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Experimentally switches to doubles for TimedEventLoop time tracking.

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This commit is contained in:
Thomas Harte 2018-04-30 22:07:17 -04:00
parent b32538f3c8
commit dbd9282efc
2 changed files with 13 additions and 49 deletions
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60
Storage/TimedEventLoop.cpp
View File

@ -11,6 +11,7 @@
#include <algorithm>
#include <cassert>
#include <cmath>
using namespace Storage;
@ -54,7 +55,7 @@ unsigned int TimedEventLoop::get_input_clock_rate() {
}
void TimedEventLoop::reset_timer() {
subcycles_until_event_.set_zero();
subcycles_until_event_ = 0.0;
cycles_until_event_ = 0;
}
@ -63,59 +64,22 @@ void TimedEventLoop::jump_to_next_event() {
process_next_event();
}
char text[256];
void TimedEventLoop::set_next_event_time_interval(Time interval) {
// Calculate [interval]*[input clock rate] + [subcycles until this event]
// = interval.numerator * input clock / interval.denominator + subcycles.numerator / subcycles.denominator
// = (interval.numerator * input clock * subcycles.denominator + subcycles.numerator * interval.denominator) / (interval.denominator * subcycles.denominator)
int64_t denominator = static_cast<int64_t>(interval.clock_rate) * static_cast<int64_t>(subcycles_until_event_.clock_rate);
int64_t numerator =
static_cast<int64_t>(subcycles_until_event_.clock_rate) * static_cast<int64_t>(input_clock_rate_) * static_cast<int64_t>(interval.length) +
static_cast<int64_t>(interval.clock_rate) * static_cast<int64_t>(subcycles_until_event_.length);
// Simplify if necessary: try just simplifying the interval and recalculating; if that doesn't
// work then try simplifying the whole thing.
if(numerator < 0 || denominator < 0 || denominator > std::numeric_limits<int>::max()) {
interval.simplify();
denominator = static_cast<int64_t>(interval.clock_rate) * static_cast<int64_t>(subcycles_until_event_.clock_rate);
numerator =
static_cast<int64_t>(subcycles_until_event_.clock_rate) * static_cast<int64_t>(input_clock_rate_) * static_cast<int64_t>(interval.length) +
static_cast<int64_t>(interval.clock_rate) * static_cast<int64_t>(subcycles_until_event_.length);
}
if(numerator < 0 || denominator < 0 || denominator > std::numeric_limits<int>::max()) {
int64_t common_divisor = NumberTheory::greatest_common_divisor(numerator % denominator, denominator);
denominator /= common_divisor;
numerator /= common_divisor;
}
// If even that doesn't work then reduce precision.
if(numerator < 0 || denominator < 0 || denominator > std::numeric_limits<int>::max()) {
// printf(".");
const double double_interval = interval.get<double>();
const double double_subcycles_remaining = subcycles_until_event_.get<double>();
const double output = double_interval * static_cast<double>(input_clock_rate_) + double_subcycles_remaining;
if(output < 1.0) {
denominator = std::numeric_limits<int>::max();
numerator = static_cast<int>(denominator * output);
} else {
numerator = std::numeric_limits<int>::max();
denominator = static_cast<int>(numerator / output);
}
}
double double_interval = interval.get<double>() * static_cast<double>(input_clock_rate_) + subcycles_until_event_;
// So this event will fire in the integral number of cycles from now, putting us at the remainder
// number of subcycles
const int addition = static_cast<int>(numerator / denominator);
assert(cycles_until_event_ == 0);
assert(addition >= 0);
if(addition < 0) {
assert(false);
}
const int addition = static_cast<int>(double_interval);
cycles_until_event_ += addition;
subcycles_until_event_.length = static_cast<unsigned int>(numerator % denominator);
subcycles_until_event_.clock_rate = static_cast<unsigned int>(denominator);
subcycles_until_event_.simplify();
subcycles_until_event_ = fmod(double_interval, 1.0);
assert(cycles_until_event_ >= 0);
assert(subcycles_until_event_ >= 0.0);
sprintf(text, " + %0.8f -> %d / %0.4f", interval.get<double>(), cycles_until_event_, subcycles_until_event_);
}
Time TimedEventLoop::get_time_into_next_event() {

2
Storage/TimedEventLoop.hpp
View File

@ -102,7 +102,7 @@ namespace Storage {
private:
unsigned int input_clock_rate_ = 0;
int cycles_until_event_ = 0;
Time subcycles_until_event_;
double subcycles_until_event_ = 0.0;
};
}