Re: [Discuss-gnuradio] Help me help myself

[Philip Balister]

On 12/22/2014 06:42 PM, Marcus D. Leech wrote:
> On 12/22/2014 06:37 PM, Richard Bell wrote:
>> Hi all,
>>
>> The goal of this email is to learn how to find answers using available
>> resources on my own in the future. To do this, I will explain what
>> I've done to try and find the answer and then I hope someone can tell
>> me how to finish the process so that next time I can do it on my own.
>>
>> I'm working through the details of the MM Timing Recovery block. In
>> the process of doing this I've come across the following line in source:
>>
>> d_omega = d_omega_mid + gr::branchless_clip(d_omega-d_omega_mid,
>> d_omega_lim);
>>
>> I don't know what gr::branchless_clip does, so I started looking for
>> answers on google and the gnuradio API manual. In the manual, I find
>> this:
>>
>> http://gnuradio.org/doc/doxygen/namespacegr.html#ace35e8c3e3ad45a5100217d2b6826e1b
>>
>>
>> but that doesn't tell me what it does. I can't find anymore reference
>> to branchless_clip then this.
>>
>> From the source code, I don't know how to track down the reference.
>> I've searched my laptop for branchless_clip, but I get no returns.
>>
>> So the question is, how do I find what branchless_clip does in the MM
>> Timing Recovery block? I care more about the "how do I find" part of
>> the question then the actual answer, though I do want the actual answer.
>>
> I used the following "find" command:
> 
> find gnuradio -name "*.*" -exec grep -H branchless_clip '{}' ';'
> 
> And found the definition in:
> 
> gnuradio/gnuradio-runtime/include/gnuradio/math.h: 
> branchless_clip(float x, float clip)

I'm not as smart as Marcus, so I googled "branchless clip",

http://stackoverflow.com/questions/427477/fastest-way-to-clamp-a-real-fixed-floating-point-value

Philip

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