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CLK/Storage/Tape/Parsers/Acorn.cpp

95 lines
2.4 KiB
C++

//
// Acorn.cpp
// Clock Signal
//
// Created by Thomas Harte on 06/11/2016.
// Copyright © 2016 Thomas Harte. All rights reserved.
//
#include "Acorn.hpp"
using namespace Storage::Tape::Acorn;
namespace {
const int PLLClockRate = 1920000;
}
Parser::Parser() : crc_(0x1021, 0x0000) {
shifter_.set_delegate(this);
}
int Parser::get_next_bit(const std::shared_ptr<Storage::Tape::Tape> &tape) {
SymbolType symbol = get_next_symbol(tape);
return (symbol == SymbolType::One) ? 1 : 0;
}
int Parser::get_next_byte(const std::shared_ptr<Storage::Tape::Tape> &tape) {
int value = 0;
int c = 8;
if(get_next_bit(tape)) {
set_error_flag();
return -1;
}
while(c--) {
value = (value >> 1) | (get_next_bit(tape) << 7);
}
if(!get_next_bit(tape)) {
set_error_flag();
return -1;
}
crc_.add(static_cast<uint8_t>(value));
return value;
}
unsigned int Parser::get_next_short(const std::shared_ptr<Storage::Tape::Tape> &tape) {
unsigned int result = static_cast<unsigned int>(get_next_byte(tape));
result |= static_cast<unsigned int>(get_next_byte(tape)) << 8;
return result;
}
unsigned int Parser::get_next_word(const std::shared_ptr<Storage::Tape::Tape> &tape) {
unsigned int result = get_next_short(tape);
result |= get_next_short(tape) << 8;
return result;
}
void Parser::reset_crc() { crc_.reset(); }
uint16_t Parser::get_crc() { return crc_.get_value(); }
void Parser::acorn_shifter_output_bit(int value) {
push_symbol(value ? SymbolType::One : SymbolType::Zero);
}
void Parser::process_pulse(const Storage::Tape::Tape::Pulse &pulse) {
shifter_.process_pulse(pulse);
}
Shifter::Shifter() :
pll_(PLLClockRate / 4800, 15),
was_high_(false),
input_pattern_(0),
input_bit_counter_(0),
delegate_(nullptr) {
pll_.set_delegate(this);
}
void Shifter::process_pulse(const Storage::Tape::Tape::Pulse &pulse) {
pll_.run_for(Cycles(static_cast<int>(static_cast<float>(PLLClockRate) * pulse.length.get_float())));
bool is_high = pulse.type == Storage::Tape::Tape::Pulse::High;
if(is_high != was_high_) {
pll_.add_pulse();
}
was_high_ = is_high;
}
void Shifter::digital_phase_locked_loop_output_bit(int value) {
input_pattern_ = ((input_pattern_ << 1) | static_cast<unsigned int>(value)) & 0xf;
switch(input_pattern_) {
case 0x5: delegate_->acorn_shifter_output_bit(0); input_pattern_ = 0; break;
case 0xf: delegate_->acorn_shifter_output_bit(1); input_pattern_ = 0; break;
default: break;
}
}