workbench/libs/thread/createmutex.c

   1 /*
   2  * thread.library - threading and synchronisation primitives
   3  *
   4  * Copyright © 2007 Robert Norris
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the same terms as AROS itself.
   8  */
   9
  10 #include "thread_intern.h"
  11
  12 #include <exec/semaphores.h>
  13 #include <exec/memory.h>
  14 #include <proto/exec.h>
  15
  16 /*****************************************************************************
  17
  18     NAME */
  19         AROS_LH0(void *, CreateMutex,
  20
  21 /*  SYNOPSIS */
  22
  23 /*  LOCATION */
  24         struct ThreadBase *, ThreadBase, 10, Thread)
  25
  26 /*  FUNCTION
  27         Creates a mutual exclusion device (aka lock).
  28
  29     INPUTS
  30         None.
  31
  32     RESULT
  33         The newly created mutex, or NULL if a mutex couldn't be created.
  34
  35     NOTES
  36
  37     EXAMPLE
  38         Mutex mutex = CreateMutex();
  39
  40     BUGS
  41
  42     SEE ALSO
  43         DestroyMutex(), LockMutex(), TryLockMutex(), UnlockMutex()
  44
  45     INTERNALS
  46         Mutexes are implemented as thin wrappers around Exec semaphores.
  47
  48 *****************************************************************************/
  49 {
  50     AROS_LIBFUNC_INIT
  51
  52     struct SignalSemaphore *sem;
  53
  54     if ((sem = (struct SignalSemaphore *) AllocMem(sizeof(struct SignalSemaphore), MEMF_PUBLIC)) == NULL)
  55         return NULL;
  56
  57     InitSemaphore(sem);
  58
  59     return (void *) sem;
  60
  61     AROS_LIBFUNC_EXIT
  62 } /* CreateMutex */