src/thread/psp/SDL_sysmutex.c
author Ryan C. Gordon <icculus@icculus.org>
Sun, 31 Mar 2013 12:48:50 -0400
changeset 7037 3fedf1f25b94
parent 7009 161b7b6a5303
child 8093 b43765095a6f
permissions -rw-r--r--
Make SDL_SetError and friends unconditionally return -1.

This lets us change things like this...

if (Failed) {
SDL_SetError("We failed");
return -1;
}

...into this...

if (Failed) {
return SDL_SetError("We failed");
}


Fixes Bugzilla #1778.
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2013 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 /* An implementation of mutexes using semaphores */
    24 
    25 #include "SDL_thread.h"
    26 #include "SDL_systhread_c.h"
    27 
    28 
    29 struct SDL_mutex
    30 {
    31     int recursive;
    32     SDL_threadID owner;
    33     SDL_sem *sem;
    34 };
    35 
    36 /* Create a mutex */
    37 SDL_mutex *
    38 SDL_CreateMutex(void)
    39 {
    40     SDL_mutex *mutex;
    41 
    42     /* Allocate mutex memory */
    43     mutex = (SDL_mutex *) SDL_malloc(sizeof(*mutex));
    44     if (mutex) {
    45         /* Create the mutex semaphore, with initial value 1 */
    46         mutex->sem = SDL_CreateSemaphore(1);
    47         mutex->recursive = 0;
    48         mutex->owner = 0;
    49         if (!mutex->sem) {
    50             SDL_free(mutex);
    51             mutex = NULL;
    52         }
    53     } else {
    54         SDL_OutOfMemory();
    55     }
    56     return mutex;
    57 }
    58 
    59 /* Free the mutex */
    60 void
    61 SDL_DestroyMutex(SDL_mutex * mutex)
    62 {
    63     if (mutex) {
    64         if (mutex->sem) {
    65             SDL_DestroySemaphore(mutex->sem);
    66         }
    67         SDL_free(mutex);
    68     }
    69 }
    70 
    71 /* Lock the semaphore */
    72 int
    73 SDL_mutexP(SDL_mutex * mutex)
    74 {
    75 #if SDL_THREADS_DISABLED
    76     return 0;
    77 #else
    78     SDL_threadID this_thread;
    79 
    80     if (mutex == NULL) {
    81         return SDL_SetError("Passed a NULL mutex");
    82     }
    83 
    84     this_thread = SDL_ThreadID();
    85     if (mutex->owner == this_thread) {
    86         ++mutex->recursive;
    87     } else {
    88         /* The order of operations is important.
    89            We set the locking thread id after we obtain the lock
    90            so unlocks from other threads will fail.
    91          */
    92         SDL_SemWait(mutex->sem);
    93         mutex->owner = this_thread;
    94         mutex->recursive = 0;
    95     }
    96 
    97     return 0;
    98 #endif /* SDL_THREADS_DISABLED */
    99 }
   100 
   101 /* Unlock the mutex */
   102 int
   103 SDL_mutexV(SDL_mutex * mutex)
   104 {
   105 #if SDL_THREADS_DISABLED
   106     return 0;
   107 #else
   108     if (mutex == NULL) {
   109         return SDL_SetError("Passed a NULL mutex");
   110     }
   111 
   112     /* If we don't own the mutex, we can't unlock it */
   113     if (SDL_ThreadID() != mutex->owner) {
   114         return SDL_SetError("mutex not owned by this thread");
   115     }
   116 
   117     if (mutex->recursive) {
   118         --mutex->recursive;
   119     } else {
   120         /* The order of operations is important.
   121            First reset the owner so another thread doesn't lock
   122            the mutex and set the ownership before we reset it,
   123            then release the lock semaphore.
   124          */
   125         mutex->owner = 0;
   126         SDL_SemPost(mutex->sem);
   127     }
   128     return 0;
   129 #endif /* SDL_THREADS_DISABLED */
   130 }
   131 
   132 /* vi: set ts=4 sw=4 expandtab: */