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CLK/Machines/Electron/Tape.cpp

91 lines
2.5 KiB
C++

//
// Tape.cpp
// Clock Signal
//
// Created by Thomas Harte on 03/12/2016.
// Copyright 2016 Thomas Harte. All rights reserved.
//
#include "Tape.hpp"
using namespace Electron;
Tape::Tape() : TapePlayer(2000000) {
shifter_.set_delegate(this);
}
void Tape::push_tape_bit(uint16_t bit) {
data_register_ = static_cast<uint16_t>((data_register_ >> 1) | (bit << 10));
if(input_.minimum_bits_until_full) input_.minimum_bits_until_full--;
if(input_.minimum_bits_until_full == 8) interrupt_status_ &= ~Interrupt::ReceiveDataFull;
if(!input_.minimum_bits_until_full) {
if((data_register_&0x3) == 0x1) {
interrupt_status_ |= Interrupt::ReceiveDataFull;
if(is_in_input_mode_) input_.minimum_bits_until_full = 9;
}
}
if(output_.bits_remaining_until_empty) output_.bits_remaining_until_empty--;
if(!output_.bits_remaining_until_empty) interrupt_status_ |= Interrupt::TransmitDataEmpty;
if(data_register_ == 0x3ff) interrupt_status_ |= Interrupt::HighToneDetect;
else interrupt_status_ &= ~Interrupt::HighToneDetect;
evaluate_interrupts();
}
void Tape::evaluate_interrupts() {
if(last_posted_interrupt_status_ != interrupt_status_) {
last_posted_interrupt_status_ = interrupt_status_;
if(delegate_) delegate_->tape_did_change_interrupt_status(this);
}
}
void Tape::clear_interrupts(uint8_t interrupts) {
interrupt_status_ &= ~interrupts;
evaluate_interrupts();
}
void Tape::set_is_in_input_mode(bool is_in_input_mode) {
is_in_input_mode_ = is_in_input_mode;
}
void Tape::set_counter(uint8_t value) {
output_.cycles_into_pulse = 0;
output_.bits_remaining_until_empty = 0;
}
void Tape::set_data_register(uint8_t value) {
data_register_ = static_cast<uint16_t>((value << 2) | 1);
output_.bits_remaining_until_empty = 9;
}
uint8_t Tape::get_data_register() {
return static_cast<uint8_t>(data_register_ >> 2);
}
void Tape::process_input_pulse(const Storage::Tape::Tape::Pulse &pulse) {
shifter_.process_pulse(pulse);
}
void Tape::acorn_shifter_output_bit(int value) {
push_tape_bit(static_cast<uint16_t>(value));
}
void Tape::run_for(const Cycles cycles) {
if(is_enabled_) {
if(is_in_input_mode_) {
if(is_running_) {
TapePlayer::run_for(cycles);
}
} else {
output_.cycles_into_pulse += static_cast<unsigned int>(cycles.as_integral());
while(output_.cycles_into_pulse > 1664) { // 1664 = the closest you can get to 1200 baud if you're looking for something
output_.cycles_into_pulse -= 1664; // that divides the 125,000Hz clock that the sound divider runs off.
push_tape_bit(1);
}
}
}
}