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From: guy@gorodish.UUCP
Newsgroups: comp.sys.ibm.pc,comp.lang.c
Subject: Re: Inline assembler in Microsoft C ????
Message-ID: <21211@sun.uucp>
Date: Tue, 16-Jun-87 13:32:53 EDT
Article-I.D.: sun.21211
Posted: Tue Jun 16 13:32:53 1987
Date-Received: Thu, 18-Jun-87 02:30:04 EDT
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Xref: utgpu comp.sys.ibm.pc:4251 comp.lang.c:2366

> >asm("<assembler code>");
> 
>    Isn't this spo'sta be apart of the "Standard C".  I seem to remember
> it being metioned in the K&R.

It is absolutely NOT supposed to be in standard C!

	1) One could imagine an implementation of C on a machine with
	   no "assembly language".

	2) Not all C compilers generate assembly language; it may be
	   very tricky to generate in-line assembly language with
	   some of them.

	3) Not all C compilers handle this in the same fashion.  The
	   VAX compiler, and a lot of other compilers, have the
	   syntax

		asm(string);

	   and just squirt the string into the generated code at that
	   point, *verbatim*.  Others permit you to define in-line
	   "functions" that take arguments, and have different code
	   generated depending on the addressing mode used to refer
	   to the arguments; in these versions, "asm" is used in the
	   *declaration*, and the "function" is *used* just like a
	   regular function.

	4) Standardizing this would have minimal effect on
	   portability, as should be obvious.

	5) The only place in the Reference Manual portion of K&R (the
	   only part that counts when talking about "Standard C")
	   where "asm" is mentioned merely states that some
	   implementations reserve "asm" as a keyword - not that all
	   of them do, and not that all of those that do use it in
	   the same way.
	Guy Harris
	{ihnp4, decvax, seismo, decwrl, ...}!sun!guy
	guy@sun.com