src/thread/windows/SDL_syssem.c
author Sam Lantinga
Sat, 31 Dec 2011 09:28:07 -0500
changeset 6138 4c64952a58fb
parent 6044 35448a5ea044
child 6430 48d519500f7e
permissions -rwxr-xr-x
Happy New Year!
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2012 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 #include "SDL_config.h"
    22 
    23 #if SDL_THREAD_WINDOWS
    24 
    25 /* Semaphore functions using the Win32 API */
    26 
    27 #include "../../core/windows/SDL_windows.h"
    28 
    29 #include "SDL_thread.h"
    30 #if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
    31 #include "win_ce_semaphore.h"
    32 #endif
    33 
    34 
    35 struct SDL_semaphore
    36 {
    37 #if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
    38     SYNCHHANDLE id;
    39 #else
    40     HANDLE id;
    41 #endif
    42     LONG count;
    43 };
    44 
    45 
    46 /* Create a semaphore */
    47 SDL_sem *
    48 SDL_CreateSemaphore(Uint32 initial_value)
    49 {
    50     SDL_sem *sem;
    51 
    52     /* Allocate sem memory */
    53     sem = (SDL_sem *) SDL_malloc(sizeof(*sem));
    54     if (sem) {
    55         /* Create the semaphore, with max value 32K */
    56 #if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
    57         sem->id = CreateSemaphoreCE(NULL, initial_value, 32 * 1024, NULL);
    58 #else
    59         sem->id = CreateSemaphore(NULL, initial_value, 32 * 1024, NULL);
    60 #endif
    61         sem->count = initial_value;
    62         if (!sem->id) {
    63             SDL_SetError("Couldn't create semaphore");
    64             SDL_free(sem);
    65             sem = NULL;
    66         }
    67     } else {
    68         SDL_OutOfMemory();
    69     }
    70     return (sem);
    71 }
    72 
    73 /* Free the semaphore */
    74 void
    75 SDL_DestroySemaphore(SDL_sem * sem)
    76 {
    77     if (sem) {
    78         if (sem->id) {
    79 #if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
    80             CloseSynchHandle(sem->id);
    81 #else
    82             CloseHandle(sem->id);
    83 #endif
    84             sem->id = 0;
    85         }
    86         SDL_free(sem);
    87     }
    88 }
    89 
    90 int
    91 SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout)
    92 {
    93     int retval;
    94     DWORD dwMilliseconds;
    95 
    96     if (!sem) {
    97         SDL_SetError("Passed a NULL sem");
    98         return -1;
    99     }
   100 
   101     if (timeout == SDL_MUTEX_MAXWAIT) {
   102         dwMilliseconds = INFINITE;
   103     } else {
   104         dwMilliseconds = (DWORD) timeout;
   105     }
   106 #if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
   107     switch (WaitForSemaphoreCE(sem->id, dwMilliseconds)) {
   108 #else
   109     switch (WaitForSingleObject(sem->id, dwMilliseconds)) {
   110 #endif
   111     case WAIT_OBJECT_0:
   112         InterlockedDecrement(&sem->count);
   113         retval = 0;
   114         break;
   115     case WAIT_TIMEOUT:
   116         retval = SDL_MUTEX_TIMEDOUT;
   117         break;
   118     default:
   119         SDL_SetError("WaitForSingleObject() failed");
   120         retval = -1;
   121         break;
   122     }
   123     return retval;
   124 }
   125 
   126 int
   127 SDL_SemTryWait(SDL_sem * sem)
   128 {
   129     return SDL_SemWaitTimeout(sem, 0);
   130 }
   131 
   132 int
   133 SDL_SemWait(SDL_sem * sem)
   134 {
   135     return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
   136 }
   137 
   138 /* Returns the current count of the semaphore */
   139 Uint32
   140 SDL_SemValue(SDL_sem * sem)
   141 {
   142     if (!sem) {
   143         SDL_SetError("Passed a NULL sem");
   144         return 0;
   145     }
   146     return (Uint32)sem->count;
   147 }
   148 
   149 int
   150 SDL_SemPost(SDL_sem * sem)
   151 {
   152     if (!sem) {
   153         SDL_SetError("Passed a NULL sem");
   154         return -1;
   155     }
   156     /* Increase the counter in the first place, because
   157      * after a successful release the semaphore may
   158      * immediately get destroyed by another thread which
   159      * is waiting for this semaphore.
   160      */
   161     InterlockedIncrement(&sem->count);
   162 #if defined(_WIN32_WCE) && (_WIN32_WCE < 300)
   163     if (ReleaseSemaphoreCE(sem->id, 1, NULL) == FALSE) {
   164 #else
   165     if (ReleaseSemaphore(sem->id, 1, NULL) == FALSE) {
   166 #endif
   167         InterlockedDecrement(&sem->count);      /* restore */
   168         SDL_SetError("ReleaseSemaphore() failed");
   169         return -1;
   170     }
   171     return 0;
   172 }
   173 
   174 #endif /* SDL_THREAD_WINDOWS */
   175 
   176 /* vi: set ts=4 sw=4 expandtab: */