From 8e1bdafc51d59d405d55e9f76ae1e76877de6766 Mon Sep 17 00:00:00 2001
From: Nick Foster <nick@ettus.com>
Date: Sun, 4 Aug 2013 22:14:08 -0700
Subject: [PATCH] Re-tab air_modes_preamble.cc

---
 lib/air_modes_preamble.cc | 282 +++++++++++++++++++-------------------
 1 file changed, 141 insertions(+), 141 deletions(-)

diff --git a/lib/air_modes_preamble.cc b/lib/air_modes_preamble.cc
index 7498d8a..13ca7c6 100644
--- a/lib/air_modes_preamble.cc
+++ b/lib/air_modes_preamble.cc
@@ -34,183 +34,183 @@
 
 air_modes_preamble_sptr air_make_modes_preamble(int channel_rate, float threshold_db)
 {
-	return air_modes_preamble_sptr (new air_modes_preamble(channel_rate, threshold_db));
+    return air_modes_preamble_sptr (new air_modes_preamble(channel_rate, threshold_db));
 }
 
 air_modes_preamble::air_modes_preamble(int channel_rate, float threshold_db) :
         gr::block ("modes_preamble",
-	       gr::io_signature::make2 (2, 2, sizeof(float), sizeof(float)), //stream 0 is received data, stream 1 is moving average for reference
-	       gr::io_signature::make (1, 1, sizeof(float))) //the output packets
+           gr::io_signature::make2 (2, 2, sizeof(float), sizeof(float)), //stream 0 is received data, stream 1 is moving average for reference
+           gr::io_signature::make (1, 1, sizeof(float))) //the output packets
 {
-	d_chip_rate = 2000000; //2Mchips per second
-	d_samples_per_chip = channel_rate / d_chip_rate; //must be integer number of samples per chip to work
-	d_samples_per_symbol = d_samples_per_chip * 2;
-	d_check_width = 120 * d_samples_per_symbol; //only search to this far from the end of the stream buffer
-	d_threshold_db = threshold_db;
-	d_threshold = powf(10., threshold_db/20.); //the level that the sample must be above the moving average in order to qualify as a pulse
-	d_secs_per_sample = 1.0 / channel_rate;
-	set_output_multiple(1+d_check_width*2);
-	
-	std::stringstream str;
-	str << name() << unique_id();
-	d_me = pmt::string_to_symbol(str.str());
-	d_key = pmt::string_to_symbol("preamble_found");
-	set_history(d_samples_per_symbol);
+    d_chip_rate = 2000000; //2Mchips per second
+    d_samples_per_chip = channel_rate / d_chip_rate; //must be integer number of samples per chip to work
+    d_samples_per_symbol = d_samples_per_chip * 2;
+    d_check_width = 120 * d_samples_per_symbol; //only search to this far from the end of the stream buffer
+    d_threshold_db = threshold_db;
+    d_threshold = powf(10., threshold_db/20.); //the level that the sample must be above the moving average in order to qualify as a pulse
+    d_secs_per_sample = 1.0 / channel_rate;
+    set_output_multiple(1+d_check_width*2);
+    
+    std::stringstream str;
+    str << name() << unique_id();
+    d_me = pmt::string_to_symbol(str.str());
+    d_key = pmt::string_to_symbol("preamble_found");
+    set_history(d_samples_per_symbol);
 }
 
 static void integrate_and_dump(float *out, const float *in, int chips, int samps_per_chip) {
-	for(int i=0; i<chips; i++) {
-		float acc = 0;
-		for(int j=0; j<samps_per_chip; j++) {
-			acc += in[i*samps_per_chip+j];
-		}
-		out[i] = acc;
-	}
+    for(int i=0; i<chips; i++) {
+        float acc = 0;
+        for(int j=0; j<samps_per_chip; j++) {
+            acc += in[i*samps_per_chip+j];
+        }
+        out[i] = acc;
+    }
 }
 
 //the preamble pattern in bits
 //fixme goes in .h
 static const bool preamble_bits[] = {1, 0, 1, 0, 0, 0, 0, 1, 0, 1};
 static double correlate_preamble(const float *in, int samples_per_chip) {
-	double corr = 0.0;
-	for(int i=0; i<10; i++) {
-		for(int j=0; j<samples_per_chip;j++)
-			if(preamble_bits[i]) corr += in[i*samples_per_chip+j];
-	}
-	return corr;
+    double corr = 0.0;
+    for(int i=0; i<10; i++) {
+        for(int j=0; j<samples_per_chip;j++)
+            if(preamble_bits[i]) corr += in[i*samples_per_chip+j];
+    }
+    return corr;
 }
 
 //todo: make it return a pair of some kind, otherwise you can lose precision
 static double tag_to_timestamp(gr::tag_t tstamp, uint64_t abs_sample_cnt, double secs_per_sample) {
-	uint64_t ts_sample, last_whole_stamp;
-	double last_frac_stamp;
+    uint64_t ts_sample, last_whole_stamp;
+    double last_frac_stamp;
 
-	if(tstamp.key == NULL || pmt::symbol_to_string(tstamp.key) != "rx_time") return 0;
+    if(tstamp.key == NULL || pmt::symbol_to_string(tstamp.key) != "rx_time") return 0;
 
-	last_whole_stamp = pmt::to_uint64(pmt::tuple_ref(tstamp.value, 0));
-	last_frac_stamp = pmt::to_double(pmt::tuple_ref(tstamp.value, 1));
-	ts_sample = tstamp.offset;
-	
-	double tstime = double(abs_sample_cnt * secs_per_sample) + last_whole_stamp + last_frac_stamp;
-	if(0) std::cout << "HEY WE GOT A STAMP AT " << tstime << " TICKS AT SAMPLE " << ts_sample << " ABS SAMPLE CNT IS " << abs_sample_cnt << std::endl;
-	return tstime;
+    last_whole_stamp = pmt::to_uint64(pmt::tuple_ref(tstamp.value, 0));
+    last_frac_stamp = pmt::to_double(pmt::tuple_ref(tstamp.value, 1));
+    ts_sample = tstamp.offset;
+    
+    double tstime = double(abs_sample_cnt * secs_per_sample) + last_whole_stamp + last_frac_stamp;
+    if(0) std::cout << "HEY WE GOT A STAMP AT " << tstime << " TICKS AT SAMPLE " << ts_sample << " ABS SAMPLE CNT IS " << abs_sample_cnt << std::endl;
+    return tstime;
 }
 
 int air_modes_preamble::general_work(int noutput_items,
-						  gr_vector_int &ninput_items,
+                          gr_vector_int &ninput_items,
                           gr_vector_const_void_star &input_items,
-		                  gr_vector_void_star &output_items)
+                          gr_vector_void_star &output_items)
 {
-	const float *in = (const float *) input_items[0];
-	const float *inavg = (const float *) input_items[1];
+    const float *in = (const float *) input_items[0];
+    const float *inavg = (const float *) input_items[1];
 
-	int mininputs = std::min(ninput_items[0], ninput_items[1]); //they should be matched but let's be safe
-	//round number of input samples down to nearest d_samples_per_chip
-	//we also subtract off d_samples_per_chip to allow the bit center finder some leeway
-	const int ninputs = std::max(mininputs - (mininputs % d_samples_per_chip) - d_samples_per_chip, 0);
-	if (ninputs <= 0) { consume_each(0); return 0; }
-	
-	float *out = (float *) output_items[0];
+    int mininputs = std::min(ninput_items[0], ninput_items[1]); //they should be matched but let's be safe
+    //round number of input samples down to nearest d_samples_per_chip
+    //we also subtract off d_samples_per_chip to allow the bit center finder some leeway
+    const int ninputs = std::max(mininputs - (mininputs % d_samples_per_chip) - d_samples_per_chip, 0);
+    if (ninputs <= 0) { consume_each(0); return 0; }
+    
+    float *out = (float *) output_items[0];
 
-	if(0) std::cout << "Preamble called with " << ninputs << " samples" << std::endl;
+    if(0) std::cout << "Preamble called with " << ninputs << " samples" << std::endl;
 
-	//fixme move into .h
-	const int pulse_offsets[4] = {    0,
-	                              int(2 * d_samples_per_chip),
-	                              int(7 * d_samples_per_chip),
-	                              int(9 * d_samples_per_chip)
-	                             };
+    //fixme move into .h
+    const int pulse_offsets[4] = {    0,
+                                  int(2 * d_samples_per_chip),
+                                  int(7 * d_samples_per_chip),
+                                  int(9 * d_samples_per_chip)
+                                 };
 
-	uint64_t abs_sample_cnt = nitems_read(0);
-	std::vector<gr::tag_t> tstamp_tags;
-	get_tags_in_range(tstamp_tags, 0, abs_sample_cnt, abs_sample_cnt + ninputs, pmt::string_to_symbol("rx_time"));
-	//tags.back() is the most recent timestamp, then.
-	if(tstamp_tags.size() > 0) {
-		d_timestamp = tstamp_tags.back();
-	}
-	
-	for(int i=0; i < ninputs; i++) {
-		float pulse_threshold = inavg[i] * d_threshold;
-		if(in[i] > pulse_threshold) { //hey we got a candidate
-			if(in[i+1] > in[i]) continue; //wait for the peak
-			//check to see the rest of the pulses are there
-			if( in[i+pulse_offsets[1]] < pulse_threshold ) continue;
-			if( in[i+pulse_offsets[2]] < pulse_threshold ) continue;
-			if( in[i+pulse_offsets[3]] < pulse_threshold ) continue;
+    uint64_t abs_sample_cnt = nitems_read(0);
+    std::vector<gr::tag_t> tstamp_tags;
+    get_tags_in_range(tstamp_tags, 0, abs_sample_cnt, abs_sample_cnt + ninputs, pmt::string_to_symbol("rx_time"));
+    //tags.back() is the most recent timestamp, then.
+    if(tstamp_tags.size() > 0) {
+        d_timestamp = tstamp_tags.back();
+    }
+    
+    for(int i=0; i < ninputs; i++) {
+        float pulse_threshold = inavg[i] * d_threshold;
+        if(in[i] > pulse_threshold) { //hey we got a candidate
+            if(in[i+1] > in[i]) continue; //wait for the peak
+            //check to see the rest of the pulses are there
+            if( in[i+pulse_offsets[1]] < pulse_threshold ) continue;
+            if( in[i+pulse_offsets[2]] < pulse_threshold ) continue;
+            if( in[i+pulse_offsets[3]] < pulse_threshold ) continue;
 
-			//get a more accurate bit center by finding the correlation peak across all four preamble bits
-			bool late, early;
-			int how_late = 0;
-			do {
-				double now_corr = correlate_preamble(in+i, d_samples_per_chip);
-				double late_corr = correlate_preamble(in+i+1, d_samples_per_chip);
-				double early_corr = correlate_preamble(in+i-1, d_samples_per_chip);
-				late = (late_corr > now_corr);
-				//early = (early_corr > now_corr);
-				if(late) { i++; how_late++; }
-				//if(early && i>0) { std::cout << "EARLY " << i << std::endl; i--; }
-			} while(late and how_late < d_samples_per_chip);// xor early);
+            //get a more accurate bit center by finding the correlation peak across all four preamble bits
+            bool late, early;
+            int how_late = 0;
+            do {
+                double now_corr = correlate_preamble(in+i, d_samples_per_chip);
+                double late_corr = correlate_preamble(in+i+1, d_samples_per_chip);
+                double early_corr = correlate_preamble(in+i-1, d_samples_per_chip);
+                late = (late_corr > now_corr);
+                //early = (early_corr > now_corr);
+                if(late) { i++; how_late++; }
+                //if(early && i>0) { std::cout << "EARLY " << i << std::endl; i--; }
+            } while(late and how_late < d_samples_per_chip);// xor early);
 
-			if(0) std::cout << "We were " << how_late << " samples late" << std::endl;
+            if(0) std::cout << "We were " << how_late << " samples late" << std::endl;
 
-			//now check to see that the non-peak symbols in the preamble
-			//are below the peaks by threshold dB
-			float avgpeak = ( in[i+pulse_offsets[0]]
-			                + in[i+pulse_offsets[1]]
-			                + in[i+pulse_offsets[2]]
-			                + in[i+pulse_offsets[3]]) / 4.0;
+            //now check to see that the non-peak symbols in the preamble
+            //are below the peaks by threshold dB
+            float avgpeak = ( in[i+pulse_offsets[0]]
+                            + in[i+pulse_offsets[1]]
+                            + in[i+pulse_offsets[2]]
+                            + in[i+pulse_offsets[3]]) / 4.0;
 
-			float space_threshold = inavg[i] + (avgpeak - inavg[i])/d_threshold;
-			bool valid_preamble = true; //f'in c++
-			for( int j=1.5*d_samples_per_symbol; j<=3*d_samples_per_symbol; j++)
-				if(in[i+j] > space_threshold) valid_preamble = false;
-			for( int j=5*d_samples_per_symbol; j<=7.5*d_samples_per_symbol; j++)
-				if(in[i+j] > space_threshold) valid_preamble = false;
-			if(!valid_preamble) continue;
+            float space_threshold = inavg[i] + (avgpeak - inavg[i])/d_threshold;
+            bool valid_preamble = true; //f'in c++
+            for( int j=1.5*d_samples_per_symbol; j<=3*d_samples_per_symbol; j++)
+                if(in[i+j] > space_threshold) valid_preamble = false;
+            for( int j=5*d_samples_per_symbol; j<=7.5*d_samples_per_symbol; j++)
+                if(in[i+j] > space_threshold) valid_preamble = false;
+            if(!valid_preamble) continue;
 
-			//be sure we've got enough room in the input buffer to copy out a whole packet
-			if(ninputs-i < 240*d_samples_per_chip) {
-				consume_each(std::max(i-1,0));
-				if(0) std::cout << "Preamble consumed " << std::max(i-1,0) << ", returned 0 (no room)" << std::endl;
-				return 0;
-			}
+            //be sure we've got enough room in the input buffer to copy out a whole packet
+            if(ninputs-i < 240*d_samples_per_chip) {
+                consume_each(std::max(i-1,0));
+                if(0) std::cout << "Preamble consumed " << std::max(i-1,0) << ", returned 0 (no room)" << std::endl;
+                return 0;
+            }
 
-			//all right i'm prepared to call this a preamble			
-			//let's integrate and dump the output
-			//FIXME: disable and use center sample
-			bool life_sucks = true;
-			if(life_sucks) {
-				for(int j=0; j<240; j++) {
-					out[j] = in[i+j*d_samples_per_chip];
-				}
-			} else {
-				i -= d_samples_per_chip-1;
-				integrate_and_dump(out, &in[i], 240, d_samples_per_chip);
-			}
+            //all right i'm prepared to call this a preamble            
+            //let's integrate and dump the output
+            //FIXME: disable and use center sample
+            bool life_sucks = true;
+            if(life_sucks) {
+                for(int j=0; j<240; j++) {
+                    out[j] = in[i+j*d_samples_per_chip];
+                }
+            } else {
+                i -= d_samples_per_chip-1;
+                integrate_and_dump(out, &in[i], 240, d_samples_per_chip);
+            }
 
-			//get the timestamp of the preamble
-			double tstamp = tag_to_timestamp(d_timestamp, abs_sample_cnt + i, d_secs_per_sample);
+            //get the timestamp of the preamble
+            double tstamp = tag_to_timestamp(d_timestamp, abs_sample_cnt + i, d_secs_per_sample);
 
-			//now tag the preamble
-			add_item_tag(0, //stream ID
-					 nitems_written(0), //sample
-					 d_key,      //frame_info
-			         pmt::from_double(tstamp),
-			         d_me        //block src id
-			        );
-					 
-			//std::cout << "PREAMBLE" << std::endl;
-			
-			//produce only one output per work call -- TODO this should probably change
-			if(0) std::cout << "Preamble consumed " << i+240*d_samples_per_chip << "with i=" << i << ", returned 240" << std::endl;
+            //now tag the preamble
+            add_item_tag(0, //stream ID
+                     nitems_written(0), //sample
+                     d_key,      //frame_info
+                     pmt::from_double(tstamp),
+                     d_me        //block src id
+                    );
+                     
+            //std::cout << "PREAMBLE" << std::endl;
+            
+            //produce only one output per work call -- TODO this should probably change
+            if(0) std::cout << "Preamble consumed " << i+240*d_samples_per_chip << "with i=" << i << ", returned 240" << std::endl;
 
-			consume_each(i+240*d_samples_per_chip);
-			return 240;
-		}
-	}
-	
-	//didn't get anything this time
-	if(0) std::cout << "Preamble consumed " << ninputs << ", returned 0" << std::endl;
-	consume_each(ninputs);
-	return 0;
+            consume_each(i+240*d_samples_per_chip);
+            return 240;
+        }
+    }
+    
+    //didn't get anything this time
+    if(0) std::cout << "Preamble consumed " << ninputs << ", returned 0" << std::endl;
+    consume_each(ninputs);
+    return 0;
 }