Re: [Discuss-gnuradio] Bug in digital::glfsr_source_b

Marcus -

Did you ever hear anything back regarding the signed representation? If not, I'd like to go ahead and get a PR filed.

Cheers,

Ben

On Tue, Aug 9, 2016 at 3:18 AM, Marcus Müller <marcus.mueller@ettus.com> wrote:

Hi Eugene,

that sounds like a bug, and a fix, indeed!

I'd immediately go ahead and just replace the int by uint32_t (which happens to be the thing we want to use here, considering the degree self-limits to 32).

But: I know this has been around 0.75 eterneties; Michael even fixed some compiler warning in glfsr.cc last year; I want to be sure we're not breaking anything hence I'm, hereby asking around:

was there a rationale behind having signed intage here?

Best regards,

Marcus

On 09.08.2016 02:29, Eugene Grayver wrote:

Note: It is, of course, possible to trick the blocks into working by passing in negative values (n - 2**32), but it is not elegant.

________________________

Eugene Grayver, Ph.D.
Aerospace Corp., Sr. Eng. Spec.
Tel: 310.336.1274
________________________

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From: Eugene Grayver
Sent: Monday, August 8, 2016 5:22 PM
To: discuss-gnuradio@gnu.org
Subject: Re: Bug in digital::glfsr_source_b

 

Note: same issue with descrambler_bb and scrambler_bb.  The digital.lfsr block is correct.

________________________

Eugene Grayver, Ph.D.
Aerospace Corp., Sr. Eng. Spec.
Tel: 310.336.1274
________________________

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From: Eugene Grayver
Sent: Monday, August 8, 2016 2:47 PM
To: discuss-gnuradio@gnu.org
Subject: Bug in digital::glfsr_source_b

 

I found a minor (?) bug in glfsr_source_b and _f, and in glfsr.h.  The input types for mask and seed should be 'unsigned int', not 'int'.  Currently it does not allow 32-bit values, only 31-bit values.  While somebody is fixing that, they should also make 'length' an optional input to have the LFSR restart after fewer than 2^degree outputs.

________________________

Eugene Grayver, Ph.D.
Aerospace Corp., Sr. Eng. Spec.
Tel: 310.336.1274
________________________

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