2021-06-22 23:33:41 +00:00
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//
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// Dave.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 22/06/2021.
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// Copyright © 2021 Thomas Harte. All rights reserved.
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//
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#include "Dave.hpp"
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using namespace Enterprise;
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2021-06-25 02:21:01 +00:00
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Dave::Dave(Concurrency::DeferringAsyncTaskQueue &audio_queue) :
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audio_queue_(audio_queue) {}
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2021-06-22 23:33:41 +00:00
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void Dave::write(uint16_t address, uint8_t value) {
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2021-06-25 02:21:01 +00:00
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address &= 0xf;
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audio_queue_.defer([address, value, this] {
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switch(address) {
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case 0: case 2: case 4:
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channels_[address >> 1].reload = (channels_[address >> 1].reload & 0xff00) | value;
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break;
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case 1: case 3: case 5:
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channels_[address >> 1].reload = uint16_t((channels_[address >> 1].reload & 0x00ff) | ((value & 0xf) << 4));
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channels_[address >> 1].distortion = Channel::Distortion((value >> 4)&3);
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channels_[address >> 1].high_pass = value & 0x40;
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channels_[address >> 1].ring_modulate = value & 0x80;
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break;
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// TODO:
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//
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// 6: noise selection.
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// 7: sync bits, optional D/As, interrupt rate (albeit some of that shouldn't be on this thread, or possibly even _here_).
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// 11, 14: noise amplitude.
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case 8: case 9: case 10:
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channels_[address - 8].amplitude[0] = value & 0x3f;
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break;
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case 11: case 12: case 13:
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channels_[address - 11].amplitude[1] = value & 0x3f;
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break;
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}
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});
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}
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void Dave::get_samples(std::size_t number_of_samples, int16_t *target) {
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// Step 1: divide input clock to 125,000 Hz (?)
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for(size_t c = 0; c < number_of_samples; c++) {
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#define update_channel(x) \
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--channels_[x].count; \
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if(!channels_[x].count) { \
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channels_[x].output ^= true; \
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channels_[x].count = channels_[x].reload; \
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}
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update_channel(0);
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update_channel(1);
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update_channel(2);
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#undef update_channel
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// Dumbest ever first attempt: sum channels.
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target[(c << 1) + 0] =
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channels_[0].amplitude[0] * channels_[0].output +
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channels_[1].amplitude[0] * channels_[1].output +
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channels_[2].amplitude[0] * channels_[2].output;
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target[(c << 1) + 1] =
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channels_[0].amplitude[1] * channels_[0].output +
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channels_[1].amplitude[1] * channels_[1].output +
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channels_[2].amplitude[1] * channels_[2].output;
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}
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2021-06-22 23:33:41 +00:00
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}
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