src/thread/win32/SDL_syssem.c
author Sam Lantinga <slouken@libsdl.org>
Mon, 05 Jul 2010 12:32:44 -0700
changeset 4475 883a2f2ff43f
parent 3697 f7b03b6838cb
permissions -rw-r--r--
Fixed compile warning with latest mingw32 compiler
     1 /*
     2     SDL - Simple DirectMedia Layer
     3     Copyright (C) 1997-2010 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 #include "SDL_config.h"
    23 
    24 /* Semaphore functions using the Win32 API */
    25 
    26 #define WIN32_LEAN_AND_MEAN
    27 #include <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 volatile 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 /* vi: set ts=4 sw=4 expandtab: */