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Subject: inline asm question..
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Date: Tue, 15 Apr 1997 04:43:37 -0500
From: Chris Csanady <ccsanady@nyx.pr.mcs.net>
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I am trying to create an inline asm function, and was wondering if someone 
might help.  I am getting quite frustrated with all of the cryptic gcc/as
commands, and still have no clue as to how it translates into instructions.

All I wanted to do was to make the below inline function generate the
following code.  (It is a piece from one of Van Jacobsons mails..)  I
realize this is for sparc, but it really doesnt matter..

    /* NB - ocadd is an inline gcc assembler function */
    cksum = ocadd(ocadd(ocadd(ocadd(cksum, seq), ack), flg), sum);


    addcc %l3,%o0,%o3
    addxcc %l4,%o3,%o3
    addxcc %l2,%o3,%o3
    addxcc %l0,%o3,%o3

Pretty much all it does is add with carry.  Simple, eh?  I have been far
from sucessful at getting gcc to produce code this concise.  First of all,
its never really inline--always "call"s a subroutine.  Secondly, the
function always manipulates the stack pointer and pushes various other
things around.  The above becomes more than an order of magnitude larger..

So, how on earth does one get rid of all the associated overhead of my
supposedly inline function?  If anyone would care to comment, or even
post the 2 lines of code, I would really appreciate it.  I'd like to do
some more useful stuff, but I can never get around all the little cryptic
semantics of inlines and asms and such.

Thanks,
Chris Csanady