Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!samsung!uunet!cbmvax!jesup
From: jesup@cbmvax.commodore.com (Randell Jesup)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: ADCMD_ALLOCATE, ADIOF_NOWAIT => IOERR_ALLOCFAILED ?
Keywords: Audio channel allocation, PeekMsg()
Message-ID: <19056@cbmvax.commodore.com>
Date: 18 Feb 91 01:59:32 GMT
References: <1991Feb16.201228.524@indic.se>
Reply-To: jesup@cbmvax.commodore.com (Randell Jesup)
Organization: Commodore, West Chester, PA
Lines: 29

In article <1991Feb16.201228.524@indic.se> zap@indic.se (Jonas Petersson) writes:
>Second question: Which is the "most civilized" way to check whether a msg
>is waiting at a port or not? I currently use:
>
>#define WaitingMsg(port)    (port->mp_MsgList.lh_Head->ln_Type==NT_MESSAGE)

	From the Blue RKMs (slightly modified):

#define NOT_EMPTY(list)	((list)->lh_TailPred != (list))

	or

#define NOT_EMPTY	(NULL != (list)->lh_Head->ln_Succ)


	and

#define WaitingPort(port)	(NOT_EMPTY(&(port->mp_MsgList))

	The NOT_EMPTY macros work for any exec list, and with them WaitingPort
becomes trivial.  (I reversed the tests from the RKMs to test for not empty
instead of empty.)

-- 
Randell Jesup, Keeper of AmigaDos, Commodore Engineering.
{uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.commodore.com  BIX: rjesup  
The compiler runs
Like a swift-flowing river
I wait in silence.  (From "The Zen of Programming")  ;-)