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125 lines
3.4 KiB
C++
125 lines
3.4 KiB
C++
//
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// Speaker.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 03/12/2016.
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// Copyright © 2016 Thomas Harte. All rights reserved.
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//
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#include "Speaker.hpp"
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using namespace Atari2600;
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Atari2600::Speaker::Speaker() :
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poly4_counter_{0x00f, 0x00f},
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poly5_counter_{0x01f, 0x01f},
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poly9_counter_{0x1ff, 0x1ff}
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{}
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void Atari2600::Speaker::set_volume(int channel, uint8_t volume) {
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enqueue([=]() {
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volume_[channel] = volume & 0xf;
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});
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}
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void Atari2600::Speaker::set_divider(int channel, uint8_t divider) {
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enqueue([=]() {
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divider_[channel] = divider & 0x1f;
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divider_counter_[channel] = 0;
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});
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}
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void Atari2600::Speaker::set_control(int channel, uint8_t control) {
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enqueue([=]() {
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control_[channel] = control & 0xf;
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});
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}
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#define advance_poly4(c) poly4_counter_[channel] = (poly4_counter_[channel] >> 1) | (((poly4_counter_[channel] << 3) ^ (poly4_counter_[channel] << 2))&0x008)
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#define advance_poly5(c) poly5_counter_[channel] = (poly5_counter_[channel] >> 1) | (((poly5_counter_[channel] << 4) ^ (poly5_counter_[channel] << 2))&0x010)
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#define advance_poly9(c) poly9_counter_[channel] = (poly9_counter_[channel] >> 1) | (((poly9_counter_[channel] << 4) ^ (poly9_counter_[channel] << 8))&0x100)
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void Atari2600::Speaker::get_samples(unsigned int number_of_samples, int16_t *target) {
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for(unsigned int c = 0; c < number_of_samples; c++) {
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target[c] = 0;
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for(int channel = 0; channel < 2; channel++) {
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divider_counter_[channel] ++;
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int divider_value = divider_counter_[channel] / (38 / CPUTicksPerAudioTick);
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int level = 0;
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switch(control_[channel]) {
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case 0x0: case 0xb: // constant 1
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level = 1;
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break;
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case 0x4: case 0x5: // div2 tone
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level = (divider_value / (divider_[channel]+1))&1;
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break;
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case 0xc: case 0xd: // div6 tone
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level = (divider_value / ((divider_[channel]+1)*3))&1;
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break;
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case 0x6: case 0xa: // div31 tone
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level = (divider_value / (divider_[channel]+1))%30 <= 18;
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break;
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case 0xe: // div93 tone
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level = (divider_value / ((divider_[channel]+1)*3))%30 <= 18;
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break;
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case 0x1: // 4-bit poly
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level = poly4_counter_[channel]&1;
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if(divider_value == divider_[channel]+1) {
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divider_counter_[channel] = 0;
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advance_poly4(channel);
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}
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break;
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case 0x2: // 4-bit poly div31
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level = poly4_counter_[channel]&1;
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if(divider_value%(30*(divider_[channel]+1)) == 18) {
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advance_poly4(channel);
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}
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break;
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case 0x3: // 5/4-bit poly
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level = output_state_[channel];
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if(divider_value == divider_[channel]+1) {
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if(poly5_counter_[channel]&1) {
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output_state_[channel] = poly4_counter_[channel]&1;
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advance_poly4(channel);
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}
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advance_poly5(channel);
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}
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break;
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case 0x7: case 0x9: // 5-bit poly
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level = poly5_counter_[channel]&1;
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if(divider_value == divider_[channel]+1) {
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divider_counter_[channel] = 0;
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advance_poly5(channel);
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}
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break;
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case 0xf: // 5-bit poly div6
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level = poly5_counter_[channel]&1;
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if(divider_value == (divider_[channel]+1)*3) {
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divider_counter_[channel] = 0;
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advance_poly5(channel);
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}
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break;
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case 0x8: // 9-bit poly
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level = poly9_counter_[channel]&1;
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if(divider_value == divider_[channel]+1) {
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divider_counter_[channel] = 0;
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advance_poly9(channel);
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}
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break;
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}
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target[c] += volume_[channel] * 1024 * level;
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}
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}
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}
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