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Re: Image scaling performance

From: Vladimir 'φ-coder/phcoder' Serbinenko
Subject: Re: Image scaling performance
Date: Wed, 25 Feb 2015 19:56:55 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.4.0

On 25.02.2015 19:46, Michael Zimmermann wrote:
oh ok so linux's div/mod/... assembler is as slow/fast as grub's code?
Linux uses armv5>= ifdefs. Maybe we could optimized things a little :)
About scale_nn,
amarullz( wrote a
optimized version without divs:

Please try my patch (reattached here after minor fixes). The patch by anonymous source, sent by third-party through pastebin isn't acceptable from legal perspective
this code works a little faster. I'm still questioning the efficiency
math operations because on slow devices there are other bottlenecks of
the same kind(like de/compression).

On Wed, Feb 25, 2015 at 7:41 PM, Vladimir 'phcoder' Serbinenko
<address@hidden> wrote:
ARMv7 doesn't mandate div instructions. It's a separate flag in features.
GRUB supports earlier CPUs as well and we use them for testing. My only test
machine is armv6

Le 2015-02-25 19:38, "Michael Zimmermann" <address@hidden> a écrit

Why u think the native div code would crash on most devices? I support
ARMv7+ only anyway.

On Wed, Feb 25, 2015 at 5:23 PM, Leif Lindholm <address@hidden>
On Wed, Feb 25, 2015 at 03:45:40PM +0000, Leif Lindholm wrote:
Some technical info:
Linaro GCC 4.9

I don't see any calls to any of the __aeabi helpers generated for this
file with current head. Which specific Linaro toolchain are you using?
(mine is"Linaro GCC 4.9-2014.09").

Scratch that, I do see them. Just failing to drive the tools properly.


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