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https://github.com/libretro/scummvm.git
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5f29c6b523
This was not correct, and could cause endless frame skipping if SetGameSpeed() is called repeatedly in game script. From upstream 690f08b8468dd61ae570c7480098708ba6dc669f
100 lines
2.9 KiB
C++
100 lines
2.9 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "ags/lib/std/thread.h"
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#include "ags/engine/ac/timer.h"
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#include "ags/shared/core/platform.h"
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#include "ags/engine/ac/sys_events.h"
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#include "ags/engine/platform/base/ags_platform_driver.h"
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#include "ags/ags.h"
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#include "ags/globals.h"
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namespace AGS3 {
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namespace {
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const auto MAXIMUM_FALL_BEHIND = 3; // number of full frames
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}
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std::chrono::microseconds GetFrameDuration() {
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if (_G(framerate_maxed)) {
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return std::chrono::microseconds(0);
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}
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return _G(tick_duration);
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}
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int setTimerFps(int new_fps) {
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int old_fps = _G(framerate);
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_G(tick_duration) = std::chrono::microseconds(1000000LL / new_fps);
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_G(framerate) = new_fps;
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_G(framerate_maxed) = new_fps >= 1000;
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// Update next frame time
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_G(next_frame_timestamp) = _G(last_tick_time) + _G(tick_duration);
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return old_fps;
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}
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bool isTimerFpsMaxed() {
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return _G(framerate_maxed);
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}
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void WaitForNextFrame() {
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const auto now = AGS_Clock::now();
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const auto frameDuration = GetFrameDuration();
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// early exit if we're trying to maximise framerate
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if (frameDuration <= std::chrono::milliseconds::zero()) {
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_G(last_tick_time) = _G(next_frame_timestamp);
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_G(next_frame_timestamp) = now;
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// suspend while the game is being switched out
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while (_G(game_update_suspend) && !_G(want_exit) && !_G(abort_engine)) {
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sys_evt_process_pending();
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_G(platform)->YieldCPU();
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}
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return;
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}
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// jump ahead if we're lagging
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if (_G(next_frame_timestamp) < (now - MAXIMUM_FALL_BEHIND * frameDuration)) {
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_G(next_frame_timestamp) = now;
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}
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if (_G(next_frame_timestamp) > now) {
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auto frame_time_remaining = _G(next_frame_timestamp) - now;
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std::this_thread::sleep_for(frame_time_remaining);
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}
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_G(last_tick_time) = _G(next_frame_timestamp);
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_G(next_frame_timestamp) += frameDuration;
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// suspend while the game is being switched out
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while (_G(game_update_suspend) && !_G(want_exit) && !_G(abort_engine)) {
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sys_evt_process_pending();
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_G(platform)->YieldCPU();
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}
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}
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void skipMissedTicks() {
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_G(last_tick_time) = AGS_Clock::now();
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_G(next_frame_timestamp) = AGS_Clock::now();
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}
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} // namespace AGS3
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