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80 lines
1.8 KiB
C++
80 lines
1.8 KiB
C++
//
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// CommodoreTAP.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 25/06/2016.
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// Copyright 2016 Thomas Harte. All rights reserved.
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//
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#include "CommodoreTAP.hpp"
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#include <cstdio>
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#include <cstring>
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using namespace Storage::Tape;
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CommodoreTAP::CommodoreTAP(const std::string &file_name) :
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file_(file_name)
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{
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if(!file_.check_signature("C64-TAPE-RAW"))
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throw ErrorNotCommodoreTAP;
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// check the file version
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switch(file_.get8()) {
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case 0: updated_layout_ = false; break;
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case 1: updated_layout_ = true; break;
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default: throw ErrorNotCommodoreTAP;
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}
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// skip reserved bytes
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file_.seek(3, SEEK_CUR);
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// read file size
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file_size_ = file_.get32le();
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// set up for pulse output at the PAL clock rate, with each high and
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// low being half of whatever length values will be read; pretend that
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// a high pulse has just been distributed to imply that the next thing
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// that needs to happen is a length check
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current_pulse_.length.clock_rate = 985248 * 2;
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current_pulse_.type = Pulse::High;
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}
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void CommodoreTAP::virtual_reset() {
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file_.seek(0x14, SEEK_SET);
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current_pulse_.type = Pulse::High;
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is_at_end_ = false;
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}
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bool CommodoreTAP::is_at_end() {
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return is_at_end_;
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}
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Storage::Tape::Tape::Pulse CommodoreTAP::virtual_get_next_pulse() {
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if(is_at_end_) {
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return current_pulse_;
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}
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if(current_pulse_.type == Pulse::High) {
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uint32_t next_length;
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uint8_t next_byte = file_.get8();
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if(!updated_layout_ || next_byte > 0) {
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next_length = uint32_t(next_byte) << 3;
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} else {
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next_length = file_.get24le();
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}
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if(file_.eof()) {
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is_at_end_ = true;
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current_pulse_.length.length = current_pulse_.length.clock_rate;
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current_pulse_.type = Pulse::Zero;
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} else {
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current_pulse_.length.length = next_length;
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current_pulse_.type = Pulse::Low;
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}
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} else {
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current_pulse_.type = Pulse::High;
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}
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return current_pulse_;
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}
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