From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wolfgang Denk <wd@denx.de>
Date: Tue, 30 Aug 2011 22:08:17 +0200
Subject: [U-Boot] [PATCH V2] console: Implement pre-console buffer
In-Reply-To: <201108301558.08010.vapier@gentoo.org>
References: <1314620046-26187-3-git-send-email-graeme.russ@gmail.com>
	<CAPnjgZ1fXCCFDcwCWgZD7H-siVEV-H+Ks5TPeiT=nGS743fzcg@mail.gmail.com>
	<20110830195238.CC16118C46FE@gemini.denx.de>
	<201108301558.08010.vapier@gentoo.org>
Message-ID: <20110830200817.059BE18C46FE@gemini.denx.de>
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To: u-boot@lists.denx.de

Dear Mike Frysinger,

In message <201108301558.08010.vapier@gentoo.org> you wrote:
>
> > Please see my previous posting
> > (http://article.gmane.org/gmane.comp.boot-loaders.u-boot/106810)
> > 
> > I don't think 3 additional addembler instructions really play a big
> > role here.
>
> i'm pretty sure if you define CONFIG_PRE_CON_BUF_SZ as a power of 2 value, you 
> get nice & simple assembly code.  so if the generated code is undesirable,
> pick a CONFIG value that is power-of-2 ?

This was the test code I compiled:

---------------------------------------------
#define	CONFIG_SYS_TMP_CON_BUF_SZ	1024

int foo(int i)
{
	return i & (CONFIG_SYS_TMP_CON_BUF_SZ-1);
}

int bar(int i)
{
	return i % CONFIG_SYS_TMP_CON_BUF_SZ;
}
---------------------------------------------

So was actually checking for a power-of-2 value.

Best regards,

Wolfgang Denk

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