rom/exec/obtainsemaphoreshared.c

   1 /*
   2     Copyright © 1995-2011, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Get a shared lock on a semaphore.
   6     Lang: english
   7 */
   8
   9 #include <exec/semaphores.h>
  10 #include <aros/atomic.h>
  11
  12 #include "exec_intern.h"
  13 #include "exec_util.h"
  14 #include "semaphores.h"
  15
  16 #define CHECK_INITSEM 1
  17
  18 /*****************************************************************************/
  19 #undef  Exec
  20 #ifdef UseExecstubs
  21 #    define Exec _Exec
  22 #endif
  23
  24 /*  NAME */
  25         #include <proto/exec.h>
  26
  27         AROS_LH1(void, ObtainSemaphoreShared,
  28
  29 /*  SYNOPSIS */
  30         AROS_LHA(struct SignalSemaphore *, sigSem, A0),
  31
  32 /*  LOCATION */
  33         struct ExecBase *, SysBase, 113, Exec)
  34
  35 /*  FUNCTION
  36         Get a shared lock on a semaphore. If the lock cannot be obtained
  37         immediately this function waits. There may be more than one shared
  38         locks at the same time but only one exclusive one. An exclusive
  39         lock prevents shared locks. Shared locks are released with
  40         ReleaseSemaphore().
  41
  42     INPUTS
  43         sigSem - Pointer to semaphore structure
  44
  45     RESULT
  46
  47     NOTES
  48         This function preserves all registers.
  49
  50     EXAMPLE
  51
  52     BUGS
  53
  54     SEE ALSO
  55         ReleaseSemaphore()
  56
  57     INTERNALS
  58
  59 *****************************************************************************/
  60 {
  61 #undef Exec
  62
  63     AROS_LIBFUNC_INIT
  64
  65     struct TraceLocation tp = CURRENT_LOCATION("ObtainSemaphoreShared");
  66
  67     InternalObtainSemaphore(sigSem, NULL, &tp, SysBase);
  68
  69     AROS_LIBFUNC_EXIT
  70 } /* ObtainSemaphoreShared */