1 /* 2 Simple DirectMedia Layer 3 Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org> 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 22 #ifndef SDL_timer_h_ 23 #define SDL_timer_h_ 24 25 /** 26 * # CategoryTimer 27 * 28 * Header for the SDL time management routines. 29 */ 30 31 #include "SDL_stdinc.h" 32 #include "SDL_error.h" 33 34 #include "begin_code.h" 35 /* Set up for C function definitions, even when using C++ */ 36 #ifdef __cplusplus 37 extern "C" { 38 #endif 39 40 /** 41 * Get the number of milliseconds since SDL library initialization. 42 * 43 * This value wraps if the program runs for more than ~49 days. 44 * 45 * This function is not recommended as of SDL 2.0.18; use SDL_GetTicks64() 46 * instead, where the value doesn't wrap every ~49 days. There are places in 47 * SDL where we provide a 32-bit timestamp that can not change without 48 * breaking binary compatibility, though, so this function isn't officially 49 * deprecated. 50 * 51 * \returns an unsigned 32-bit value representing the number of milliseconds 52 * since the SDL library initialized. 53 * 54 * \since This function is available since SDL 2.0.0. 55 * 56 * \sa SDL_TICKS_PASSED 57 */ 58 extern DECLSPEC Uint32 SDLCALL SDL_GetTicks(void); 59 60 /** 61 * Get the number of milliseconds since SDL library initialization. 62 * 63 * Note that you should not use the SDL_TICKS_PASSED macro with values 64 * returned by this function, as that macro does clever math to compensate for 65 * the 32-bit overflow every ~49 days that SDL_GetTicks() suffers from. 64-bit 66 * values from this function can be safely compared directly. 67 * 68 * For example, if you want to wait 100 ms, you could do this: 69 * 70 * ```c 71 * const Uint64 timeout = SDL_GetTicks64() + 100; 72 * while (SDL_GetTicks64() < timeout) 73 { 74 * // ... do work until timeout has elapsed 75 * } 76 * ``` 77 * 78 * \returns an unsigned 64-bit value representing the number of milliseconds 79 * since the SDL library initialized. 80 * 81 * \since This function is available since SDL 2.0.18. 82 */ 83 extern DECLSPEC Uint64 SDLCALL SDL_GetTicks64(void); 84 85 /** 86 * Compare 32-bit SDL ticks values, and return true if `A` has passed `B`. 87 * 88 * This should be used with results from SDL_GetTicks(), as this macro 89 * attempts to deal with the 32-bit counter wrapping back to zero every ~49 90 * days, but should _not_ be used with SDL_GetTicks64(), which does not have 91 * that problem. 92 * 93 * For example, with SDL_GetTicks(), if you want to wait 100 ms, you could do 94 * this: 95 * 96 * ```c 97 * const Uint32 timeout = SDL_GetTicks() + 100; 98 * while (!SDL_TICKS_PASSED(SDL_GetTicks(), timeout)) 99 { 100 * // ... do work until timeout has elapsed 101 * } 102 * ``` 103 * 104 * Note that this does not handle tick differences greater than 2^31 so take 105 * care when using the above kind of code with large timeout delays (tens of 106 * days). 107 */ 108 #define SDL_TICKS_PASSED(A, B) ((Sint32)((B) - (A)) <= 0) 109 110 /** 111 * Get the current value of the high resolution counter. 112 * 113 * This function is typically used for profiling. 114 * 115 * The counter values are only meaningful relative to each other. Differences 116 * between values can be converted to times by using 117 * SDL_GetPerformanceFrequency(). 118 * 119 * \returns the current counter value. 120 * 121 * \since This function is available since SDL 2.0.0. 122 * 123 * \sa SDL_GetPerformanceFrequency 124 */ 125 extern DECLSPEC Uint64 SDLCALL SDL_GetPerformanceCounter(void); 126 127 /** 128 * Get the count per second of the high resolution counter. 129 * 130 * \returns a platform-specific count per second. 131 * 132 * \since This function is available since SDL 2.0.0. 133 * 134 * \sa SDL_GetPerformanceCounter 135 */ 136 extern DECLSPEC Uint64 SDLCALL SDL_GetPerformanceFrequency(void); 137 138 /** 139 * Wait a specified number of milliseconds before returning. 140 * 141 * This function waits a specified number of milliseconds before returning. It 142 * waits at least the specified time, but possibly longer due to OS 143 * scheduling. 144 * 145 * \param ms the number of milliseconds to delay. 146 * 147 * \since This function is available since SDL 2.0.0. 148 */ 149 extern DECLSPEC void SDLCALL SDL_Delay(Uint32 ms); 150 151 /** 152 * Function prototype for the timer callback function. 153 * 154 * The callback function is passed the current timer interval and returns the 155 * next timer interval. If the returned value is the same as the one passed 156 * in, the periodic alarm continues, otherwise a new alarm is scheduled. If 157 * the callback returns 0, the periodic alarm is cancelled. 158 */ 159 typedef Uint32 (SDLCALL * SDL_TimerCallback) (Uint32 interval, void *param); 160 161 /** 162 * Definition of the timer ID type. 163 */ 164 typedef int SDL_TimerID; 165 166 /** 167 * Call a callback function at a future time. 168 * 169 * If you use this function, you must pass `SDL_INIT_TIMER` to SDL_Init(). 170 * 171 * The callback function is passed the current timer interval and the user 172 * supplied parameter from the SDL_AddTimer() call and should return the next 173 * timer interval. If the value returned from the callback is 0, the timer is 174 * canceled. 175 * 176 * The callback is run on a separate thread. 177 * 178 * Timers take into account the amount of time it took to execute the 179 * callback. For example, if the callback took 250 ms to execute and returned 180 * 1000 (ms), the timer would only wait another 750 ms before its next 181 * iteration. 182 * 183 * Timing may be inexact due to OS scheduling. Be sure to note the current 184 * time with SDL_GetTicks() or SDL_GetPerformanceCounter() in case your 185 * callback needs to adjust for variances. 186 * 187 * \param interval the timer delay, in milliseconds, passed to `callback`. 188 * \param callback the SDL_TimerCallback function to call when the specified 189 * `interval` elapses. 190 * \param param a pointer that is passed to `callback`. 191 * \returns a timer ID or 0 if an error occurs; call SDL_GetError() for more 192 * information. 193 * 194 * \since This function is available since SDL 2.0.0. 195 * 196 * \sa SDL_RemoveTimer 197 */ 198 extern DECLSPEC SDL_TimerID SDLCALL SDL_AddTimer(Uint32 interval, 199 SDL_TimerCallback callback, 200 void *param); 201 202 /** 203 * Remove a timer created with SDL_AddTimer(). 204 * 205 * \param id the ID of the timer to remove. 206 * \returns SDL_TRUE if the timer is removed or SDL_FALSE if the timer wasn't 207 * found. 208 * 209 * \since This function is available since SDL 2.0.0. 210 * 211 * \sa SDL_AddTimer 212 */ 213 extern DECLSPEC SDL_bool SDLCALL SDL_RemoveTimer(SDL_TimerID id); 214 215 216 /* Ends C function definitions when using C++ */ 217 #ifdef __cplusplus 218 } 219 #endif 220 #include "close_code.h" 221 222 #endif /* SDL_timer_h_ */ 223 224 /* vi: set ts=4 sw=4 expandtab: */