1 /* ScummVM - Graphic Adventure Engine
2 *
3 * ScummVM is the legal property of its developers, whose names
4 * are too numerous to list here. Please refer to the COPYRIGHT
5 * file distributed with this source distribution.
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version 2
10 * of the License, or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
20 *
21 */
22
23 #include "bladerunner/framelimiter.h"
24
25 #include "bladerunner/bladerunner.h"
26 #include "bladerunner/time.h"
27
28 #include "common/debug.h"
29 #include "common/system.h"
30
31 namespace BladeRunner {
32
Framelimiter(BladeRunnerEngine * vm,uint fps)33 Framelimiter::Framelimiter(BladeRunnerEngine *vm, uint fps) {
34 _vm = vm;
35
36 reset();
37
38 if (fps > 0) {
39 _enabled = true;
40 _speedLimitMs = 1000 / fps;
41 } else {
42 _enabled = false;
43 }
44
45 _timeFrameStart = _vm->_time->currentSystem();
46 }
47
wait()48 void Framelimiter::wait() {
49 // TODO: when vsync will be supported, use it
50
51 if (!_enabled) {
52 return;
53 }
54
55 uint32 timeNow = _vm->_time->currentSystem();
56 uint32 frameDuration = timeNow - _timeFrameStart;
57 if (frameDuration < _speedLimitMs) {
58 uint32 waittime = _speedLimitMs - frameDuration;
59 if (_vm->_noDelayMillisFramelimiter) {
60 while (_vm->_time->currentSystem() - timeNow < waittime) { }
61 } else {
62 _vm->_system->delayMillis(waittime);
63 }
64 timeNow += waittime;
65 }
66 // debug("frametime %i ms", timeNow - _timeFrameStart);
67 // using _vm->_time->currentSystem() here is slower and causes some shutters
68 _timeFrameStart = timeNow;
69 }
70
reset()71 void Framelimiter::reset() {
72 _timeFrameStart = 0u;
73 }
74
75 } // End of namespace BladeRunner
76