[Speex-dev] Shift count warning messages

Jean-Marc Valin
Tue, 22 Jan 2008 13:01:05 -0000

Jim Crichton a ?crit :
> I played briefly with the echo canceller on the C5509A back in May
> 2006.  I got the same compiler warnings, and sent a message to the
> list which included this:
>
> "I got several compiler warnings for "shift out of range" in
mdf.c,
> which I fixed by adding EXTEND32 to all of the SHL32s with 16 bit
> operands (st->frame_size in 6 places, st->wtmp2 in 1 place)."

Yes, I remember those and I'm pretty sure they're fixed now. I think the
problem comes from other changes I made later on, but I can't understand
what's wrong.

> I sent a patch with some fixes later that month, but I have not built
> the echo canceller since then (no room for it).  It is very likely
> that you are seeing the same issue, and the fix should be the same
> also.  The trickier problems are the ones that the compiler does not
> find.  EXTEND32 is usually the cure there also.
>
> Now that I look at mdf.c, though, W is declares as spx_word32_t, so
> there should not be a problem, unless spx_word32_t is being mapped to
> 16-bits.  That should not happen if you compile with CONFIG_TI_C54X
> defined.  This is odd.

In both cases, what I'm seeing is that the code does a shift right by
more than 16 bits. Is it possible that the C5x doesn't want to do that,
even for 32-bit operands? It's either that or there's a build problem
that causes the operands to be 16 bit instead of 32. This is indeed very
odd. Can you investigate a bit and check what the types are on both
sides of the shift?

Cheers,

	Jean-Marc




> - Jim
>
>
> ----- Original Message ----- From: Michael Jacobson To: Jean-Marc
> Valin Cc: speex-dev@xiph.org Sent: Tuesday, January 22, 2008 9:54 AM
> Subject: Re: [Speex-dev] Shift count warning messages
>
>
> yes, our DSP is 16 bit based, and if those bits of code aren't using
> 32 bit variables then yes that is what the warnings would be.  Does
> this mean that the preprocessor and echo canceller won't work as well
> because of this?
>
> -Mike
>
>>>> Jean-Marc Valin <jean-marc.valin@usherbrooke.ca> 01/18/08
8:42
>>>> PM >>>
>
> I think these warnings are due to your DSP being 16-bit and that bit
> of code not being 16-bit safe (unlike the encoder and decoder). Can
> you confirm?
>
> Jean-Marc
>
> Michael Jacobson a ?crit :
>> Hi, I'm using 1.2beta3 on a 5416 DSP
>>
>> I have been getting warning messages that say: "kiss_fft.c",
line
>> 142: warning: shift count is too large
>>
>>
>> I've noticed this on the echo canceller and the preprocessor.  all
>> pretty much related to these two lines of code:
>>
>> kiss_fft C_MUL4(scratch[0],Fout[m] , *tw1 );
>>
>> mdf.c st->wtmp2[i] >>
EXTRACT16(PSHR32(st->W[j*N+i],NORMALIZE_SCALEDOWN+16));
>>
>> Is there some kind of switch I was supposed to throw to not get
>> these messages? if not-are they hurting anything?
>>
>> -Mike
>>
>>
>>
>>
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>>
>>
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>> list Speex-dev@xiph.org
>> http://lists.xiph.org/mailman/listinfo/speex-dev
>
>
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