[Speex-dev] Shift count warning messages

[Jim Crichton]

I looked back at my old C55 EC build, and I had the same warning in mdf.c 
which Mike found.  The assembly code did have a valid shift, and this build 
did cancel echo.

When I built with the SVN head, I saw the errors in kiss_fft.c also.  The 
assembly there also has valid shifts.

So, I suspect that these warnings do not indicate a real problem.  It might 
be interesting to break down the offending lines into a sequence of simpler 
instructions, to see if the compiler can be placated in that way.

- Jim

----- Original Message ----- 
From: "Jean-Marc Valin" <jean-marc.valin at usherbrooke.ca>
To: "Jim Crichton" <jim.crichton at comcast.net>
Cc: "Michael Jacobson" <Michael.Jacobson at ultratec.com>; <speex-dev at xiph.org>
Sent: Tuesday, January 22, 2008 4:00 PM
Subject: Re: [Speex-dev] Shift count warning messages


> 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
>>>
>>>
>>>
>>> ------------------------------------------------------------------------
>>>
>>>
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>>> list Speex-dev at xiph.org
>>> http://lists.xiph.org/mailman/listinfo/speex-dev
>>
>>
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