Hi people,
In an effort to write a c++ qpsk mapper/demapper i found that the quite
useful block "gr_unpack_k_bits", but I couldn't find the "inverse", so I
wrote it.
I have tested it using the following flow- graph:
file_source -> bit- packer -> constellation- mapper -> constellation-
demapper -> bit- unpacker -> file_sink
where
file_source contains random bits generated in matlab.
packer packs two consecutive bits together
constellation- mapper is a qpsk- mapper
constellation- demapper is the inverse
unpacker is a gr_unpack_k_bits_bb
I have tested it for "gr_pack_k_bits_bb(2)" and "gr_unpack_k_bits_bb(2)".
Hope this can be incorporated into the tree.
Best regards
//Mattias Kjellsson
#include "gr_pack_k_bits_bb.h"
#include <gr_io_signature.h>
#include <stdexcept>
#include <iostream>
gr_pack_k_bits_bb_sptr gr_make_pack_k_bits_bb(unsigned k){
return gr_pack_k_bits_bb_sptr (new gr_pack_k_bits_bb(k));
}
gr_pack_k_bits_bb::gr_pack_k_bits_bb(unsigned k)
: gr_sync_decimator("pack_k_bits_bb",
gr_make_io_signature (1, 1, sizeof (unsigned char)),
gr_make_io_signature (1, 1, sizeof (unsigned char)),
k),
d_k(k){
if (d_k == 0)
throw std::out_of_range ("decimation must be > 0");
}
gr_pack_k_bits_bb::~gr_pack_k_bits_bb(){
}
int gr_pack_k_bits_bb::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];
int n = 0;
for(unsigned int i=0;i<noutput_items * d_k ;i=i+d_k){
/* Working for two...
char t1 = in[i];
char t2 = in[i+1];
out[n] = ( (t1<<1) + t2 ) & 0x3;
//printf("i: %d\t t1: 0x%0x\t t2: 0x%0x\t out[%d] = 0x%0x\n",
// i, t1, t2, n, out[n]);
n++;
*/
/*Trying for more */
int c = 0;
for(int j=(d_k-1);j>=0;j--){
char t = in[i+c++];
out[n] = out[n] + (t<<j);
}
out[n] = out[n] & (d_k+1);
n++;
}
//assert(n == noutput_items);
return noutput_items;
}
#ifndef INCLUDED_GR_PACK_K_BITS_BB_H
#define INCLUDED_GR_PACK_K_BITS_BB_H
#include <gr_sync_decimator.h>
class gr_pack_k_bits_bb;
typedef boost::shared_ptr<gr_pack_k_bits_bb> gr_pack_k_bits_bb_sptr;
gr_pack_k_bits_bb_sptr gr_make_pack_k_bits_bb(unsigned k);
class gr_pack_k_bits_bb : public gr_sync_decimator{
private:
friend gr_pack_k_bits_bb_sptr gr_make_pack_k_bits_bb(unsigned k);
gr_pack_k_bits_bb(unsigned k);
unsigned int d_k;
public:
~gr_pack_k_bits_bb ();
int work(int noutput_items,
gr_vector_const_void_star &input_items,
gr_vector_void_star &output_items);
};
#endif
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