mirror of
https://github.com/TomHarte/CLK.git
synced 2024-08-16 16:28:59 +00:00
121 lines
3.3 KiB
C++
121 lines
3.3 KiB
C++
//
|
|
// Shifter.cpp
|
|
// Clock Signal
|
|
//
|
|
// Created by Thomas Harte on 24/09/2017.
|
|
// Copyright © 2017 Thomas Harte. All rights reserved.
|
|
//
|
|
|
|
#include "Shifter.hpp"
|
|
#include "Constants.hpp"
|
|
|
|
using namespace Storage::Encodings::MFM;
|
|
|
|
Shifter::Shifter() : owned_crc_generator_(new NumberTheory::CRC16(0x1021, 0xffff)), crc_generator_(owned_crc_generator_.get()) {}
|
|
Shifter::Shifter(NumberTheory::CRC16 *crc_generator) : crc_generator_(crc_generator) {}
|
|
|
|
void Shifter::set_is_double_density(bool is_double_density) {
|
|
is_double_density_ = is_double_density;
|
|
if(!is_double_density) is_awaiting_marker_value_ = false;
|
|
}
|
|
|
|
void Shifter::set_should_obey_syncs(bool should_obey_syncs) {
|
|
should_obey_syncs_ = should_obey_syncs;
|
|
}
|
|
|
|
void Shifter::add_input_bit(int value) {
|
|
shift_register_ = (shift_register_ << 1) | static_cast<unsigned int>(value);
|
|
bits_since_token_++;
|
|
|
|
token_ = Token::None;
|
|
if(should_obey_syncs_) {
|
|
if(!is_double_density_) {
|
|
switch(shift_register_ & 0xffff) {
|
|
case Storage::Encodings::MFM::FMIndexAddressMark:
|
|
token_ = Token::Index;
|
|
crc_generator_->reset();
|
|
crc_generator_->add(Storage::Encodings::MFM::IndexAddressByte);
|
|
break;
|
|
case Storage::Encodings::MFM::FMIDAddressMark:
|
|
token_ = Token::ID;
|
|
crc_generator_->reset();
|
|
crc_generator_->add(Storage::Encodings::MFM::IDAddressByte);
|
|
break;
|
|
case Storage::Encodings::MFM::FMDataAddressMark:
|
|
token_ = Token::Data;
|
|
crc_generator_->reset();
|
|
crc_generator_->add(Storage::Encodings::MFM::DataAddressByte);
|
|
break;
|
|
case Storage::Encodings::MFM::FMDeletedDataAddressMark:
|
|
token_ = Token::DeletedData;
|
|
crc_generator_->reset();
|
|
crc_generator_->add(Storage::Encodings::MFM::DeletedDataAddressByte);
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
} else {
|
|
switch(shift_register_ & 0xffff) {
|
|
case Storage::Encodings::MFM::MFMIndexSync:
|
|
bits_since_token_ = 0;
|
|
is_awaiting_marker_value_ = true;
|
|
|
|
token_ = Token::Sync;
|
|
break;
|
|
case Storage::Encodings::MFM::MFMSync:
|
|
bits_since_token_ = 0;
|
|
is_awaiting_marker_value_ = true;
|
|
crc_generator_->set_value(Storage::Encodings::MFM::MFMPostSyncCRCValue);
|
|
|
|
token_ = Token::Sync;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
if(token_ != Token::None) {
|
|
bits_since_token_ = 0;
|
|
return;
|
|
}
|
|
}
|
|
|
|
if(bits_since_token_ == 16) {
|
|
token_ = Token::Byte;
|
|
bits_since_token_ = 0;
|
|
|
|
if(is_awaiting_marker_value_ && is_double_density_) {
|
|
is_awaiting_marker_value_ = false;
|
|
switch(get_byte()) {
|
|
case Storage::Encodings::MFM::IndexAddressByte:
|
|
token_ = Token::Index;
|
|
break;
|
|
case Storage::Encodings::MFM::IDAddressByte:
|
|
token_ = Token::ID;
|
|
break;
|
|
case Storage::Encodings::MFM::DataAddressByte:
|
|
token_ = Token::Data;
|
|
break;
|
|
case Storage::Encodings::MFM::DeletedDataAddressByte:
|
|
token_ = Token::DeletedData;
|
|
break;
|
|
default: break;
|
|
}
|
|
}
|
|
|
|
crc_generator_->add(get_byte());
|
|
}
|
|
}
|
|
|
|
uint8_t Shifter::get_byte() const {
|
|
return static_cast<uint8_t>(
|
|
((shift_register_ & 0x0001) >> 0) |
|
|
((shift_register_ & 0x0004) >> 1) |
|
|
((shift_register_ & 0x0010) >> 2) |
|
|
((shift_register_ & 0x0040) >> 3) |
|
|
((shift_register_ & 0x0100) >> 4) |
|
|
((shift_register_ & 0x0400) >> 5) |
|
|
((shift_register_ & 0x1000) >> 6) |
|
|
((shift_register_ & 0x4000) >> 7));
|
|
}
|