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104 lines
2.6 KiB
C++
104 lines
2.6 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) : Tape(serialiser_), serialiser_(file_name) {}
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CommodoreTAP::Serialiser::Serialiser(const std::string &file_name) :
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file_(file_name, FileHolder::FileMode::Read)
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{
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const bool is_c64 = file_.check_signature("C64-TAPE-RAW");
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file_.seek(0, SEEK_SET);
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const bool is_c16 = file_.check_signature("C16-TAPE-RAW");
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if(!is_c64 && !is_c16) {
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throw ErrorNotCommodoreTAP;
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}
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type_ = is_c16 ? FileType::C16 : FileType::C64;
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// Get and check the file version.
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version_ = file_.get8();
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if(version_ > 2) {
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throw ErrorNotCommodoreTAP;
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}
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// Read clock rate-implying bytes.
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platform_ = Platform(file_.get8());
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video_ = VideoStandard(file_.get8());
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file_.seek(1, SEEK_CUR);
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// Read file size.
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file_size_ = file_.get32le();
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// Pick clock rate.
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current_pulse_.length.clock_rate = static_cast<unsigned int>(
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[&] {
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switch(platform_) {
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case Platform::Vic20: // It empirically seems like Vic-20 waves are counted with C64 timings?
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case Platform::C64: return video_ == VideoStandard::PAL ? 985'248 : 1'022'727;
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case Platform::C16: return video_ == VideoStandard::PAL ? 886'722 : 894'886;
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}
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}() * (double_clock() ? 2 : 1)
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);
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reset();
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}
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void CommodoreTAP::Serialiser::reset() {
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file_.seek(0x14, SEEK_SET);
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current_pulse_.type = Pulse::High; // Implies that the first posted wave will be ::Low.
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is_at_end_ = false;
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}
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bool CommodoreTAP::Serialiser::is_at_end() const {
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return is_at_end_;
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}
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Storage::Tape::Pulse CommodoreTAP::Serialiser::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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const auto read_next_length = [&]() -> bool {
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uint32_t next_length;
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const 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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return false;
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} else {
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current_pulse_.length.length = next_length;
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return true;
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}
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};
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if(half_waves()) {
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if(read_next_length()) {
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current_pulse_.type = current_pulse_.type == Pulse::High ? Pulse::Low : Pulse::High;
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}
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} else if(current_pulse_.type == Pulse::High) {
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if(read_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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