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116 lines
3.1 KiB
C++
116 lines
3.1 KiB
C++
//
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// KonamiSCC.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 06/01/2018.
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// Copyright 2018 Thomas Harte. All rights reserved.
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//
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#include "KonamiSCC.hpp"
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#include <cstring>
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using namespace Konami;
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SCC::SCC(Concurrency::DeferringAsyncTaskQueue &task_queue) :
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task_queue_(task_queue) {}
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bool SCC::is_zero_level() const {
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return !(channel_enable_ & 0x1f);
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}
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void SCC::get_samples(std::size_t number_of_samples, std::int16_t *target) {
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if(is_zero_level()) {
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std::memset(target, 0, sizeof(std::int16_t) * number_of_samples);
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return;
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}
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std::size_t c = 0;
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while((master_divider_&7) && c < number_of_samples) {
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target[c] = transient_output_level_;
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master_divider_++;
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c++;
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}
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while(c < number_of_samples) {
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for(int channel = 0; channel < 5; ++channel) {
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if(channels_[channel].tone_counter) channels_[channel].tone_counter--;
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else {
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channels_[channel].offset = (channels_[channel].offset + 1) & 0x1f;
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channels_[channel].tone_counter = channels_[channel].period;
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}
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}
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evaluate_output_volume();
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for(int ic = 0; ic < 8 && c < number_of_samples; ++ic) {
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target[c] = transient_output_level_;
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c++;
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master_divider_++;
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}
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}
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}
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void SCC::write(uint16_t address, uint8_t value) {
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address &= 0xff;
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if(address < 0x80) ram_[address] = value;
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task_queue_.defer([this, address, value] {
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// Check for a write into waveform memory.
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if(address < 0x80) {
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waves_[address >> 5].samples[address & 0x1f] = value;
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} else switch(address) {
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default: break;
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case 0x80: case 0x82: case 0x84: case 0x86: case 0x88: {
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int channel = (address - 0x80) >> 1;
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channels_[channel].period = (channels_[channel].period & ~0xff) | value;
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} break;
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case 0x81: case 0x83: case 0x85: case 0x87: case 0x89: {
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int channel = (address - 0x80) >> 1;
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channels_[channel].period = (channels_[channel].period & 0xff) | ((value & 0xf) << 8);
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} break;
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case 0x8a: case 0x8b: case 0x8c: case 0x8d: case 0x8e:
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channels_[address - 0x8a].amplitude = value & 0xf;
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break;
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case 0x8f:
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channel_enable_ = value;
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break;
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}
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evaluate_output_volume();
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});
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}
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void SCC::evaluate_output_volume() {
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transient_output_level_ =
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int16_t(
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((
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(channel_enable_ & 0x01) ? int8_t(waves_[0].samples[channels_[0].offset]) * channels_[0].amplitude : 0 +
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(channel_enable_ & 0x02) ? int8_t(waves_[1].samples[channels_[1].offset]) * channels_[1].amplitude : 0 +
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(channel_enable_ & 0x04) ? int8_t(waves_[2].samples[channels_[2].offset]) * channels_[2].amplitude : 0 +
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(channel_enable_ & 0x08) ? int8_t(waves_[3].samples[channels_[3].offset]) * channels_[3].amplitude : 0 +
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(channel_enable_ & 0x10) ? int8_t(waves_[3].samples[channels_[4].offset]) * channels_[4].amplitude : 0
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) * master_volume_) / (255*15*5)
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// Five channels, each with 8-bit samples and 4-bit volumes implies a natural range of 0 to 255*15*5.
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);
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}
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void SCC::set_sample_volume_range(std::int16_t range) {
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master_volume_ = range;
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evaluate_output_volume();
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}
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uint8_t SCC::read(uint16_t address) {
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address &= 0xff;
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if(address < 0x80) {
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return ram_[address];
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}
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return 0xff;
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}
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