From: Antti Palosaari <crope@iki.fi>
To: Mauro Carvalho Chehab <mchehab@osg.samsung.com>,
Prashant Laddha <prladdha@cisco.com>
Cc: hverkuil@xs4all.nl,
Linux Media Mailing List <linux-media@vger.kernel.org>,
Hans Verkuil <hans.verkuil@cisco.com>
Subject: Re: [PATCH 1/6] Use LUT based implementation for (co)sine functions
Date: Mon, 15 Dec 2014 15:30:04 +0200 [thread overview]
Message-ID: <548EE25C.4060808@iki.fi> (raw)
In-Reply-To: <20141215111321.7602a7b9@recife.lan>
On 12/15/2014 03:13 PM, Mauro Carvalho Chehab wrote:
> Em Mon, 15 Dec 2014 14:49:17 +0530
> Prashant Laddha <prladdha@cisco.com> escreveu:
>
>> Replaced Taylor series calculation for (co)sine with a
>> look up table (LUT) for sine values.
>
> Kernel has already a LUT for sin/cos at:
> include/linux/fixp-arith.h
>
> The best would be to either use it or improve its precision, if the one there
> is not good enough.
I looked that one when made generator. It has poor precision and it uses
degrees not radians. But surely it is correct practice improve existing
than introduce new.
regards
Antti
--
http://palosaari.fi/
next prev parent reply other threads:[~2014-12-15 13:30 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1418635162-8814-1-git-send-email-prladdha@cisco.com>
2014-12-15 9:19 ` [PATCH 1/6] Use LUT based implementation for (co)sine functions Prashant Laddha
2014-12-15 9:24 ` Improvements in (co)sine generation in vivid sdr Prashant Laddha (prladdha)
2014-12-15 13:13 ` [PATCH 1/6] Use LUT based implementation for (co)sine functions Mauro Carvalho Chehab
2014-12-15 13:30 ` Antti Palosaari [this message]
2014-12-16 6:41 ` Prashant Laddha (prladdha)
2014-12-16 10:45 ` Mauro Carvalho Chehab
2014-12-16 11:40 ` Mauro Carvalho Chehab
2014-12-16 15:30 ` [RFC PATCH] fixp-arith: replace sin/cos table by a better precision one Mauro Carvalho Chehab
2014-12-17 8:17 ` Prashant Laddha (prladdha)
2014-12-17 13:42 ` [RFC PATCHv2] " Mauro Carvalho Chehab
2014-12-17 19:11 ` Prashant Laddha (prladdha)
2014-12-17 21:54 ` Mauro Carvalho Chehab
2014-12-15 9:19 ` [PATCH 2/6] Vivid sine gen: Optimization for sine LUT size Prashant Laddha
2014-12-15 9:19 ` [PATCH 3/6] Vivid sine gen: Refactor get_sin_val () Prashant Laddha
2014-12-15 9:19 ` [PATCH 4/6] Vivid sine gen: Renamed SIN_TAB_SIZE to SIN_LUT_SIZE Prashant Laddha
2014-12-15 9:19 ` [PATCH 5/6] Vivid: Increased precision for (co)sine computation Prashant Laddha
2014-12-15 9:19 ` [PATCH 6/6] Vivid SDR: Modified equation used for generating FM Prashant Laddha
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