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Re: [avr-gcc-list] Transfer bit conserved by gcc?

From: Ruud Vlaming
Subject: Re: [avr-gcc-list] Transfer bit conserved by gcc?
Date: Mon, 22 Sep 2008 00:09:16 +0200
User-agent: KMail/1.9.1

On Sunday 21 September 2008 22:22, you wrote:

> T-bit is used by avr-gcc for internal purpose, the same way as temp reg (r0)
> and cannot be used for storing value.
I see. I looked at it and i cannot get clear in which circumstances,
this is, but it does not really matter i suppose. Point is, you cannot destroy
the value of the Tbit at your liking, although i never saw the Tbit being used 
in my code by gcc.

And how about the H flag? The Half carry is produced by a lot of instructions,
but i never saw the compiler test for it,or make use of it. I looked the avr 
directory over for H flag tests or direct H flag manipulating functions 
(seh, clh, brhc, brhs) and found none.

You would really help me if you know more on this.


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