linux-kernel - Re: [PATCH 3/4] Fix remaining big endian issue of hfcmulti

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Date:	Wed, 06 Aug 2008 07:45:53 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Karsten Keil <kkeil@...e.de>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, isdn4linux@...tserv.isdn4linux.de,
	"Andreas.Eversberg" <Andreas.Eversberg@...satel.de>
Subject: Re: [PATCH 3/4] Fix remaining big endian issue of hfcmulti

> static void
> my_out32(struct card *c, u_int offset, u-int data) 
> {
> 	if (c->mode == MMIO) {
> 		...
> 	} else {
> 		...
> 	}
> }
> 
> or use 2 function, one for the MMIO and one for the PIO model and then use
> indirect calls (like c->my_out32(...)) ?

The former is more ugly but slightly faster on some archs.

Indirect function calls tend to be slightly slower than an if / else
statement that can be more easily predicted by the processor.

But in the case of IOs, it's not going to be a big deal, -especially- if
you use the _rep forms for data transfers (and thus don't do an indirect
call for each read/write). So it's totally up to you.

Cheers,
Ben.

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