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From: Dirk Behme <dirk.behme@gmail.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] [RFC PATCH] ARM: byteorder: add optimized swab16 and swab32
Date: Fri, 10 May 2013 19:42:41 +0200	[thread overview]
Message-ID: <518D3191.7060205@gmail.com> (raw)
In-Reply-To: <yw1xr4hevkmw.fsf@unicorn.mansr.com>

Am 10.05.2013 18:56, schrieb M?ns Rullg?rd:
> Dirk Behme <dirk.behme@gmail.com> writes:
>
>> Use the specialized ARM instructions for swapping 16 and 32 bit values
>> instead of using the generic ones from include/linux/byteorder/swab.h.
>>
>> The x86 version in arch/x86/include/asm/byteorder.h was taken as an
>> example for this.
>>
>> E.g. for the mx6qsabrelite target this results in ~4k less code.
>
> Which compiler are you using?

An older gcc 4.4.4 version.

> GCC 4.5 and later recognises the byteswap
> pattern and emits these instructions automatically.  This gives better
> code than the inline asm since it allows the compiler to do proper
> instruction scheduling, and in the 16-bit case it avoids extraneous
> masking.

Thanks,

Dirk

  reply	other threads:[~2013-05-10 17:42 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-05-10 16:23 [U-Boot] [RFC PATCH] ARM: byteorder: add optimized swab16 and swab32 Dirk Behme
2013-05-10 16:56 ` Måns Rullgård
2013-05-10 17:42   ` Dirk Behme [this message]
2013-05-11  0:05     ` Wolfgang Denk

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