Re: [linuxdc-dev]Floating point problems - Dreamcast 2.4.10-pre6 kernel

[M. R. B. <mr...@0x...>]

* Adrian McMenamin <ad...@mc...> on Thu, Dec 27, 2001:

> I have been working to make/port a decent mp3 player for the Dreamcast no=
w=20
> that there is a sound driver.
>=20
> I have built mpg123 with these options:
>=20
> dream:
> 	$(MAKE) CC=3Dsh4-linux-gcc LDFLAGS=3D \
> 	OBJECTS=3D'decode.o dct64.o audio_oss.o' \
> 	CFLAGS=3D'-DREAL_IS_FLOAT -DLINUX -Wall -O2 \
> 		-DOSS \
> 		-fomit-frame-pointer -funroll-all-loops \
> 		-finline-functions -ffast-math' \
> 		mpg123-make
>=20
> but this always generates a floating point exception at run time.
>=20

I'm not to keen on how the flags function for the SH backend of GCC (maybe
NIIBE-san knows?) but I always thought -ffast-math was a i386-based (not
necessarily specific) optimization.  I don't think it's wise to use it here
=2E.. although it may be a no-op.  Only a read through GCC's source will
confirm that.

>=20
> Incuidentally with -DREAL_IS_FLOAT switched off then there is no fp excep=
tion=20
> but the program outputs static.
>=20

Have you tried with -m4-single-only?  It generates FP code conforming to
what its name implies.

> So: the questions are - is this a known problem, has it been fixed in lat=
er=20
> kernels or have I just got it wrong?
>=20

I don't see how it could be a kernel issue.

M. R.