[Speex-dev] Shift count warning messages

[Jean-Marc Valin]

Jim Crichton a écrit :
> 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 at 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 at 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 écrit :
>> 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
>> 
>> 
>> 
>> ------------------------------------------------------------------------
>> 
>> 
>> _______________________________________________ Speex-dev mailing
>> list Speex-dev at xiph.org 
>> http://lists.xiph.org/mailman/listinfo/speex-dev
> 
> 
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