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