rom/exec/initsemaphore.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Initialize a SignalSemaphore
   6     Lang: english
   7 */
   8
   9 #include "exec_intern.h"
  10 #include <exec/semaphores.h>
  11 #include <proto/exec.h>
  12
  13 /*****************************************************************************
  14
  15     NAME */
  16
  17         AROS_LH1I(void, InitSemaphore,
  18
  19 /*  SYNOPSIS */
  20         AROS_LHA(struct SignalSemaphore *, sigSem, A0),
  21
  22 /*  LOCATION */
  23         struct ExecBase *, SysBase, 93, Exec)
  24
  25 /*  FUNCTION
  26         Prepares a semaphore structure for use by the exec semaphore system,
  27         i.e. this function must be called after allocating the semaphore and
  28         before using it or the semaphore functions will fail.
  29
  30     INPUTS
  31         sigSem - Pointer to semaphore structure
  32
  33     RESULT
  34
  35     NOTES
  36         Semaphores are shared between the tasks that use them and must
  37         therefore lie in public (or at least shared) memory.
  38
  39     EXAMPLE
  40
  41     BUGS
  42
  43     SEE ALSO
  44
  45     INTERNALS
  46
  47 *****************************************************************************/
  48 {
  49     AROS_LIBFUNC_INIT
  50
  51     /* Clear list of wait messages */
  52     sigSem->ss_WaitQueue.mlh_Head     = (struct MinNode *)&sigSem->ss_WaitQueue.mlh_Tail;
  53     sigSem->ss_WaitQueue.mlh_Tail     = NULL;
  54     sigSem->ss_WaitQueue.mlh_TailPred = (struct MinNode *)&sigSem->ss_WaitQueue.mlh_Head;
  55
  56     /* Set type of Semaphore */
  57     sigSem->ss_Link.ln_Type = NT_SIGNALSEM;
  58
  59     /* Semaphore is currently unused */
  60     sigSem->ss_NestCount = 0;
  61
  62     /* Semaphore has no owner yet */
  63     sigSem->ss_Owner = 0;
  64
  65     /* Semaphore has no queue */
  66     sigSem->ss_QueueCount = -1;
  67
  68 #if defined(__AROSEXEC_SMP__)
  69     EXEC_SPINLOCK_INIT(&sigSem->ss_MultipleLink.sr_SpinLock);
  70 #endif
  71
  72     AROS_LIBFUNC_EXIT
  73 } /* InitSemaphore */
  74