Problem trying to implement Reed Solomon encoder


#1

Hello,

I’m trying to create a GNU Radio block that carries out a Reed Solomon
coding based on the functions provided into the
directory /gnuradio-core/src/lib/reed-solomon.

As an example I have taken the block gr_encode_ccsds_27 that can be
found in the directory /gnuradio-core/src/lib/general since it uses the
functions implemented in /gnuradio-core/src/lib/viterbi.

Basically the aspect of my gr_rs_encoder_vbb.cc file is the following:

#ifdef HAVE_CONFIG_H
#include “config.h”
#endif

#include <gr_rs_encoder_vbb.h>
#include <gr_io_signature.h>

extern “C” {
#include “…/reed-solomon/fixed.h”
}

gr_rs_encoder_vbb_sptr
gr_make_rs_encoder_vbb()
{
return gr_rs_encoder_vbb_sptr(new gr_rs_encoder_vbb());
}

gr_rs_encoder_vbb::gr_rs_encoder_vbb()
: gr_sync_block(“rs_encoder_vbb”,
gr_make_io_signature(1, 1, (223)sizeof(char)),
gr_make_io_signature(1, 1, 255
sizeof(char)))
{
}

gr_rs_encoder_vbb::~gr_rs_encoder_vbb()
{
}

int
gr_rs_encoder_vbb::work(int noutput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items)
{
const unsigned char *in = (const unsigned char *)input_items[0];
unsigned char *out = (unsigned char *)output_items[0];

for (int i = 0; i < noutput_items; i++)
{
unsigned char *temp_first_element = out;
for (int j = 0; j < (223); j++)
*out++ = *in++;
ENCODE_RS(temp_first_element,–out);
}

return noutput_items;
}

I include the file fixed.h since I want to use the implementation of the
CCSDS standard (255,223).

When I execute make into the main folder of GNU Radio for compiling
everything I get the following ERROR message:

/bin/bash …/…/…/libtool --tag=CXX --mode=link g++ -g -O2 -Wall
-Woverloaded-virtual -pthread -o benchmark_dotprod_fff
benchmark_dotprod_fff.o
/home/apalomo/software/gnuradio-3.1.3/gnuradio-core/src/lib/libgnuradio-core.la
libtool: link: g++ -g -O2 -Wall -Woverloaded-virtual -pthread
-o .libs/benchmark_dotprod_fff
benchmark_dotprod_fff.o
/home/apalomo/software/gnuradio-3.1.3/gnuradio-core/src/lib/.libs/libgnuradio-core.so
/home/apalomo/software/gnuradio-3.1.3/omnithread/.libs/libgromnithread.so
-lrt /usr/lib/libfftw3f.so -lm -pthread
/home/apalomo/software/gnuradio-3.1.3/gnuradio-core/src/lib/.libs/libgnuradio-core.so:
undefined reference to encode_rs_8' collect2: ld returned 1 exit status make[4]: *** [benchmark_dotprod_fff] Error 1 make[4]: Leaving directory/home/apalomo/software/gnuradio-3.1.3/gnuradio-core/src/tests’
make[3]: *** [all-recursive] Error 1

It looks like I’m missing to include another file somewhere, but I have
no idea where.

Have anybody tried to implement this yet or anybody knows how I could
fix it?

Thank you very much.

Best regards.

Alvaro P.


#2

Hi,

Your problem is because you are not linking with the Reed/Solomon
library.

The problem is that you’ve wrapped the ‘#include <fixed.h>’ inside an
‘extern “C”’ block.

If you remove it then you’ll be one step closer to getting it working.

Is mise,

Stevie


#3

Hi Stevie,

thank you very much for the advice. I have tried to compile it removing
the extern C wrap but it is not working, it keep on displaying the same
error message.

Maybe I’m wrong, but since all the files in the directory
lib/reed-solomon are written in C instead of C++, isn’t the wrap “extern
C” necessary in my C++ component code?

Thanks again.

Alvaro