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95 lines
2.4 KiB
C++
95 lines
2.4 KiB
C++
//
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// Acorn.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 06/11/2016.
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// Copyright 2016 Thomas Harte. All rights reserved.
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//
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#include "Acorn.hpp"
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using namespace Storage::Tape::Acorn;
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namespace {
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const int PLLClockRate = 1920000;
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}
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Parser::Parser(): crc_(0x1021) {
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shifter_.set_delegate(this);
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}
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int Parser::get_next_bit(const std::shared_ptr<Storage::Tape::Tape> &tape) {
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SymbolType symbol = get_next_symbol(tape);
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return (symbol == SymbolType::One) ? 1 : 0;
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}
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int Parser::get_next_byte(const std::shared_ptr<Storage::Tape::Tape> &tape) {
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int value = 0;
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int c = 8;
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if(get_next_bit(tape)) {
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set_error_flag();
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return -1;
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}
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while(c--) {
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value = (value >> 1) | (get_next_bit(tape) << 7);
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}
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if(!get_next_bit(tape)) {
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set_error_flag();
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return -1;
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}
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crc_.add(static_cast<uint8_t>(value));
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return value;
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}
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unsigned int Parser::get_next_short(const std::shared_ptr<Storage::Tape::Tape> &tape) {
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unsigned int result = static_cast<unsigned int>(get_next_byte(tape));
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result |= static_cast<unsigned int>(get_next_byte(tape)) << 8;
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return result;
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}
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unsigned int Parser::get_next_word(const std::shared_ptr<Storage::Tape::Tape> &tape) {
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unsigned int result = get_next_short(tape);
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result |= get_next_short(tape) << 8;
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return result;
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}
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void Parser::reset_crc() { crc_.reset(); }
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uint16_t Parser::get_crc() { return crc_.get_value(); }
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void Parser::acorn_shifter_output_bit(int value) {
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push_symbol(value ? SymbolType::One : SymbolType::Zero);
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}
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void Parser::process_pulse(const Storage::Tape::Tape::Pulse &pulse) {
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shifter_.process_pulse(pulse);
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}
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Shifter::Shifter() :
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pll_(PLLClockRate / 4800, 15),
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was_high_(false),
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input_pattern_(0),
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input_bit_counter_(0),
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delegate_(nullptr) {
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pll_.set_delegate(this);
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}
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void Shifter::process_pulse(const Storage::Tape::Tape::Pulse &pulse) {
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pll_.run_for(Cycles(static_cast<int>(static_cast<float>(PLLClockRate) * pulse.length.get<float>())));
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bool is_high = pulse.type == Storage::Tape::Tape::Pulse::High;
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if(is_high != was_high_) {
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pll_.add_pulse();
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}
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was_high_ = is_high;
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}
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void Shifter::digital_phase_locked_loop_output_bit(int value) {
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input_pattern_ = ((input_pattern_ << 1) | static_cast<unsigned int>(value)) & 0xf;
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switch(input_pattern_) {
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case 0x5: delegate_->acorn_shifter_output_bit(0); input_pattern_ = 0; break;
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case 0xf: delegate_->acorn_shifter_output_bit(1); input_pattern_ = 0; break;
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default: break;
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}
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}
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