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CLK/Storage/Tape/Formats/TapeUEF.cpp

212 lines
4.3 KiB
C++

//
// TapeUEF.cpp
// Clock Signal
//
// Created by Thomas Harte on 18/01/2016.
// Copyright © 2016 Thomas Harte. All rights reserved.
//
#include "TapeUEF.hpp"
#include <string.h>
Storage::UEF::UEF(const char *file_name) :
_chunk_id(0), _chunk_length(0), _chunk_position(0),
_time_base(1200)
{
_file = gzopen(file_name, "rb");
char identifier[10];
int bytes_read = gzread(_file, identifier, 10);
if(bytes_read < 10 || strcmp(identifier, "UEF File!"))
{
throw ErrorNotUEF;
}
int minor, major;
minor = gzgetc(_file);
major = gzgetc(_file);
if(major > 0 || minor > 10 || major < 0 || minor < 0)
{
throw ErrorNotUEF;
}
find_next_tape_chunk();
}
Storage::UEF::~UEF()
{
gzclose(_file);
}
void Storage::UEF::reset()
{
gzseek(_file, 12, SEEK_SET);
}
Storage::Tape::Pulse Storage::UEF::get_next_pulse()
{
Pulse next_pulse;
if(!_bit_position && chunk_is_finished())
{
find_next_tape_chunk();
}
switch(_chunk_id)
{
case 0x0100: case 0x0102:
{
// In the ordinary ("1200 baud") data encoding format,
// a zero bit is encoded as one complete cycle at the base frequency.
// A one bit is two complete cycles at twice the base frequency.
if(!_bit_position)
{
_current_bit = get_next_bit();
}
next_pulse.type = (_bit_position&1) ? Pulse::High : Pulse::Low;
next_pulse.length.length = _current_bit ? 1 : 2;
next_pulse.length.clock_rate = _time_base * 4;
_bit_position = (_bit_position+1)&(_current_bit ? 3 : 1);
} break;
case 0x0110:
next_pulse.type = (_bit_position&1) ? Pulse::High : Pulse::Low;
next_pulse.length.length = 1;
next_pulse.length.clock_rate = _time_base * 4;
_bit_position ^= 1;
if(!_bit_position) _chunk_position++;
break;
case 0x0112:
case 0x0116:
next_pulse.type = Pulse::Zero;
next_pulse.length = _chunk_duration;
_chunk_position++;
break;
}
return next_pulse;
}
void Storage::UEF::find_next_tape_chunk()
{
int reset_count = 0;
_chunk_position = 0;
_bit_position = 0;
while(1)
{
// read chunk ID
_chunk_id = (uint16_t)gzgetc(_file);
_chunk_id |= (uint16_t)(gzgetc(_file) << 8);
_chunk_length = (uint32_t)(gzgetc(_file) << 0);
_chunk_length |= (uint32_t)(gzgetc(_file) << 8);
_chunk_length |= (uint32_t)(gzgetc(_file) << 16);
_chunk_length |= (uint32_t)(gzgetc(_file) << 24);
if(gzeof(_file))
{
reset_count++;
if(reset_count == 2) break;
reset();
continue;
}
switch(_chunk_id)
{
case 0x0100: case 0x0102: // implicit and explicit bit patterns
return;
case 0x0112:
_chunk_duration.length = (uint16_t)gzgetc(_file);
_chunk_duration.length |= (uint16_t)(gzgetc(_file) << 8);
_chunk_duration.clock_rate = _time_base;
return;
case 0x0116: // gaps
return;
case 0x0110: // carrier tone
_chunk_duration.length = (uint16_t)gzgetc(_file);
_chunk_duration.length |= (uint16_t)(gzgetc(_file) << 8);
gzseek(_file, _chunk_length - 2, SEEK_CUR);
return;
case 0x0111: // carrier tone with dummy byte
// TODO: read lengths
return;
case 0x0114: // security cycles
// TODO: read number, Ps and Ws
break;
case 0x113: // change of base rate
break;
default:
gzseek(_file, _chunk_length, SEEK_CUR);
break;
}
}
}
bool Storage::UEF::chunk_is_finished()
{
switch(_chunk_id)
{
case 0x0100: return (_chunk_position / 10) == _chunk_length;
case 0x0102: return (_chunk_position / 8) == _chunk_length;
case 0x0110: return _chunk_position == _chunk_duration.length;
case 0x0112:
case 0x0116: return _chunk_position ? true : false;
default: return true;
}
}
bool Storage::UEF::get_next_bit()
{
switch(_chunk_id)
{
case 0x0100:
{
uint32_t bit_position = _chunk_position%10;
_chunk_position++;
if(!bit_position)
{
_current_byte = (uint8_t)gzgetc(_file);
}
if(bit_position == 0) return false;
if(bit_position == 9) return true;
bool result = (_current_byte&1) ? true : false;
_current_byte >>= 1;
return result;
}
break;
case 0x0102:
{
uint32_t bit_position = _chunk_position%8;
_chunk_position++;
if(!bit_position)
{
_current_byte = (uint8_t)gzgetc(_file);
}
bool result = (_current_byte&1) ? true : false;
_current_byte >>= 1;
return result;
}
break;
case 0x0110:
_chunk_position++;
return true;
default: return true;
}
}