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

From: Joerg Wunsch
Subject: Re: [avr-gcc-list] code for 90s4433 is using SPH
Date: Thu, 20 Feb 2003 10:39:56 +0100 (MET)

Volkmar Dierkes <address@hidden> wrote:

> The 4433 has only a single byte for the stack pointer because of its
> limited ram. But I am wondered that the generated code is using SPH.

The compiler only distinguishes four different AVR "architectures",
avr2 through avr5.  Since even the smallest (avr2) has devices with
more than 256 bytes of RAM, the compiler always generates 16-bit stack
pointer operations.  Use -mtiny-stack to avoid this.

The only file that is really device specific is the gcrt1.o file.

> In the datasheet is only SPH defined with reserved, but no 
> hint that it is always zero.

It obviously is.  The library has to rely on it in many places,
otherwise we'd need a separate library file for each device.  Right
now, we have a separate library file for each AVR architecture.

(There's also an avr1 architecture, but it doesn't have C language
support.  Among others, the AT90S1200 belongs to it.)

J"org Wunsch                                           Unix support engineer
address@hidden        http://www.interface-systems.de/~j/

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