Re: [Discuss-gnuradio] gnuradio c++ code structure question

[mehmet kabasakal]

Hi Martin,

As you guess, i use gr_sync_block.
But i don't use vector input items, i mean the input of the block is
streaming points.
Do i still have noutput_items * 2048 buffer size?

Mehmet.

2011/3/7, Martin Braun <address@hidden>:
> Hi Mehmet,
>
> you've omitted some crucial parts of your code.
> I'm guessing you've made your block a gr_sync_block.
>
> It's easiest if your input items are vectors. In that case, your input
> buffer (input_items) will contain noutput_items * 2048 float values.
> Then, just process your data on whole blocks.
>
> The operation you describe seems pretty simple. You can probably set it
> up with a couple of existing blocks without having to write any code at
> all, although your method is surely more efficient (in terms of CPU
> load, not development time).
>
> MB
>
> On Mon, Mar 07, 2011 at 03:56:04PM +0200, mehmet kabasakal wrote:
>> Hi everyone,
>>
>> I am trying to develop a frame based structure for gnuradio block on c++.
>> The frame size will be 2048 point and i will calculate the normalized
>> amplitude for every frame i.e.
>>
>> ma = sum(every 2048 points)/2048;
>> normalized amplitude = all 2048 points / ma;
>>
>> i wrote a code that gives me the desired result under "work" function;
>>
>>
>>
>> int
>> gr_gama_maks_ff::work (int noutput_items,
>>                      gr_vector_const_void_star &input_items,
>>                      gr_vector_void_star &output_items)
>> {
>>   const float *in = (const float *) input_items[0];
>>   float *out = (float *) output_items[0];
>>   float ma = 0.0;
>>   float acn[noutput_items], an[noutput_items];
>>   int C = 2048;
>>   int a = 0;
>>   int count = 0;
>>
>>   for (int i = 0; i < noutput_items; i++){
>>     ma = 0.0;
>>     for (int m = a*C; m < a*C+C ; m++) {
>>      ma += in[m]/C;  
>>     }
>>
>>     an[i] = in[i]/ma;
>>     acn[i] = an[i]-1;
>>     out[i] = acn[i]*d_k;
>>
>>    if ((i+1) % C == 0) {
>>     a = a + 1;
>>    }
>>   }
>>
>>
>>
>> As you see i didn't keep a 2048 point array, i just find the sum of
>> 2048 points and then use it for the output (an[i]= in[i]/ma). But i
>> couldn't figure out how this happens. I mean the while index "i = 1"
>> in the first for loop, i can reach the i+2047th sample in the second
>> for loop.
>>
>> Is there a buffer for every block in gnuradio. If yes what is the size
>> of the buffer?
>>
>> I hope i would explain it clear.
>>
>> Mehmet.
>>
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>> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>
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