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Date: Sat, 11 Dec 2004 10:24:40 -0500
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From: DJ Delorie <dj AT delorie DOT com>
To: djgpp AT delorie DOT com
In-reply-to: <b3Aud.18735$Zk.327000@twister2.libero.it> (message from Carlo on
	Sat, 11 Dec 2004 10:34:47 GMT)
Subject: Re: why inportb and outportb are so time expensive ?
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> I have an application with a lot of inportb and outportb, most of the 
> time is spent to do these function calls.

Two things come to mind:

1. inportb and outportb are intended to be inlined.  Are you including
   the right header, and compiling with optimization, and have you
   verified that the instructions are inlined into a single opcode?
   You can check this with gdb (x/i) or objdump -d.

2. What peripherals are you talking to?  I/O requests to slow
   peripherals will require a delay in the I/O itself, which can add a
   significant delay to those opcodes.