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Path: utzoo!linus!decvax!genrad!grkermit!masscomp!kobold!tjt
From: tjt@kobold.UUCP (T.J.Teixeira)
Newsgroups: net.micro.68k
Subject: Re: nargs
Message-ID: <226@kobold.UUCP>
Date: Thu, 29-Dec-83 18:24:07 EST
Article-I.D.: kobold.226
Posted: Thu Dec 29 18:24:07 1983
Date-Received: Sat, 31-Dec-83 04:27:22 EST
References: <363@sii.UUCP>, <2113@fortune.UUCP>
Organization: Masscomp, Westford, MA
Lines: 24

Another stack adjustment instruction is:

	ADDW	#n*4,SP

Remember, the 68000 will sign extend any operand applied to an address
register.

This has the same time/space performance as the

	LEA	n*4(SP),SP

instruction mentioned by sii!mem (Mark Mallet), and *is* actually
generated by the Masscomp C compiler.

Of course, all the other caveats apply, leading to the unfortunate
result of if you *really* want it done right, you have to do it
yourself.  Of course, since it is easy to miscount arguments, and the C
language (and most runtime systems) won't provide it for you, you could
try a special "end-of-argument-list" value (e.g. 0 in execv and
variants).

-- 
	Tom Teixeira,  Massachusetts Computer Corporation.  Westford MA
	...!{ihnp4,harpo,decvax,ucbcad,tektronix}!masscomp!tjt   (617) 692-6200