From: Pavel Roskin <proski@gnu.org>
To: The development of GRUB 2 <grub-devel@gnu.org>
Subject: Re: Endianness macros capitalization
Date: Wed, 09 Jul 2008 02:47:27 -0400 [thread overview]
Message-ID: <1215586047.31230.27.camel@dv> (raw)
In-Reply-To: <4873AC32.3060004@t-online.de>
On Tue, 2008-07-08 at 20:04 +0200, Christian Franke wrote:
> With old gcc versions without the "rol" optimization, even the 16 bit
> swap should be a function:
Or better yet, an asm statement.
We should consider optimized assembly vs function call. Even the 32-bit
swap could be shorter:
a: 86 c4 xchg %al,%ah
c: c1 c0 10 rol $0x10,%eax
f: 86 c4 xchg %al,%ah
11:
That's 7 bytes! And if written properly, it could work with any of the
registers that allow access to the lower two bytes (%eax, %ebx, %ecx and
%edx), thus giving more flexibility to the optimizer.
--
Regards,
Pavel Roskin
next prev parent reply other threads:[~2008-07-09 6:47 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-05 13:27 Endianness macros capitalization Javier Martín
2008-07-05 21:30 ` Pavel Roskin
2008-07-05 22:54 ` Javier Martín
2008-07-05 23:14 ` Pavel Roskin
2008-07-06 18:30 ` Robert Millan
2008-07-06 20:02 ` Javier Martín
2008-07-07 19:25 ` Christian Franke
2008-07-08 18:04 ` Christian Franke
2008-07-09 6:47 ` Pavel Roskin [this message]
2008-07-09 12:50 ` Christian Franke
2008-07-09 17:57 ` Pavel Roskin
2008-07-10 19:25 ` Christian Franke
2008-07-10 19:59 ` Pavel Roskin
2008-07-11 7:06 ` Jordi Mallach
2008-07-11 8:53 ` Pavel Roskin
2008-07-11 9:07 ` Pavel Roskin
2008-07-11 13:21 ` Christian Franke
2008-07-11 18:33 ` Pavel Roskin
2008-07-20 13:45 ` Christian Franke
2008-07-20 23:31 ` Pavel Roskin
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