channel_levels[1] +
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volumes_[volumes[2]] * channel_levels[2]
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);
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}
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}
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bool AY38910::is_zero_level() {
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@ -252,7 +297,11 @@ void AY38910::set_register_value(uint8_t value) {
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// Store a copy of the current register within the storage used by the audio generation
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// thread, and apply any changes to output volume.
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output_registers_[selected_register] = masked_value;
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evaluate_output_volume();
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if(is_stereo_) {
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evaluate_output_volume<true>();
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} else {
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evaluate_output_volume<false>();
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}
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});
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}
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@ -63,6 +63,8 @@ enum class Personality {
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Provides emulation of an AY-3-8910 / YM2149, which is a three-channel sound chip with a
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noise generator and a volume envelope generator, which also provides two bidirectional
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interface ports.
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This AY has an attached mono or stereo mixer.
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*/
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class AY38910: public ::Outputs::Speaker::SampleSource {
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public:
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@ -91,6 +93,18 @@ class AY38910: public ::Outputs::Speaker::SampleSource {
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*/
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void set_port_handler(PortHandler *);
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/*!
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Enables or disables stereo output; if stereo output is enabled then also sets the weight of each of the AY's
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channels in each of the output channels.
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If a_left_ = b_left = c_left = a_right = b_right = c_right = 1.0 then you'll get output that's effectively mono.
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a_left = 0.0, a_right = 1.0 will make A full volume on the right output, and silent on the left.
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a_left = 0.5, a_right = 0.5 will make A half volume on both outputs.
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*/
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void set_output_mixing(bool is_stereo, float a_left, float b_left, float c_left, float a_right, float b_right, float c_right);
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// to satisfy ::Outputs::Speaker (included via ::Outputs::Filter.
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void get_samples(std::size_t number_of_samples, int16_t *target);
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bool is_zero_level();
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@ -135,12 +149,20 @@ class AY38910: public ::Outputs::Speaker::SampleSource {
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uint8_t data_input_, data_output_;
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int16_t output_volume_;
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void evaluate_output_volume();
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uint32_t output_volume_;
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void update_bus();
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PortHandler *port_handler_ = nullptr;
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void set_port_output(bool port_b);
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template <bool is_stereo> void get_samples(std::size_t number_of_samples, int16_t *target);
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template <bool is_stereo> void evaluate_output_volume();
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// Output mixing control.
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bool is_stereo_ = false;
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uint8_t a_left_ = 255, a_right_ = 255;
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uint8_t b_left_ = 255, b_right_ = 255;
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uint8_t c_left_ = 255, c_right_ = 255;
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};
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}
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