rom/exec/vacate.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Release a lock obtained with Procure().
   6     Lang: english
   7 */
   8 #include <exec/lists.h>
   9 #include <exec/semaphores.h>
  10 #include <proto/exec.h>
  11 #include "semaphores.h"
  12 #include "exec_intern.h"
  13
  14 /*****************************************************************************
  15
  16     NAME */
  17
  18         AROS_LH2(void, Vacate,
  19
  20 /*  SYNOPSIS */
  21         AROS_LHA(struct SignalSemaphore  *, sigSem, A0),
  22         AROS_LHA(struct SemaphoreMessage *, bidMsg, A1),
  23
  24 /*  LOCATION */
  25         struct ExecBase *, SysBase, 91, Exec)
  26
  27 /*  FUNCTION
  28         Release a lock obtained with Procure. This will even work if the
  29         message is not yet replied - the request will be cancelled and the
  30         message replied. In any case the ssm_Semaphore field will be set to
  31         NULL.
  32
  33     INPUTS
  34         sigSem - Pointer to semaphore structure.
  35         bidMsg - Pointer to struct SemaphoreMessage.
  36
  37     RESULT
  38
  39     NOTES
  40
  41     EXAMPLE
  42
  43     BUGS
  44
  45     SEE ALSO
  46         Procure()
  47
  48     INTERNALS
  49
  50 *****************************************************************************/
  51 {
  52     AROS_LIBFUNC_INIT
  53
  54     struct SemaphoreRequest *sr = NULL;
  55
  56     /* Arbitrate for the semaphore structure */
  57     Forbid();
  58     bidMsg->ssm_Semaphore = NULL;
  59
  60     /*
  61      *  Two cases, the request is in the list, which means it hasn't been
  62      *  granted, or the request is not in the list, in which case it has
  63      *  been granted. We need to check if the request is in the list.
  64      */
  65     ForeachNode(&sigSem->ss_WaitQueue, sr)
  66     {
  67         if (sr == (struct SemaphoreRequest *)bidMsg)
  68         {
  69             /* Found it. Remove it from the semaphore's waiting queue. */
  70             Remove(&bidMsg->ssm_Message.mn_Node);
  71             sigSem->ss_QueueCount--;
  72
  73             /* And reply the message. */
  74             ReplyMsg(&bidMsg->ssm_Message);
  75
  76             /* All done */
  77             Permit();
  78             return;
  79         }
  80     }
  81
  82     /* No, it must have been fulfilled. Release the semaphore and done. */
  83     ReleaseSemaphore(sigSem);
  84
  85     /* All done. */
  86     Permit();
  87     AROS_LIBFUNC_EXIT
  88 } /* Vacate */