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Widened tolerances and ensured zero bits aren't prematurely discarded.

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This commit is contained in:
Thomas Harte 2017-06-07 17:50:03 -04:00
parent 8aab9acc10
commit c47128f433
1 changed files with 16 additions and 7 deletions
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23
Storage/Tape/Parsers/ZX8081.cpp
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@ -24,16 +24,18 @@ void Parser::process_pulse(Storage::Tape::Tape::Pulse pulse) {
float pulse_time = pulse_time_.get_float();
pulse_time_.set_zero();
if(pulse_time > expected_gap_length * 1.1f) {
if(pulse_time > expected_gap_length * 1.25f) {
push_wave(WaveType::LongGap);
}
else if(pulse_time >= expected_pulse_length * 0.9f) {
else if(pulse_time > expected_pulse_length * 1.25f) {
push_wave(WaveType::Gap);
}
else if(pulse_time >= expected_pulse_length * 0.9f && pulse_time <= expected_pulse_length * 1.1f) {
else if(pulse_time >= expected_pulse_length * 0.75f && pulse_time <= expected_pulse_length * 1.25f) {
push_wave(WaveType::Pulse);
}
else push_wave(WaveType::Unrecognised);
else {
push_wave(WaveType::Unrecognised);
}
}
void Parser::inspect_waves(const std::vector<WaveType> &waves) {
@ -52,12 +54,19 @@ void Parser::inspect_waves(const std::vector<WaveType> &waves) {
// If those pulses were followed by a gap then they might be
// a recognised symbol.
if(number_of_pulses < waves.size() &&
if(number_of_pulses > 17 || number_of_pulses < 7) {
push_symbol(SymbolType::Unrecognised, 1);
}
else if(number_of_pulses < waves.size() &&
(waves[number_of_pulses] == WaveType::LongGap || waves[number_of_pulses] == WaveType::Gap)) {
// A 1 is 18 up/down waves, a 0 is 8. But the final down will be indistinguishable from
// the gap that follows the bit due to the simplified "high is high, everything else is low"
// logic applied to pulse detection. So those two things will merge. Meaning we're looking for
// 17 and/or 7 pulses.
int gaps_to_swallow = (waves[number_of_pulses] == WaveType::Gap) ? 1 : 0;
switch(number_of_pulses) {
case 18: push_symbol(SymbolType::One, 18 + gaps_to_swallow); break;
case 8: push_symbol(SymbolType::Zero, 8 + gaps_to_swallow); break;
case 17: push_symbol(SymbolType::One, 17 + gaps_to_swallow); break;
case 7: push_symbol(SymbolType::Zero, 7 + gaps_to_swallow); break;
default: push_symbol(SymbolType::Unrecognised, 1); break;
}
}