[U-Boot] [PATCH V2] console: Implement pre-console buffer
Wolfgang Denk
wd at denx.de
Tue Aug 30 22:08:17 CEST 2011
Dear Mike Frysinger,
In message <201108301558.08010.vapier at 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
--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
"Maintain an awareness for contribution -- to your schedule, your
project, our company." - A Group of Employees
More information about the U-Boot
mailing list