include/SDL_thread.h
author Sam Lantinga <slouken@libsdl.org>
Fri, 25 Mar 2011 12:44:06 -0700
changeset 5509 5b1b4d820d10
parent 5506 82a09d5d0f07
child 5535 96594ac5fd1a
permissions -rw-r--r--
The API sets the priority for the current thread, not an arbitrary thread.

Implemented thread priority as the 'nice' value on Linux. High priority threads require root permissions (you shouldn't give your game root permissions though!)
     1 /*
     2     SDL - Simple DirectMedia Layer
     3     Copyright (C) 1997-2011 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_thread_h
    24 #define _SDL_thread_h
    25 
    26 /**
    27  *  \file SDL_thread.h
    28  *  
    29  *  Header for the SDL thread management routines.
    30  */
    31 
    32 #include "SDL_stdinc.h"
    33 #include "SDL_error.h"
    34 
    35 /* Thread synchronization primitives */
    36 #include "SDL_mutex.h"
    37 
    38 #include "begin_code.h"
    39 /* Set up for C function definitions, even when using C++ */
    40 #ifdef __cplusplus
    41 /* *INDENT-OFF* */
    42 extern "C" {
    43 /* *INDENT-ON* */
    44 #endif
    45 
    46 /* The SDL thread structure, defined in SDL_thread.c */
    47 struct SDL_Thread;
    48 typedef struct SDL_Thread SDL_Thread;
    49 
    50 /* The SDL thread ID */
    51 typedef unsigned long SDL_threadID;
    52 
    53 /* The SDL thread priority
    54  *
    55  * Note: On many systems you require special privileges to set high priority.
    56  */
    57 typedef enum {
    58     SDL_THREAD_PRIORITY_LOW,
    59     SDL_THREAD_PRIORITY_NORMAL,
    60     SDL_THREAD_PRIORITY_HIGH
    61 } SDL_ThreadPriority;
    62 
    63 /* The function passed to SDL_CreateThread()
    64    It is passed a void* user context parameter and returns an int.
    65  */
    66 typedef int (SDLCALL * SDL_ThreadFunction) (void *data);
    67 
    68 #if defined(__WIN32__) && !defined(HAVE_LIBC)
    69 /**
    70  *  \file SDL_thread.h
    71  *  
    72  *  We compile SDL into a DLL. This means, that it's the DLL which
    73  *  creates a new thread for the calling process with the SDL_CreateThread()
    74  *  API. There is a problem with this, that only the RTL of the SDL.DLL will
    75  *  be initialized for those threads, and not the RTL of the calling 
    76  *  application!
    77  *  
    78  *  To solve this, we make a little hack here.
    79  *  
    80  *  We'll always use the caller's _beginthread() and _endthread() APIs to
    81  *  start a new thread. This way, if it's the SDL.DLL which uses this API,
    82  *  then the RTL of SDL.DLL will be used to create the new thread, and if it's
    83  *  the application, then the RTL of the application will be used.
    84  *  
    85  *  So, in short:
    86  *  Always use the _beginthread() and _endthread() of the calling runtime 
    87  *  library!
    88  */
    89 #define SDL_PASSED_BEGINTHREAD_ENDTHREAD
    90 #ifndef _WIN32_WCE
    91 #include <process.h>            /* This has _beginthread() and _endthread() defined! */
    92 #endif
    93 
    94 #ifdef __GNUC__
    95 typedef unsigned long (__cdecl * pfnSDL_CurrentBeginThread) (void *, unsigned,
    96                                                              unsigned
    97                                                              (__stdcall *
    98                                                               func) (void *),
    99                                                              void *arg,
   100                                                              unsigned,
   101                                                              unsigned
   102                                                              *threadID);
   103 typedef void (__cdecl * pfnSDL_CurrentEndThread) (unsigned code);
   104 #else
   105 typedef uintptr_t(__cdecl * pfnSDL_CurrentBeginThread) (void *, unsigned,
   106                                                         unsigned (__stdcall *
   107                                                                   func) (void
   108                                                                          *),
   109                                                         void *arg, unsigned,
   110                                                         unsigned *threadID);
   111 typedef void (__cdecl * pfnSDL_CurrentEndThread) (unsigned code);
   112 #endif
   113 
   114 /**
   115  *  Create a thread.
   116  */
   117 extern DECLSPEC SDL_Thread *SDLCALL
   118 SDL_CreateThread(SDL_ThreadFunction fn, void *data,
   119                  pfnSDL_CurrentBeginThread pfnBeginThread,
   120                  pfnSDL_CurrentEndThread pfnEndThread);
   121 
   122 #if defined(_WIN32_WCE)
   123 
   124 /**
   125  *  Create a thread.
   126  */
   127 #define SDL_CreateThread(fn, data) SDL_CreateThread(fn, data, NULL, NULL)
   128 
   129 #else
   130 
   131 /**
   132  *  Create a thread.
   133  */
   134 #define SDL_CreateThread(fn, data) SDL_CreateThread(fn, data, _beginthreadex, _endthreadex)
   135 
   136 #endif
   137 #else
   138 
   139 /**
   140  *  Create a thread.
   141  */
   142 extern DECLSPEC SDL_Thread *SDLCALL
   143 SDL_CreateThread(SDL_ThreadFunction fn, void *data);
   144 
   145 #endif
   146 
   147 /**
   148  *  Get the thread identifier for the current thread.
   149  */
   150 extern DECLSPEC SDL_threadID SDLCALL SDL_ThreadID(void);
   151 
   152 /**
   153  *  Get the thread identifier for the specified thread.
   154  *  
   155  *  Equivalent to SDL_ThreadID() if the specified thread is NULL.
   156  */
   157 extern DECLSPEC SDL_threadID SDLCALL SDL_GetThreadID(SDL_Thread * thread);
   158 
   159 /**
   160  *  Set the priority for the current thread
   161  */
   162 extern DECLSPEC int SDLCALL SDL_SetThreadPriority(SDL_ThreadPriority priority);
   163 
   164 /**
   165  *  Wait for a thread to finish.
   166  *  
   167  *  The return code for the thread function is placed in the area
   168  *  pointed to by \c status, if \c status is not NULL.
   169  */
   170 extern DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread * thread, int *status);
   171 
   172 
   173 /* Ends C function definitions when using C++ */
   174 #ifdef __cplusplus
   175 /* *INDENT-OFF* */
   176 }
   177 /* *INDENT-ON* */
   178 #endif
   179 #include "close_code.h"
   180 
   181 #endif /* _SDL_thread_h */
   182 
   183 /* vi: set ts=4 sw=4 expandtab: */