Re: Problem with ARM port and pow() function

[Fau Marz <faumarz at libero dot it>]

Alle 19:56, mercoledì 10 ottobre 2007, Fau Marz ha scritto:

> I am using newlib with gcc in an ARM7 cross compiling toolchain 
> (arm-elf-gcc) and I've found a problem in using the pow(x,y) function.
> 
> The problem is like that: when in pow(x,y) the "y" factor is an integer, 
> there is no problem. But when the "y" factor is a double or float (for 
> example "2.1") there is a data exception and the program hangs. Crash.

I've done some tests, and I can't understand what's wrong.
It seems that the problem is in the e_pow.c file, the line:

p_l = (y-y1)*t1+y*t2;

It seems that t1 contains a too big variable, causing overflow.

I can't understand... I've done a lot of tests with compilation options 
because I supposed it was a BIG_ENDIAN/LITTLE_ENDIAN problem, but I have 
always the same behaviour.

Maybe it's a linking problem of my project (not in newlib), but I can't 
understand it.
If you have any idea, please tell me.

Thank you for your attenction, even if this is probably not a strictly newlib 
problem....

I've tried also the CodeSourcery arm-none-eabi pre-built toolchain, and the 
problem is the same.


Regards,

Fausto

-- 
Faumarz