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CLK/Storage/Tape/Formats/CommodoreTAP.cpp

94 lines
1.9 KiB
C++

//
// CommodoreTAP.cpp
// Clock Signal
//
// Created by Thomas Harte on 25/06/2016.
// Copyright © 2016 Thomas Harte. All rights reserved.
//
#include "CommodoreTAP.hpp"
#include <cstdio>
#include <cstring>
using namespace Storage::Tape;
CommodoreTAP::CommodoreTAP(const char *file_name) :
is_at_end_(false),
Storage::FileHolder(file_name)
{
if(!check_signature("C64-TAPE-RAW", 12))
throw ErrorNotCommodoreTAP;
// check the file version
int version = fgetc(file_);
switch(version)
{
case 0: updated_layout_ = false; break;
case 1: updated_layout_ = true; break;
default: throw ErrorNotCommodoreTAP;
}
// skip reserved bytes
fseek(file_, 3, SEEK_CUR);
// read file size
file_size_ = fgetc32le();
// set up for pulse output at the PAL clock rate, with each high and
// low being half of whatever length values will be read; pretend that
// a high pulse has just been distributed to imply that the next thing
// that needs to happen is a length check
current_pulse_.length.clock_rate = 985248 * 2;
current_pulse_.type = Pulse::High;
}
void CommodoreTAP::virtual_reset()
{
fseek(file_, 0x14, SEEK_SET);
current_pulse_.type = Pulse::High;
is_at_end_ = false;
}
bool CommodoreTAP::is_at_end()
{
return is_at_end_;
}
Storage::Tape::Tape::Pulse CommodoreTAP::virtual_get_next_pulse()
{
if(is_at_end_)
{
return current_pulse_;
}
if(current_pulse_.type == Pulse::High)
{
uint32_t next_length;
uint8_t next_byte = (uint8_t)fgetc(file_);
if(!updated_layout_ || next_byte > 0)
{
next_length = (uint32_t)next_byte << 3;
}
else
{
next_length = fgetc24le();
}
if(feof(file_))
{
is_at_end_ = true;
current_pulse_.length.length = current_pulse_.length.clock_rate;
current_pulse_.type = Pulse::Zero;
}
else
{
current_pulse_.length.length = next_length;
current_pulse_.type = Pulse::Low;
}
}
else
current_pulse_.type = Pulse::High;
return current_pulse_;
}