rom/exec/getmsg.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Get a message from a message port.
   6     Lang: english
   7 */
   8 #include <aros/debug.h>
   9 #include <exec/execbase.h>
  10 #include <exec/ports.h>
  11 #include <aros/libcall.h>
  12 #include <proto/exec.h>
  13
  14 /*****************************************************************************
  15
  16     NAME */
  17
  18         AROS_LH1(struct Message *, GetMsg,
  19
  20 /*  SYNOPSIS */
  21         AROS_LHA(struct MsgPort *, port, A0),
  22
  23 /*  LOCATION */
  24         struct ExecBase *, SysBase, 62, Exec)
  25
  26 /*  FUNCTION
  27         Get a message from a given messageport. This function doesn't wait
  28         and returns NULL if the messageport is empty. Therefore it's
  29         generally a good idea to WaitPort() or Wait() on the given port first.
  30
  31     INPUTS
  32         port - Pointer to messageport
  33
  34     RESULT
  35         Pointer to message removed from the port.
  36
  37     NOTES
  38
  39     EXAMPLE
  40
  41     BUGS
  42
  43     SEE ALSO
  44         WaitPort(), PutMsg()
  45
  46     INTERNALS
  47
  48 ******************************************************************************/
  49 {
  50     AROS_LIBFUNC_INIT
  51
  52     struct Message *msg;
  53
  54     ASSERT_VALID_PTR(port);
  55
  56     /* Protect the message list. */
  57     Disable();
  58
  59     /* Get first node. */
  60     msg=(struct Message *)RemHead(&port->mp_MsgList);
  61
  62     /* All done. */
  63     Enable();
  64
  65     ASSERT_VALID_PTR_OR_NULL(msg);
  66     return msg;
  67     AROS_LIBFUNC_EXIT
  68 } /* GetMsg() */
  69