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168 lines
4.6 KiB
C++
168 lines
4.6 KiB
C++
//
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// Oric.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 06/11/2016.
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// Copyright 2016 Thomas Harte. All rights reserved.
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//
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#include "Oric.hpp"
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using namespace Storage::Tape::Oric;
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int Parser::get_next_byte(const std::shared_ptr<Storage::Tape::Tape> &tape, bool use_fast_encoding) {
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detection_mode_ = use_fast_encoding ? FastZero : SlowZero;
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cycle_length_ = 0.0f;
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int result = 0;
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int bit_count = 0;
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while(bit_count < 11 && !tape->is_at_end()) {
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SymbolType symbol = get_next_symbol(tape);
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if(!bit_count && symbol != SymbolType::Zero) continue;
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detection_mode_ = use_fast_encoding ? FastData : SlowData;
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result |= ((symbol == SymbolType::One) ? 1 : 0) << bit_count;
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bit_count++;
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}
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// TODO: check parity?
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return tape->is_at_end() ? -1 : ((result >> 1)&0xff);
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}
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bool Parser::sync_and_get_encoding_speed(const std::shared_ptr<Storage::Tape::Tape> &tape) {
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detection_mode_ = Sync;
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while(!tape->is_at_end()) {
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const SymbolType symbol = get_next_symbol(tape);
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switch(symbol) {
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case SymbolType::FoundSlow: return false;
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case SymbolType::FoundFast: return true;
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default: break;
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}
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}
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return false;
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}
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void Parser::process_pulse(const Storage::Tape::Tape::Pulse &pulse) {
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constexpr float maximum_short_length = 0.000512f;
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constexpr float maximum_medium_length = 0.000728f;
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constexpr float maximum_long_length = 0.001456f;
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const bool wave_is_high = pulse.type == Storage::Tape::Tape::Pulse::High;
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if(!wave_was_high_ && wave_is_high != wave_was_high_) {
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if(cycle_length_ < maximum_short_length) push_wave(WaveType::Short);
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else if(cycle_length_ < maximum_medium_length) push_wave(WaveType::Medium);
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else if(cycle_length_ < maximum_long_length) push_wave(WaveType::Long);
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else push_wave(WaveType::Unrecognised);
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cycle_length_ = 0.0f;
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}
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wave_was_high_ = wave_is_high;
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cycle_length_ += pulse.length.get<float>();
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}
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void Parser::inspect_waves(const std::vector<WaveType> &waves) {
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switch(detection_mode_) {
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case FastZero:
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if(waves.empty()) return;
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if(waves[0] == WaveType::Medium) {
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push_symbol(SymbolType::Zero, 1);
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return;
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}
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break;
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case FastData:
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if(waves.empty()) return;
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if(waves[0] == WaveType::Medium) {
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push_symbol(SymbolType::Zero, 1);
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return;
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}
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if(waves[0] == WaveType::Short) {
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push_symbol(SymbolType::One, 1);
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return;
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}
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break;
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case SlowZero:
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if(waves.size() < 4) return;
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if(waves[0] == WaveType::Long && waves[1] == WaveType::Long && waves[2] == WaveType::Long && waves[3] == WaveType::Long) {
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push_symbol(SymbolType::Zero, 4);
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return;
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}
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break;
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case SlowData:
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#define CHECK_RUN(length, type, symbol) \
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if(waves.size() >= length) {\
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std::size_t c;\
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for(c = 0; c < length; c++) if(waves[c] != type) break;\
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if(c == length) {\
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push_symbol(symbol, length);\
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return;\
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}\
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}
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CHECK_RUN(4, WaveType::Long, SymbolType::Zero);
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CHECK_RUN(8, WaveType::Short, SymbolType::One);
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#undef CHECK_RUN
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if(waves.size() < 16) return; // TODO, maybe: if there are any inconsistencies in the first 8, don't return
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break;
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case Sync: {
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// Sync is 0x16, either encoded fast or slow; i.e. 0 0110 1000 1
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const Pattern slow_sync[] = {
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{WaveType::Long, 8},
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{WaveType::Short, 16},
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{WaveType::Long, 4},
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{WaveType::Short, 8},
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{WaveType::Long, 12},
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{WaveType::Short, 8},
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{WaveType::Unrecognised}
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};
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const Pattern fast_sync[] = {
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{WaveType::Medium, 2},
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{WaveType::Short, 2},
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{WaveType::Medium, 1},
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{WaveType::Short, 1},
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{WaveType::Medium, 3},
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{WaveType::Short, 1},
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{WaveType::Unrecognised}
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};
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std::size_t slow_sync_matching_depth = pattern_matching_depth(waves, slow_sync);
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std::size_t fast_sync_matching_depth = pattern_matching_depth(waves, fast_sync);
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if(slow_sync_matching_depth == 52) {
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push_symbol(SymbolType::FoundSlow, 52);
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return;
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}
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if(fast_sync_matching_depth == 10) {
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push_symbol(SymbolType::FoundFast, 10);
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return;
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}
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if(slow_sync_matching_depth < waves.size() && fast_sync_matching_depth < waves.size()) {
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int least_depth = int(std::min(slow_sync_matching_depth, fast_sync_matching_depth));
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remove_waves(least_depth ? least_depth : 1);
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}
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return;
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}
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break;
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}
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remove_waves(1);
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}
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std::size_t Parser::pattern_matching_depth(const std::vector<WaveType> &waves, const Pattern *pattern) {
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std::size_t depth = 0;
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int pattern_depth = 0;
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while(depth < waves.size() && pattern->type != WaveType::Unrecognised) {
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if(waves[depth] != pattern->type) break;
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depth++;
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pattern_depth++;
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if(pattern_depth == pattern->count) {
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pattern_depth = 0;
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pattern++;
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}
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}
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return depth;
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}
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