Please see https://ctan.org/tex-archive/macros/xetex/generic/itrans?lang=en

which has

itrans-tamil.map	6 kB	2011-09-25
itrans-tamil.tec	1 kB	2011-09-25

Perhaps these could be modified for your input scheme.

ShreeDevi
____________________________________________________________
भजन - कीर्तन - आरती @ http://bhajans.ramparivar.com

On Wed, Jan 31, 2018 at 5:08 AM, David Jones <dmj@ams.org> wrote:

Does this fit the bill?

https://github.com/davidmjones/brahmic-maps

David.

---

From: XeTeX <xetex-bounces@tug.org> on behalf of Dominik Wujastyk <wujastyk@gmail.com>
Sent: Tuesday, January 30, 2018 6:30 PM
To: Indology; Unicode-based TeX for Mac OS X and other platforms
Subject: [XeTeX] XeTeX tec file for Tamil?

 

​Does anyone have a TECkit file for auto-transliterating standard Latin-script input to Tamil script output?​

Best,

Dominik Wujastyk

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