88 lines
1.8 KiB
C++
88 lines
1.8 KiB
C++
#include "std_chrono_throttle.hpp"
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#include <thread>
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using namespace std::chrono;
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void Throttle::set_frame_rate(double frame_rate)
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{
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max_frame_rate = frame_rate;
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frame_duration = 1.0 / max_frame_rate;
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frame_duration_us = microseconds(int64_t(frame_duration * 1000000.0));
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}
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microseconds Throttle::remaining()
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{
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auto now = time_point_cast<microseconds>(steady_clock::now());
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auto diff = (now - then);
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return frame_duration_us - diff;
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}
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#if defined(_WIN32)
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#define WIN32_LEAN_AND_MEAN
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#include <windows.h>
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void Throttle::wait_for_frame()
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{
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static HANDLE timer = nullptr;
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if (timer == nullptr)
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timer = CreateWaitableTimer(nullptr, true, nullptr);
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auto time_to_wait = remaining();
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if (time_to_wait < -frame_duration_us / 10)
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reset();
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if (time_to_wait.count() > 2000)
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{
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LARGE_INTEGER li;
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li.QuadPart = -(time_to_wait.count() - 2000) * 10;
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SetWaitableTimer(timer, &li, 0, nullptr, nullptr, false);
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WaitForSingleObject(timer, INFINITE);
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}
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time_to_wait = remaining();
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while (time_to_wait.count() > 0)
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{
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std::this_thread::yield();
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time_to_wait = remaining();
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}
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}
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#endif
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#if !defined(_WIN32)
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void Throttle::wait_for_frame()
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{
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auto time_to_wait = remaining();
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if (time_to_wait < -frame_duration_us / 10)
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reset();
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if (time_to_wait.count() > 1000)
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std::this_thread::sleep_for(time_to_wait - 1ms);
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time_to_wait = remaining();
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while (time_to_wait.count() > 0)
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{
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std::this_thread::yield();
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time_to_wait = remaining();
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}
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}
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#endif
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void Throttle::wait_for_frame_and_rebase_time()
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{
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wait_for_frame();
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advance();
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}
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void Throttle::advance()
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{
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then += frame_duration_us;
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}
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void Throttle::reset()
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{
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auto now = time_point_cast<microseconds>(steady_clock::now());
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then = now;
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}
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