mirror of
https://github.com/hrydgard/ppsspp.git
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126 lines
4.0 KiB
C++
126 lines
4.0 KiB
C++
// Frame timing
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//
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// A frame on the main thread should look a bit like this:
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//
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// 1. -- Wait for the right time to start the frame (alternatively, see this is step 8).
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// 2. Sample inputs (on some platforms, this is done continouously during step 3)
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// 3. Run CPU
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// 4. Submit GPU commands (there's no reason to ever wait before this).
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// 5. -- Wait for the right time to present
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// 6. Send Present command
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// 7. Do other end-of-frame stuff
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//
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// To minimize latency, we should *maximize* 1 and *minimize* 5 (while still keeping some margin to soak up hitches).
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// Additionally, if too many completed frames have been buffered up, we need a feedback mechanism, so we can temporarily
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// artificially increase 1 in order to "catch the CPU up".
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//
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// There are some other things that can influence the frame timing:
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// * Unthrottling. If vsync is off or the backend can change present mode dynamically, we can simply disable all waits during unthrottle.
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// * Frame skipping. This gets complicated.
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// * The game not actually asking for flips, like in static loading screens
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#include "Common/Profiler/Profiler.h"
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#include "Common/Log.h"
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#include "Common/TimeUtil.h"
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#include "Core/RetroAchievements.h"
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#include "Core/CoreParameter.h"
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#include "Core/Core.h"
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#include "Core/Config.h"
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#include "Core/HW/Display.h"
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#include "Core/FrameTiming.h"
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FrameTiming g_frameTiming;
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void WaitUntil(double now, double timestamp) {
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#ifdef _WIN32
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while (time_now_d() < timestamp) {
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sleep_ms(1); // Sleep for 1ms on this thread
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}
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#else
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const double left = timestamp - now;
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if (left > 0.0) {
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usleep((long)(left * 1000000));
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}
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#endif
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}
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inline Draw::PresentMode GetBestImmediateMode(Draw::PresentMode supportedModes) {
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if (supportedModes & Draw::PresentMode::MAILBOX) {
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return Draw::PresentMode::MAILBOX;
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} else {
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return Draw::PresentMode::IMMEDIATE;
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}
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}
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void FrameTiming::Reset(Draw::DrawContext *draw) {
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if (g_Config.bVSync || !(draw->GetDeviceCaps().presentModesSupported & (Draw::PresentMode::MAILBOX | Draw::PresentMode::IMMEDIATE))) {
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presentMode = Draw::PresentMode::FIFO;
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presentInterval = 1;
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} else {
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presentMode = GetBestImmediateMode(draw->GetDeviceCaps().presentModesSupported);
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presentInterval = 0;
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}
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}
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void FrameTiming::DeferWaitUntil(double until, double *curTimePtr) {
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_dbg_assert_(until > 0.0);
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waitUntil_ = until;
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curTimePtr_ = curTimePtr;
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}
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void FrameTiming::PostSubmit() {
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if (waitUntil_ != 0.0) {
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WaitUntil(time_now_d(), waitUntil_);
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if (curTimePtr_) {
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*curTimePtr_ = waitUntil_;
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}
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waitUntil_ = 0.0;
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}
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}
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Draw::PresentMode ComputePresentMode(Draw::DrawContext *draw, int *interval) {
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Draw::PresentMode mode = Draw::PresentMode::FIFO;
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if (draw->GetDeviceCaps().presentModesSupported & (Draw::PresentMode::IMMEDIATE | Draw::PresentMode::MAILBOX)) {
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// Switch to immediate if desired and possible.
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bool wantInstant = false;
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if (!g_Config.bVSync) {
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wantInstant = true;
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}
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if (PSP_CoreParameter().fastForward) {
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wantInstant = true;
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}
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if (PSP_CoreParameter().fpsLimit != FPSLimit::NORMAL) {
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int limit;
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if (PSP_CoreParameter().fpsLimit == FPSLimit::CUSTOM1)
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limit = g_Config.iFpsLimit1;
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else if (PSP_CoreParameter().fpsLimit == FPSLimit::CUSTOM2)
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limit = g_Config.iFpsLimit2;
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else
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limit = PSP_CoreParameter().analogFpsLimit;
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// For an alternative speed that is a clean factor of 60, the user probably still wants vsync.
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// TODO: Should take the user's display refresh rate into account...
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if (limit == 0 || (limit >= 0 && limit != 15 && limit != 30 && limit != 60)) {
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wantInstant = true;
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}
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}
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if (wantInstant && g_Config.bVSync && !draw->GetDeviceCaps().presentInstantModeChange) {
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// If in vsync mode (which will be FIFO), and the backend can't switch immediately,
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// stick to FIFO.
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wantInstant = false;
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}
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// The outer if checks that instant modes are available.
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if (wantInstant) {
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mode = GetBestImmediateMode(draw->GetDeviceCaps().presentModesSupported);
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}
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}
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*interval = (mode == Draw::PresentMode::FIFO) ? 1 : 0;
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return mode;
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}
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