Problem with div (1.9.0, arm7tdmi)

[Lewin A.R.W. Edwards]

> > I have been experiencing a very odd bug in div() from newlib 1.9.0 on an
> > arm7tdmi target (using gcc 2.95.2/cygwin). The manifestation of the bug is
> > that subroutines will spontaneously return out of the middle of the
> > routine, or hang, especially on nested div calls. I eventually tracked 
> down
>
>I'm not sure what you mean by "nested div calls" - do you force div() to
>call itself recursively or something strange?

I mean something like:

y = div(a,div(b,c).rem).rem;

This kind of arithmetic is used a lot in filesystems :) The particular code 
where I hit the problem worst was in my CHS<->LBA conversion.

>I'm not an ARM guy, but this sounds like a struct "return by value" problem.
>You need to look at the generated assembly and see if the stack space is
>being reclaimed before the value is used, or something of the sort.

Very similar to Ingo's suggestion; thanks. I'll poke a bit deeper. Just 
wondering if this was a known problem with newlib (it hasn't bitten me on 
other platforms, which is why I was wondering - in fact this code is more 
or less a direct recompile of some old PA-RISC code I wrote).


-- Lewin A.R.W. Edwards
Embedded Engineer, Digi-Frame Inc.
Work: http://www.digi-frame.com/
Tel (914) 937-4090 9am-6:30pm M-F ET
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