Atlas - SDL_systimer.c
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1/*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2018 Sam Lantinga <[email protected]>
4
5  This software is provided 'as-is', without any express or implied
6  warranty.  In no event will the authors be held liable for any damages
7  arising from the use of this software.
8
9  Permission is granted to anyone to use this software for any purpose,
10  including commercial applications, and to alter it and redistribute it
11  freely, subject to the following restrictions:
12
13  1. The origin of this software must not be misrepresented; you must not
14     claim that you wrote the original software. If you use this software
15     in a product, an acknowledgment in the product documentation would be
16     appreciated but is not required.
17  2. Altered source versions must be plainly marked as such, and must not be
18     misrepresented as being the original software.
19  3. This notice may not be removed or altered from any source distribution.
20*/
21#include "../../SDL_internal.h"
22
23#ifdef SDL_TIMER_WINDOWS
24
25#include "../../core/windows/SDL_windows.h"
26#include <mmsystem.h>
27
28#include "SDL_timer.h"
29#include "SDL_hints.h"
30
31
32/* The first (low-resolution) ticks value of the application */
33static DWORD start = 0;
34static BOOL ticks_started = FALSE; 
35
36/* Store if a high-resolution performance counter exists on the system */
37static BOOL hires_timer_available;
38/* The first high-resolution ticks value of the application */
39static LARGE_INTEGER hires_start_ticks;
40/* The number of ticks per second of the high-resolution performance counter */
41static LARGE_INTEGER hires_ticks_per_second;
42
43static void
44SDL_SetSystemTimerResolution(const UINT uPeriod)
45{
46#ifndef __WINRT__
47    static UINT timer_period = 0;
48
49    if (uPeriod != timer_period) {
50        if (timer_period) {
51            timeEndPeriod(timer_period);
52        }
53
54        timer_period = uPeriod;
55
56        if (timer_period) {
57            timeBeginPeriod(timer_period);
58        }
59    }
60#endif
61}
62
63static void SDLCALL
64SDL_TimerResolutionChanged(void *userdata, const char *name, const char *oldValue, const char *hint)
65{
66    UINT uPeriod;
67
68    /* Unless the hint says otherwise, let's have good sleep precision */
69    if (hint && *hint) {
70        uPeriod = SDL_atoi(hint);
71    } else {
72        uPeriod = 1;
73    }
74    if (uPeriod || oldValue != hint) {
75        SDL_SetSystemTimerResolution(uPeriod);
76    }
77}
78
79void
80SDL_TicksInit(void)
81{
82    if (ticks_started) {
83        return;
84    }
85    ticks_started = SDL_TRUE;
86
87    /* if we didn't set a precision, set it high. This affects lots of things
88       on Windows besides the SDL timers, like audio callbacks, etc. */
89    SDL_AddHintCallback(SDL_HINT_TIMER_RESOLUTION,
90                        SDL_TimerResolutionChanged, NULL);
91
92    /* Set first ticks value */
93    /* QueryPerformanceCounter has had problems in the past, but lots of games
94       use it, so we'll rely on it here.
95     */
96    if (QueryPerformanceFrequency(&hires_ticks_per_second) == TRUE) {
97        hires_timer_available = TRUE;
98        QueryPerformanceCounter(&hires_start_ticks);
99    } else {
100        hires_timer_available = FALSE;
101#ifndef __WINRT__
102        start = timeGetTime();
103#endif /* __WINRT__ */
104    }
105}
106
107void
108SDL_TicksQuit(void)
109{
110    SDL_DelHintCallback(SDL_HINT_TIMER_RESOLUTION,
111                        SDL_TimerResolutionChanged, NULL);
112
113    SDL_SetSystemTimerResolution(0);  /* always release our timer resolution request. */
114
115    start = 0;
116    ticks_started = SDL_FALSE;
117}
118
119Uint32
120SDL_GetTicks(void)
121{
122    DWORD now = 0;
123    LARGE_INTEGER hires_now;
124
125    if (!ticks_started) {
126        SDL_TicksInit();
127    }
128
129    if (hires_timer_available) {
130        QueryPerformanceCounter(&hires_now);
131
132        hires_now.QuadPart -= hires_start_ticks.QuadPart;
133        hires_now.QuadPart *= 1000;
134        hires_now.QuadPart /= hires_ticks_per_second.QuadPart;
135
136        return (DWORD) hires_now.QuadPart;
137    } else {
138#ifndef __WINRT__
139        now = timeGetTime();
140#endif /* __WINRT__ */
141    }
142
143    return (now - start);
144}
145
146Uint64
147SDL_GetPerformanceCounter(void)
148{
149    LARGE_INTEGER counter;
150
151    if (!QueryPerformanceCounter(&counter)) {
152        return SDL_GetTicks();
153    }
154    return counter.QuadPart;
155}
156
157Uint64
158SDL_GetPerformanceFrequency(void)
159{
160    LARGE_INTEGER frequency;
161
162    if (!QueryPerformanceFrequency(&frequency)) {
163        return 1000;
164    }
165    return frequency.QuadPart;
166}
167
168void
169SDL_Delay(Uint32 ms)
170{
171    /* Sleep() is not publicly available to apps in early versions of WinRT.
172     *
173     * Visual C++ 2013 Update 4 re-introduced Sleep() for Windows 8.1 and
174     * Windows Phone 8.1.
175     *
176     * Use the compiler version to determine availability.
177     *
178     * NOTE #1: _MSC_FULL_VER == 180030723 for Visual C++ 2013 Update 3.
179     * NOTE #2: Visual C++ 2013, when compiling for Windows 8.0 and
180     *    Windows Phone 8.0, uses the Visual C++ 2012 compiler to build
181     *    apps and libraries.
182     */
183#if defined(__WINRT__) && defined(_MSC_FULL_VER) && (_MSC_FULL_VER <= 180030723)
184    static HANDLE mutex = 0;
185    if (!mutex) {
186        mutex = CreateEventEx(0, 0, 0, EVENT_ALL_ACCESS);
187    }
188    WaitForSingleObjectEx(mutex, ms, FALSE);
189#else
190    if (!ticks_started) {
191        SDL_TicksInit();
192    }
193
194    Sleep(ms);
195#endif
196}
197
198#endif /* SDL_TIMER_WINDOWS */
199
200/* vi: set ts=4 sw=4 expandtab: */
201
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