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-rw-r--r--src/lib/viterbi_detector.h498
1 files changed, 1 insertions, 497 deletions
diff --git a/src/lib/viterbi_detector.h b/src/lib/viterbi_detector.h
index 2a2fede..9ecb2a0 100644
--- a/src/lib/viterbi_detector.h
+++ b/src/lib/viterbi_detector.h
@@ -53,500 +53,4 @@
** TEST(S): Tested with real world normal burst.
*/
-#include <gnuradio/gr_complex.h>
-#include <gsm_constants.h>
-#define PATHS_NUM (1 << (CHAN_IMP_RESP_LENGTH-1))
-
-void viterbi_detector(const gr_complex * input, unsigned int samples_num, gr_complex * rhh, unsigned int start_state, const unsigned int * stop_states, unsigned int stops_num, float * output)
-{
- float increment[8];
- float path_metrics1[16];
- float path_metrics2[16];
- float * new_path_metrics;
- float * old_path_metrics;
- float * tmp;
- float trans_table[BURST_SIZE][16];
- float pm_candidate1, pm_candidate2;
- bool real_imag;
- float input_symbol_real, input_symbol_imag;
- unsigned int i, sample_nr;
-
-/*
-* Setup first path metrics, so only state pointed by start_state is possible.
-* Start_state metric is equal to zero, the rest is written with some very low value,
-* which makes them practically impossible to occur.
-*/
- for(i=0; i<PATHS_NUM; i++){
- path_metrics1[i]=(-10e30);
- }
- path_metrics1[start_state]=0;
-
-/*
-* Compute Increment - a table of values which does not change for subsequent input samples.
-* Increment is table of reference levels for computation of branch metrics:
-* branch metric = (+/-)received_sample (+/-) reference_level
-*/
- increment[0] = -rhh[1].imag() -rhh[2].real() -rhh[3].imag() +rhh[4].real();
- increment[1] = rhh[1].imag() -rhh[2].real() -rhh[3].imag() +rhh[4].real();
- increment[2] = -rhh[1].imag() +rhh[2].real() -rhh[3].imag() +rhh[4].real();
- increment[3] = rhh[1].imag() +rhh[2].real() -rhh[3].imag() +rhh[4].real();
- increment[4] = -rhh[1].imag() -rhh[2].real() +rhh[3].imag() +rhh[4].real();
- increment[5] = rhh[1].imag() -rhh[2].real() +rhh[3].imag() +rhh[4].real();
- increment[6] = -rhh[1].imag() +rhh[2].real() +rhh[3].imag() +rhh[4].real();
- increment[7] = rhh[1].imag() +rhh[2].real() +rhh[3].imag() +rhh[4].real();
-
-
-/*
-* Computation of path metrics and decisions (Add-Compare-Select).
-* It's composed of two parts: one for odd input samples (imaginary numbers)
-* and one for even samples (real numbers).
-* Each part is composed of independent (parallelisable) statements like
-* this one:
-* pm_candidate1 = old_path_metrics[0] - input_symbol_real - increment[7];
-* pm_candidate2 = old_path_metrics[8] - input_symbol_real + increment[0];
-* if(pm_candidate1 > pm_candidate2){
-* new_path_metrics[0] = pm_candidate1;
-* trans_table[sample_nr][0] = -1.0;
-* }
-* else{
-* new_path_metrics[0] = pm_candidate2;
-* trans_table[sample_nr][0] = 1.0;
-* }
-* This is very good point for optimisations (SIMD or OpenMP) as it's most time
-* consuming part of this function.
-*/
- sample_nr=0;
- old_path_metrics=path_metrics1;
- new_path_metrics=path_metrics2;
- while(sample_nr<samples_num){
- //Processing imag states
- real_imag=1;
- input_symbol_imag = input[sample_nr].imag();
-
- pm_candidate1 = old_path_metrics[0] + input_symbol_imag - increment[2];
- pm_candidate2 = old_path_metrics[8] + input_symbol_imag + increment[5];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[0] = pm_candidate1;
- trans_table[sample_nr][0] = -1.0;
- }
- else{
- new_path_metrics[0] = pm_candidate2;
- trans_table[sample_nr][0] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[0] - input_symbol_imag + increment[2];
- pm_candidate2 = old_path_metrics[8] - input_symbol_imag - increment[5];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[1] = pm_candidate1;
- trans_table[sample_nr][1] = -1.0;
- }
- else{
- new_path_metrics[1] = pm_candidate2;
- trans_table[sample_nr][1] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[1] + input_symbol_imag - increment[3];
- pm_candidate2 = old_path_metrics[9] + input_symbol_imag + increment[4];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[2] = pm_candidate1;
- trans_table[sample_nr][2] = -1.0;
- }
- else{
- new_path_metrics[2] = pm_candidate2;
- trans_table[sample_nr][2] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[1] - input_symbol_imag + increment[3];
- pm_candidate2 = old_path_metrics[9] - input_symbol_imag - increment[4];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[3] = pm_candidate1;
- trans_table[sample_nr][3] = -1.0;
- }
- else{
- new_path_metrics[3] = pm_candidate2;
- trans_table[sample_nr][3] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[2] + input_symbol_imag - increment[0];
- pm_candidate2 = old_path_metrics[10] + input_symbol_imag + increment[7];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[4] = pm_candidate1;
- trans_table[sample_nr][4] = -1.0;
- }
- else{
- new_path_metrics[4] = pm_candidate2;
- trans_table[sample_nr][4] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[2] - input_symbol_imag + increment[0];
- pm_candidate2 = old_path_metrics[10] - input_symbol_imag - increment[7];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[5] = pm_candidate1;
- trans_table[sample_nr][5] = -1.0;
- }
- else{
- new_path_metrics[5] = pm_candidate2;
- trans_table[sample_nr][5] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[3] + input_symbol_imag - increment[1];
- pm_candidate2 = old_path_metrics[11] + input_symbol_imag + increment[6];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[6] = pm_candidate1;
- trans_table[sample_nr][6] = -1.0;
- }
- else{
- new_path_metrics[6] = pm_candidate2;
- trans_table[sample_nr][6] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[3] - input_symbol_imag + increment[1];
- pm_candidate2 = old_path_metrics[11] - input_symbol_imag - increment[6];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[7] = pm_candidate1;
- trans_table[sample_nr][7] = -1.0;
- }
- else{
- new_path_metrics[7] = pm_candidate2;
- trans_table[sample_nr][7] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[4] + input_symbol_imag - increment[6];
- pm_candidate2 = old_path_metrics[12] + input_symbol_imag + increment[1];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[8] = pm_candidate1;
- trans_table[sample_nr][8] = -1.0;
- }
- else{
- new_path_metrics[8] = pm_candidate2;
- trans_table[sample_nr][8] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[4] - input_symbol_imag + increment[6];
- pm_candidate2 = old_path_metrics[12] - input_symbol_imag - increment[1];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[9] = pm_candidate1;
- trans_table[sample_nr][9] = -1.0;
- }
- else{
- new_path_metrics[9] = pm_candidate2;
- trans_table[sample_nr][9] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[5] + input_symbol_imag - increment[7];
- pm_candidate2 = old_path_metrics[13] + input_symbol_imag + increment[0];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[10] = pm_candidate1;
- trans_table[sample_nr][10] = -1.0;
- }
- else{
- new_path_metrics[10] = pm_candidate2;
- trans_table[sample_nr][10] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[5] - input_symbol_imag + increment[7];
- pm_candidate2 = old_path_metrics[13] - input_symbol_imag - increment[0];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[11] = pm_candidate1;
- trans_table[sample_nr][11] = -1.0;
- }
- else{
- new_path_metrics[11] = pm_candidate2;
- trans_table[sample_nr][11] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[6] + input_symbol_imag - increment[4];
- pm_candidate2 = old_path_metrics[14] + input_symbol_imag + increment[3];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[12] = pm_candidate1;
- trans_table[sample_nr][12] = -1.0;
- }
- else{
- new_path_metrics[12] = pm_candidate2;
- trans_table[sample_nr][12] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[6] - input_symbol_imag + increment[4];
- pm_candidate2 = old_path_metrics[14] - input_symbol_imag - increment[3];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[13] = pm_candidate1;
- trans_table[sample_nr][13] = -1.0;
- }
- else{
- new_path_metrics[13] = pm_candidate2;
- trans_table[sample_nr][13] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[7] + input_symbol_imag - increment[5];
- pm_candidate2 = old_path_metrics[15] + input_symbol_imag + increment[2];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[14] = pm_candidate1;
- trans_table[sample_nr][14] = -1.0;
- }
- else{
- new_path_metrics[14] = pm_candidate2;
- trans_table[sample_nr][14] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[7] - input_symbol_imag + increment[5];
- pm_candidate2 = old_path_metrics[15] - input_symbol_imag - increment[2];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[15] = pm_candidate1;
- trans_table[sample_nr][15] = -1.0;
- }
- else{
- new_path_metrics[15] = pm_candidate2;
- trans_table[sample_nr][15] = 1.0;
- }
- tmp=old_path_metrics;
- old_path_metrics=new_path_metrics;
- new_path_metrics=tmp;
-
- sample_nr++;
- if(sample_nr==samples_num)
- break;
-
- //Processing real states
- real_imag=0;
- input_symbol_real = input[sample_nr].real();
-
- pm_candidate1 = old_path_metrics[0] - input_symbol_real - increment[7];
- pm_candidate2 = old_path_metrics[8] - input_symbol_real + increment[0];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[0] = pm_candidate1;
- trans_table[sample_nr][0] = -1.0;
- }
- else{
- new_path_metrics[0] = pm_candidate2;
- trans_table[sample_nr][0] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[0] + input_symbol_real + increment[7];
- pm_candidate2 = old_path_metrics[8] + input_symbol_real - increment[0];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[1] = pm_candidate1;
- trans_table[sample_nr][1] = -1.0;
- }
- else{
- new_path_metrics[1] = pm_candidate2;
- trans_table[sample_nr][1] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[1] - input_symbol_real - increment[6];
- pm_candidate2 = old_path_metrics[9] - input_symbol_real + increment[1];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[2] = pm_candidate1;
- trans_table[sample_nr][2] = -1.0;
- }
- else{
- new_path_metrics[2] = pm_candidate2;
- trans_table[sample_nr][2] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[1] + input_symbol_real + increment[6];
- pm_candidate2 = old_path_metrics[9] + input_symbol_real - increment[1];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[3] = pm_candidate1;
- trans_table[sample_nr][3] = -1.0;
- }
- else{
- new_path_metrics[3] = pm_candidate2;
- trans_table[sample_nr][3] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[2] - input_symbol_real - increment[5];
- pm_candidate2 = old_path_metrics[10] - input_symbol_real + increment[2];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[4] = pm_candidate1;
- trans_table[sample_nr][4] = -1.0;
- }
- else{
- new_path_metrics[4] = pm_candidate2;
- trans_table[sample_nr][4] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[2] + input_symbol_real + increment[5];
- pm_candidate2 = old_path_metrics[10] + input_symbol_real - increment[2];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[5] = pm_candidate1;
- trans_table[sample_nr][5] = -1.0;
- }
- else{
- new_path_metrics[5] = pm_candidate2;
- trans_table[sample_nr][5] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[3] - input_symbol_real - increment[4];
- pm_candidate2 = old_path_metrics[11] - input_symbol_real + increment[3];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[6] = pm_candidate1;
- trans_table[sample_nr][6] = -1.0;
- }
- else{
- new_path_metrics[6] = pm_candidate2;
- trans_table[sample_nr][6] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[3] + input_symbol_real + increment[4];
- pm_candidate2 = old_path_metrics[11] + input_symbol_real - increment[3];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[7] = pm_candidate1;
- trans_table[sample_nr][7] = -1.0;
- }
- else{
- new_path_metrics[7] = pm_candidate2;
- trans_table[sample_nr][7] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[4] - input_symbol_real - increment[3];
- pm_candidate2 = old_path_metrics[12] - input_symbol_real + increment[4];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[8] = pm_candidate1;
- trans_table[sample_nr][8] = -1.0;
- }
- else{
- new_path_metrics[8] = pm_candidate2;
- trans_table[sample_nr][8] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[4] + input_symbol_real + increment[3];
- pm_candidate2 = old_path_metrics[12] + input_symbol_real - increment[4];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[9] = pm_candidate1;
- trans_table[sample_nr][9] = -1.0;
- }
- else{
- new_path_metrics[9] = pm_candidate2;
- trans_table[sample_nr][9] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[5] - input_symbol_real - increment[2];
- pm_candidate2 = old_path_metrics[13] - input_symbol_real + increment[5];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[10] = pm_candidate1;
- trans_table[sample_nr][10] = -1.0;
- }
- else{
- new_path_metrics[10] = pm_candidate2;
- trans_table[sample_nr][10] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[5] + input_symbol_real + increment[2];
- pm_candidate2 = old_path_metrics[13] + input_symbol_real - increment[5];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[11] = pm_candidate1;
- trans_table[sample_nr][11] = -1.0;
- }
- else{
- new_path_metrics[11] = pm_candidate2;
- trans_table[sample_nr][11] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[6] - input_symbol_real - increment[1];
- pm_candidate2 = old_path_metrics[14] - input_symbol_real + increment[6];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[12] = pm_candidate1;
- trans_table[sample_nr][12] = -1.0;
- }
- else{
- new_path_metrics[12] = pm_candidate2;
- trans_table[sample_nr][12] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[6] + input_symbol_real + increment[1];
- pm_candidate2 = old_path_metrics[14] + input_symbol_real - increment[6];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[13] = pm_candidate1;
- trans_table[sample_nr][13] = -1.0;
- }
- else{
- new_path_metrics[13] = pm_candidate2;
- trans_table[sample_nr][13] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[7] - input_symbol_real - increment[0];
- pm_candidate2 = old_path_metrics[15] - input_symbol_real + increment[7];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[14] = pm_candidate1;
- trans_table[sample_nr][14] = -1.0;
- }
- else{
- new_path_metrics[14] = pm_candidate2;
- trans_table[sample_nr][14] = 1.0;
- }
-
- pm_candidate1 = old_path_metrics[7] + input_symbol_real + increment[0];
- pm_candidate2 = old_path_metrics[15] + input_symbol_real - increment[7];
- if(pm_candidate1 > pm_candidate2){
- new_path_metrics[15] = pm_candidate1;
- trans_table[sample_nr][15] = -1.0;
- }
- else{
- new_path_metrics[15] = pm_candidate2;
- trans_table[sample_nr][15] = 1.0;
- }
- tmp=old_path_metrics;
- old_path_metrics=new_path_metrics;
- new_path_metrics=tmp;
-
- sample_nr++;
- }
-
-/*
-* Find the best from the stop states by comparing their path metrics.
-* Not every stop state is always possible, so we are searching in
-* a subset of them.
-*/
- unsigned int best_stop_state;
- float stop_state_metric, max_stop_state_metric;
- best_stop_state = stop_states[0];
- max_stop_state_metric = old_path_metrics[best_stop_state];
- for(i=1; i< stops_num; i++){
- stop_state_metric = old_path_metrics[stop_states[i]];
- if(stop_state_metric > max_stop_state_metric){
- max_stop_state_metric = stop_state_metric;
- best_stop_state = stop_states[i];
- }
- }
-
-/*
-* This table was generated with hope that it gives a litle speedup during
-* traceback stage.
-* Received bit is related to the number of state in the trellis.
-* I've numbered states so their parity (number of ones) is related
-* to a received bit.
-*/
- static const unsigned int parity_table[PATHS_NUM] = { 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, };
-
-/*
-* Table of previous states in the trellis diagram.
-* For GMSK modulation every state has two previous states.
-* Example:
-* previous_state_nr1 = prev_table[current_state_nr][0]
-* previous_state_nr2 = prev_table[current_state_nr][1]
-*/
- static const unsigned int prev_table[PATHS_NUM][2] = { {0,8}, {0,8}, {1,9}, {1,9}, {2,10}, {2,10}, {3,11}, {3,11}, {4,12}, {4,12}, {5,13}, {5,13}, {6,14}, {6,14}, {7,15}, {7,15}, };
-
-/*
-* Traceback and differential decoding of received sequence.
-* Decisions stored in trans_table are used to restore best path in the trellis.
-*/
- sample_nr=samples_num;
- unsigned int state_nr=best_stop_state;
- unsigned int decision;
- bool out_bit=0;
-
- while(sample_nr>0){
- sample_nr--;
- decision = (trans_table[sample_nr][state_nr]>0);
-
- if(decision != out_bit)
- output[sample_nr]=-trans_table[sample_nr][state_nr];
- else
- output[sample_nr]=trans_table[sample_nr][state_nr];
-
- out_bit = out_bit ^ real_imag ^ parity_table[state_nr];
- state_nr = prev_table[state_nr][decision];
- real_imag = !real_imag;
- }
-}
+void viterbi_detector(const gr_complex * input, unsigned int samples_num, gr_complex * rhh, unsigned int start_state, const unsigned int * stop_states, unsigned int stops_num, float * output);
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