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175 lines
4.5 KiB
C++
175 lines
4.5 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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{
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_detection_mode = use_fast_encoding ? FastData : SlowData;
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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 < 10 && !tape->is_at_end())
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{
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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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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&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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{
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_detection_mode = Sync;
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while(!tape->is_at_end())
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{
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SymbolType symbol = get_next_symbol(tape);
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switch(symbol)
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{
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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(Storage::Tape::Tape::Pulse pulse)
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{
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const float length_threshold = 0.0003125f;
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bool wave_is_high = pulse.type == Storage::Tape::Tape::Pulse::High;
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bool did_change = (wave_is_high != _wave_was_high && _cycle_length > 0.0f);
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_wave_was_high = wave_is_high;
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if(did_change)
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{
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if(_cycle_length > 2.0 * length_threshold) push_wave(WaveType::Unrecognised);
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else push_wave(_cycle_length < length_threshold ? WaveType::Short : WaveType::Long);
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_cycle_length = 0.0f;
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}
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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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{
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switch(_detection_mode)
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{
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case FastData:
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if(waves.size() < 2) return;
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if(waves[0] == WaveType::Short && waves[1] != WaveType::Unrecognised)
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{
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push_symbol((waves[1] == WaveType::Long) ? SymbolType::Zero : SymbolType::One, 2);
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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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{\
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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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{\
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push_symbol(symbol, 8);\
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return;\
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}\
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}
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CHECK_RUN(8, WaveType::Long, SymbolType::Zero);
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CHECK_RUN(16, 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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{
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// Sync is 0x16, either encoded fast or slow; i.e. 0 0110 1000 1
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// So, fast: [short, long]*2, [short, short]*2, [short, long], [short, short], [short, long]*3, [short, short] = 20
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// [short, short] = 1; [short, long] = 0
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// Slow: long*16, short*32, long*8, short*16, long*24, short*16 = 112
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Pattern slow_sync[] =
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{
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{.type = WaveType::Long, 16},
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{.type = WaveType::Short, 32},
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{.type = WaveType::Long, 8},
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{.type = WaveType::Short, 16},
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{.type = WaveType::Long, 24},
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{.type = WaveType::Short, 16},
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{.type = WaveType::Unrecognised}
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};
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Pattern fast_sync[] =
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{
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{.type = WaveType::Short, 1},
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{.type = WaveType::Long, 1},
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{.type = WaveType::Short, 1},
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{.type = WaveType::Long, 1},
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{.type = WaveType::Short, 5},
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{.type = WaveType::Long, 1},
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{.type = WaveType::Short, 3},
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{.type = WaveType::Long, 1},
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{.type = WaveType::Short, 1},
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{.type = WaveType::Long, 1},
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{.type = WaveType::Short, 1},
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{.type = WaveType::Long, 1},
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{.type = WaveType::Short, 2},
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{.type = WaveType::Unrecognised}
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};
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size_t slow_sync_matching_depth = pattern_matching_depth(waves, slow_sync);
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size_t fast_sync_matching_depth = pattern_matching_depth(waves, fast_sync);
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if(slow_sync_matching_depth == 112)
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{
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push_symbol(SymbolType::FoundSlow, 112);
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return;
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}
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if(fast_sync_matching_depth == 20)
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{
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push_symbol(SymbolType::FoundFast, 20);
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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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{
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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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size_t Parser::pattern_matching_depth(const std::vector<WaveType> &waves, Pattern *pattern)
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{
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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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{
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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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{
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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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