workbench/libs/thread/lockmutex.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 <proto/exec.h>
  14 #include <assert.h>
  15
  16 /*****************************************************************************
  17
  18     NAME */
  19         AROS_LH1(void, LockMutex,
  20
  21 /*  SYNOPSIS */
  22         AROS_LHA(void *, mutex, A0),
  23
  24 /*  LOCATION */
  25         struct ThreadBase *, ThreadBase, 12, Thread)
  26
  27 /*  FUNCTION
  28         Locks a mutex. If the lock is already held, this function blocks.
  29
  30     INPUTS
  31         mutex - mutex to lock.
  32
  33     RESULT
  34         This function always succeeds.
  35
  36     NOTES
  37
  38     EXAMPLE
  39         LockMutex(mutex);
  40
  41     BUGS
  42
  43     SEE ALSO
  44         CreateMutex(), DestroyMutex(), TryLockMutex(), UnlockMutex()
  45
  46     INTERNALS
  47         Mutexes are implemented as thin wrappers around Exec semaphores.
  48
  49 *****************************************************************************/
  50 {
  51     AROS_LIBFUNC_INIT
  52
  53     assert(mutex != NULL);
  54
  55     ObtainSemaphore((struct SignalSemaphore *) mutex);
  56
  57     AROS_LIBFUNC_EXIT
  58 } /* LockMutex */