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1 /* |
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2 SDL - Simple DirectMedia Layer |
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3 Copyright (C) 1997-2006 Sam Lantinga |
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4 |
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5 This library is free software; you can redistribute it and/or |
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6 modify it under the terms of the GNU Lesser General Public |
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7 License as published by the Free Software Foundation; either |
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8 version 2.1 of the License, or (at your option) any later version. |
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9 |
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10 This library is distributed in the hope that it will be useful, |
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 Lesser General Public License for more details. |
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14 |
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15 You should have received a copy of the GNU Lesser General Public |
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16 License along with this library; if not, write to the Free Software |
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17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
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18 |
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19 Sam Lantinga |
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20 slouken@libsdl.org |
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21 */ |
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22 |
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23 #ifndef _SDL_timer_h |
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24 #define _SDL_timer_h |
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25 |
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26 /* Header for the SDL time management routines */ |
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27 |
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28 #include "SDL_stdinc.h" |
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29 #include "SDL_error.h" |
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30 |
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31 #include "begin_code.h" |
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32 /* Set up for C function definitions, even when using C++ */ |
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33 #ifdef __cplusplus |
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34 extern "C" { |
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35 #endif |
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36 |
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37 /* This is the OS scheduler timeslice, in milliseconds */ |
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38 #define SDL_TIMESLICE 10 |
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39 |
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40 /* This is the maximum resolution of the SDL timer on all platforms */ |
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41 #define TIMER_RESOLUTION 10 /* Experimentally determined */ |
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42 |
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43 /* Get the number of milliseconds since the SDL library initialization. |
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44 * Note that this value wraps if the program runs for more than ~49 days. |
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45 */ |
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46 extern DECLSPEC Uint32 SDLCALL SDL_GetTicks(void); |
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47 |
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48 /* Wait a specified number of milliseconds before returning */ |
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49 extern DECLSPEC void SDLCALL SDL_Delay(Uint32 ms); |
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50 |
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51 /* Function prototype for the timer callback function */ |
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52 typedef Uint32 (SDLCALL *SDL_TimerCallback)(Uint32 interval); |
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53 |
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54 /* Set a callback to run after the specified number of milliseconds has |
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55 * elapsed. The callback function is passed the current timer interval |
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56 * and returns the next timer interval. If the returned value is the |
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57 * same as the one passed in, the periodic alarm continues, otherwise a |
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58 * new alarm is scheduled. If the callback returns 0, the periodic alarm |
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59 * is cancelled. |
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60 * |
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61 * To cancel a currently running timer, call SDL_SetTimer(0, NULL); |
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62 * |
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63 * The timer callback function may run in a different thread than your |
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64 * main code, and so shouldn't call any functions from within itself. |
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65 * |
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66 * The maximum resolution of this timer is 10 ms, which means that if |
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67 * you request a 16 ms timer, your callback will run approximately 20 ms |
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68 * later on an unloaded system. If you wanted to set a flag signaling |
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69 * a frame update at 30 frames per second (every 33 ms), you might set a |
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70 * timer for 30 ms: |
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71 * SDL_SetTimer((33/10)*10, flag_update); |
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72 * |
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73 * If you use this function, you need to pass SDL_INIT_TIMER to SDL_Init(). |
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74 * |
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75 * Under UNIX, you should not use raise or use SIGALRM and this function |
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76 * in the same program, as it is implemented using setitimer(). You also |
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77 * should not use this function in multi-threaded applications as signals |
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78 * to multi-threaded apps have undefined behavior in some implementations. |
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79 * |
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80 * This function returns 0 if successful, or -1 if there was an error. |
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81 */ |
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82 extern DECLSPEC int SDLCALL SDL_SetTimer(Uint32 interval, SDL_TimerCallback callback); |
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83 |
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84 /* New timer API, supports multiple timers |
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85 * Written by Stephane Peter <megastep@lokigames.com> |
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86 */ |
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87 |
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88 /* Function prototype for the new timer callback function. |
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89 * The callback function is passed the current timer interval and returns |
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90 * the next timer interval. If the returned value is the same as the one |
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91 * passed in, the periodic alarm continues, otherwise a new alarm is |
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92 * scheduled. If the callback returns 0, the periodic alarm is cancelled. |
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93 */ |
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94 typedef Uint32 (SDLCALL *SDL_NewTimerCallback)(Uint32 interval, void *param); |
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95 |
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96 /* Definition of the timer ID type */ |
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97 typedef struct _SDL_TimerID *SDL_TimerID; |
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98 |
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99 /* Add a new timer to the pool of timers already running. |
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100 Returns a timer ID, or NULL when an error occurs. |
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101 */ |
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102 extern DECLSPEC SDL_TimerID SDLCALL SDL_AddTimer(Uint32 interval, SDL_NewTimerCallback callback, void *param); |
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103 |
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104 /* Remove one of the multiple timers knowing its ID. |
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105 * Returns a boolean value indicating success. |
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106 */ |
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107 extern DECLSPEC SDL_bool SDLCALL SDL_RemoveTimer(SDL_TimerID t); |
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108 |
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109 /* Ends C function definitions when using C++ */ |
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110 #ifdef __cplusplus |
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111 } |
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112 #endif |
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113 #include "close_code.h" |
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114 |
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115 #endif /* _SDL_timer_h */ |