Date: Wed, 12 Nov 1997 17:21:08 -0800 (PST)
Message-Id: <199711130121.RAA04349@adit.ap.net>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
To: Jan Hubicka <hubicka AT atrey DOT karlin DOT mff DOT cuni DOT cz>
From: Nate Eldredge <eldredge AT ap DOT net>
Subject: Re: Unoptimal implementation of pc.h
Cc: djgpp AT delorie DOT com
Precedence: bulk

At 08:38  11/12/1997 +0100, Jan Hubicka wrote:
>> At 05:23  11/11/1997 +0100, Jan Hubicka wrote:
>> >Hi
>> >In file inlines/pc.h in those outport* inport* functions are port always
>> threaded as "d" (edx)
>> >but you should also use an constant port "N"
>> >so I think using "Nd" instead of "d" should save few instrucions and
>> register or not?
>> No. The "N" constraint is only intended for the compiler. It doesn't make
>> sense to use it for inline asm, since the compiler doesn't know
>> ahead-of-time what port will be written to. Its only choice is to load the
>> port number into the dx register.
>> (Also, the constant-port form of `in'/`out' only works for port numbers up
>> to 0xFF, which is pretty useless.)
>Well, I tries this "Nd" constraint and it worked as I expected.
>out(20,20); used constant
>out(256,20); used edx
>and variables used edx...whats bad on that?
Oh really! Wow! I didn't think the compiler was that smart. I need to not
underestimate GCC anymore. :)
In that case, maybe it is a good idea. Anyone else think so?

Nate Eldredge
eldredge AT ap DOT net