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Re: [avr-gcc-list] code for 90s4433 is using SPH

From: Marek Michalkiewicz
Subject: Re: [avr-gcc-list] code for 90s4433 is using SPH
Date: Sun, 23 Feb 2003 19:37:01 +0100
User-agent: Mutt/1.4i

On Sun, Feb 23, 2003 at 07:09:09PM +0100, Volkmar Dierkes wrote:
> But another issue what happens at the time when accessing local 
> variables: The Y-register is loaded with SPH and SPL and an offset. 
> If tiny-stack is used, only SPL is valid, so YH should be loaded 
> with 0 instead of SPH. My opinion.

Well, but the non-existent SPH should read as zero anyway.
Or are there any devices where this is not true?

SPH doesn't have to be zero with -mtiny-stack.  On a device with 512
bytes of SRAM (0x60 ... 0x25f), SP could be initialized as 0x25f,
and -mtiny-stack can still be used as long as the stack never grows
below 0x200 (96 bytes of stack - reasonable for many applications).


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