src/thread/windows/SDL_syssem.c
author Ryan C. Gordon <icculus@icculus.org>
Sun, 31 Mar 2013 12:48:50 -0400
changeset 7037 3fedf1f25b94
parent 6885 700f1b25f77f
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.
slouken@0
     1
/*
slouken@5535
     2
  Simple DirectMedia Layer
slouken@6885
     3
  Copyright (C) 1997-2013 Sam Lantinga <slouken@libsdl.org>
slouken@0
     4
slouken@5535
     5
  This software is provided 'as-is', without any express or implied
slouken@5535
     6
  warranty.  In no event will the authors be held liable for any damages
slouken@5535
     7
  arising from the use of this software.
slouken@0
     8
slouken@5535
     9
  Permission is granted to anyone to use this software for any purpose,
slouken@5535
    10
  including commercial applications, and to alter it and redistribute it
slouken@5535
    11
  freely, subject to the following restrictions:
slouken@0
    12
slouken@5535
    13
  1. The origin of this software must not be misrepresented; you must not
slouken@5535
    14
     claim that you wrote the original software. If you use this software
slouken@5535
    15
     in a product, an acknowledgment in the product documentation would be
slouken@5535
    16
     appreciated but is not required.
slouken@5535
    17
  2. Altered source versions must be plainly marked as such, and must not be
slouken@5535
    18
     misrepresented as being the original software.
slouken@5535
    19
  3. This notice may not be removed or altered from any source distribution.
slouken@0
    20
*/
slouken@1402
    21
#include "SDL_config.h"
slouken@0
    22
slouken@6044
    23
#if SDL_THREAD_WINDOWS
slouken@6044
    24
slouken@0
    25
/* Semaphore functions using the Win32 API */
slouken@0
    26
slouken@5090
    27
#include "../../core/windows/SDL_windows.h"
slouken@0
    28
slouken@0
    29
#include "SDL_thread.h"
slouken@0
    30
slouken@1895
    31
struct SDL_semaphore
slouken@1895
    32
{
slouken@1895
    33
    HANDLE id;
slouken@5086
    34
    LONG count;
slouken@0
    35
};
slouken@0
    36
slouken@0
    37
slouken@0
    38
/* Create a semaphore */
slouken@1895
    39
SDL_sem *
slouken@1895
    40
SDL_CreateSemaphore(Uint32 initial_value)
slouken@0
    41
{
slouken@1895
    42
    SDL_sem *sem;
slouken@0
    43
slouken@1895
    44
    /* Allocate sem memory */
slouken@1895
    45
    sem = (SDL_sem *) SDL_malloc(sizeof(*sem));
slouken@1895
    46
    if (sem) {
slouken@1895
    47
        /* Create the semaphore, with max value 32K */
slouken@1895
    48
        sem->id = CreateSemaphore(NULL, initial_value, 32 * 1024, NULL);
slouken@1895
    49
        sem->count = initial_value;
slouken@1895
    50
        if (!sem->id) {
slouken@1895
    51
            SDL_SetError("Couldn't create semaphore");
slouken@1895
    52
            SDL_free(sem);
slouken@1895
    53
            sem = NULL;
slouken@1895
    54
        }
slouken@1895
    55
    } else {
slouken@1895
    56
        SDL_OutOfMemory();
slouken@1895
    57
    }
slouken@1895
    58
    return (sem);
slouken@0
    59
}
slouken@0
    60
slouken@0
    61
/* Free the semaphore */
slouken@1895
    62
void
slouken@1895
    63
SDL_DestroySemaphore(SDL_sem * sem)
slouken@0
    64
{
slouken@1895
    65
    if (sem) {
slouken@1895
    66
        if (sem->id) {
slouken@1895
    67
            CloseHandle(sem->id);
slouken@1895
    68
            sem->id = 0;
slouken@1895
    69
        }
slouken@1895
    70
        SDL_free(sem);
slouken@1895
    71
    }
slouken@0
    72
}
slouken@0
    73
slouken@1895
    74
int
slouken@1895
    75
SDL_SemWaitTimeout(SDL_sem * sem, Uint32 timeout)
slouken@0
    76
{
slouken@1895
    77
    int retval;
slouken@1895
    78
    DWORD dwMilliseconds;
slouken@0
    79
slouken@1895
    80
    if (!sem) {
icculus@7037
    81
        return SDL_SetError("Passed a NULL sem");
slouken@1895
    82
    }
slouken@0
    83
slouken@1895
    84
    if (timeout == SDL_MUTEX_MAXWAIT) {
slouken@1895
    85
        dwMilliseconds = INFINITE;
slouken@1895
    86
    } else {
slouken@1895
    87
        dwMilliseconds = (DWORD) timeout;
slouken@1895
    88
    }
slouken@1895
    89
    switch (WaitForSingleObject(sem->id, dwMilliseconds)) {
slouken@1895
    90
    case WAIT_OBJECT_0:
slouken@3069
    91
        InterlockedDecrement(&sem->count);
slouken@1895
    92
        retval = 0;
slouken@1895
    93
        break;
slouken@1895
    94
    case WAIT_TIMEOUT:
slouken@1895
    95
        retval = SDL_MUTEX_TIMEDOUT;
slouken@1895
    96
        break;
slouken@1895
    97
    default:
icculus@7037
    98
        retval = SDL_SetError("WaitForSingleObject() failed");
slouken@1895
    99
        break;
slouken@1895
   100
    }
slouken@1895
   101
    return retval;
slouken@0
   102
}
slouken@0
   103
slouken@1895
   104
int
slouken@1895
   105
SDL_SemTryWait(SDL_sem * sem)
slouken@0
   106
{
slouken@1895
   107
    return SDL_SemWaitTimeout(sem, 0);
slouken@0
   108
}
slouken@0
   109
slouken@1895
   110
int
slouken@1895
   111
SDL_SemWait(SDL_sem * sem)
slouken@0
   112
{
slouken@1895
   113
    return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT);
slouken@0
   114
}
slouken@0
   115
slouken@0
   116
/* Returns the current count of the semaphore */
slouken@1895
   117
Uint32
slouken@1895
   118
SDL_SemValue(SDL_sem * sem)
slouken@0
   119
{
slouken@1895
   120
    if (!sem) {
slouken@1895
   121
        SDL_SetError("Passed a NULL sem");
slouken@1895
   122
        return 0;
slouken@1895
   123
    }
slouken@4475
   124
    return (Uint32)sem->count;
slouken@0
   125
}
slouken@0
   126
slouken@1895
   127
int
slouken@1895
   128
SDL_SemPost(SDL_sem * sem)
slouken@0
   129
{
slouken@1895
   130
    if (!sem) {
icculus@7037
   131
        return SDL_SetError("Passed a NULL sem");
slouken@1895
   132
    }
slouken@1895
   133
    /* Increase the counter in the first place, because
slouken@1895
   134
     * after a successful release the semaphore may
slouken@1895
   135
     * immediately get destroyed by another thread which
slouken@1895
   136
     * is waiting for this semaphore.
slouken@1895
   137
     */
slouken@3069
   138
    InterlockedIncrement(&sem->count);
slouken@1895
   139
    if (ReleaseSemaphore(sem->id, 1, NULL) == FALSE) {
slouken@3071
   140
        InterlockedDecrement(&sem->count);      /* restore */
icculus@7037
   141
        return SDL_SetError("ReleaseSemaphore() failed");
slouken@1895
   142
    }
slouken@1895
   143
    return 0;
slouken@0
   144
}
slouken@1895
   145
slouken@6044
   146
#endif /* SDL_THREAD_WINDOWS */
slouken@6044
   147
slouken@1895
   148
/* vi: set ts=4 sw=4 expandtab: */