Re: [B2-devel] Fixes for the generic FPU emulation core

[<gb...@di...>]

Hi,

> Yes, the CVS sources still have that problem. I applied Lauri's changes to
> uae_cpu/fpp.cpp, but nothing more.

I have just tried to remove the assembly type conversion functions,
especially (only in fact) to_single() and restore the original one in C
from uae_cpu/fpp.cpp. Scrollbars stopped to work again.

The problem is that there is no check for NaN, Inf and Zero. So, if the
exponent is set to the maximum (possibly a NaN of Inf), doing exponent +
FP_DOUBLE(or EXTENDED)_EXP_BIAS - FP_SINGLE_EXP_BIAS without extra tests
is not correct.

I fixed it by assigning each part of the floating-point value through a
fp_single_shape type (32-bit float).

Maybe something like hereunder mentioned would work as well:

function::to_single()

union {
  fp_single as_single;
  uae_u32   as_uint32;
} fp_loader;

fp_loader.as_uint32 = byteswap(value);
return (fp_extended)fp_loader.as_single;

Hmm, actually, I tried to apply it on the CVS sources, this didn't work.
But it does with my current changes in fpu_ieee.cpp. i.e. only
to_single() is reimplemented in C++.

BTW, I also got inspired from binutils-2.x.x/libiberty/floatformat.c.
Unfortunately, the diffs I tried did not work...

PS: I reuploaded the file fpu_ieee.cpp on my website.

PPS: Christian, would it be possible to tell the mailing-list manager
(or whatsoever) to automatically add a Reply-To: <this_list> field ?

Thanks.
-- 
Gwenolé Beauchesne