include/SDL_timer.h
author Sam Lantinga <slouken@libsdl.org>
Sat, 26 Sep 2009 23:17:08 +0000
branchSDL-1.2
changeset 4246 8b8314cc34a6
parent 4217 4c4113c2162c
child 6137 4720145f848b
permissions -rw-r--r--
Fixed bug #810

Lauri Kenttä 2009-09-26 06:42:23 PDT

Support for disabling stdio redirect with environment variables.
     1 /*
     2     SDL - Simple DirectMedia Layer
     3     Copyright (C) 1997-2009 Sam Lantinga
     4 
     5     This library is free software; you can redistribute it and/or
     6     modify it under the terms of the GNU Lesser General Public
     7     License as published by the Free Software Foundation; either
     8     version 2.1 of the License, or (at your option) any later version.
     9 
    10     This library is distributed in the hope that it will be useful,
    11     but WITHOUT ANY WARRANTY; without even the implied warranty of
    12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    13     Lesser General Public License for more details.
    14 
    15     You should have received a copy of the GNU Lesser General Public
    16     License along with this library; if not, write to the Free Software
    17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
    18 
    19     Sam Lantinga
    20     slouken@libsdl.org
    21 */
    22 
    23 #ifndef _SDL_timer_h
    24 #define _SDL_timer_h
    25 
    26 /** @file SDL_timer.h
    27  *  Header for the SDL time management routines
    28  */
    29 
    30 #include "SDL_stdinc.h"
    31 #include "SDL_error.h"
    32 
    33 #include "begin_code.h"
    34 /* Set up for C function definitions, even when using C++ */
    35 #ifdef __cplusplus
    36 extern "C" {
    37 #endif
    38 
    39 /** This is the OS scheduler timeslice, in milliseconds */
    40 #define SDL_TIMESLICE		10
    41 
    42 /** This is the maximum resolution of the SDL timer on all platforms */
    43 #define TIMER_RESOLUTION	10	/**< Experimentally determined */
    44 
    45 /**
    46  * Get the number of milliseconds since the SDL library initialization.
    47  * Note that this value wraps if the program runs for more than ~49 days.
    48  */ 
    49 extern DECLSPEC Uint32 SDLCALL SDL_GetTicks(void);
    50 
    51 /** Wait a specified number of milliseconds before returning */
    52 extern DECLSPEC void SDLCALL SDL_Delay(Uint32 ms);
    53 
    54 /** Function prototype for the timer callback function */
    55 typedef Uint32 (SDLCALL *SDL_TimerCallback)(Uint32 interval);
    56 
    57 /**
    58  * Set a callback to run after the specified number of milliseconds has
    59  * elapsed. The callback function is passed the current timer interval
    60  * and returns the next timer interval.  If the returned value is the 
    61  * same as the one passed in, the periodic alarm continues, otherwise a
    62  * new alarm is scheduled.  If the callback returns 0, the periodic alarm
    63  * is cancelled.
    64  *
    65  * To cancel a currently running timer, call SDL_SetTimer(0, NULL);
    66  *
    67  * The timer callback function may run in a different thread than your
    68  * main code, and so shouldn't call any functions from within itself.
    69  *
    70  * The maximum resolution of this timer is 10 ms, which means that if
    71  * you request a 16 ms timer, your callback will run approximately 20 ms
    72  * later on an unloaded system.  If you wanted to set a flag signaling
    73  * a frame update at 30 frames per second (every 33 ms), you might set a 
    74  * timer for 30 ms:
    75  *   @code SDL_SetTimer((33/10)*10, flag_update); @endcode
    76  *
    77  * If you use this function, you need to pass SDL_INIT_TIMER to SDL_Init().
    78  *
    79  * Under UNIX, you should not use raise or use SIGALRM and this function
    80  * in the same program, as it is implemented using setitimer().  You also
    81  * should not use this function in multi-threaded applications as signals
    82  * to multi-threaded apps have undefined behavior in some implementations.
    83  *
    84  * This function returns 0 if successful, or -1 if there was an error.
    85  */
    86 extern DECLSPEC int SDLCALL SDL_SetTimer(Uint32 interval, SDL_TimerCallback callback);
    87 
    88 /** @name New timer API
    89  * New timer API, supports multiple timers
    90  * Written by Stephane Peter <megastep@lokigames.com>
    91  */
    92 /*@{*/
    93 
    94 /**
    95  * Function prototype for the new timer callback function.
    96  * The callback function is passed the current timer interval and returns
    97  * the next timer interval.  If the returned value is the same as the one
    98  * passed in, the periodic alarm continues, otherwise a new alarm is
    99  * scheduled.  If the callback returns 0, the periodic alarm is cancelled.
   100  */
   101 typedef Uint32 (SDLCALL *SDL_NewTimerCallback)(Uint32 interval, void *param);
   102 
   103 /** Definition of the timer ID type */
   104 typedef struct _SDL_TimerID *SDL_TimerID;
   105 
   106 /** Add a new timer to the pool of timers already running.
   107  *  Returns a timer ID, or NULL when an error occurs.
   108  */
   109 extern DECLSPEC SDL_TimerID SDLCALL SDL_AddTimer(Uint32 interval, SDL_NewTimerCallback callback, void *param);
   110 
   111 /**
   112  * Remove one of the multiple timers knowing its ID.
   113  * Returns a boolean value indicating success.
   114  */
   115 extern DECLSPEC SDL_bool SDLCALL SDL_RemoveTimer(SDL_TimerID t);
   116 
   117 /*@}*/
   118 
   119 /* Ends C function definitions when using C++ */
   120 #ifdef __cplusplus
   121 }
   122 #endif
   123 #include "close_code.h"
   124 
   125 #endif /* _SDL_timer_h */