Merge pull request #9 from argilo/eof-eot

Correctly handle EoF, and transmit EoT

.gitignore

@@ -2,3 +2,4 @@
 /SP5WWP/grc/symbol_recovery.py
 /SP5WWP/m17-coder/m17-coder-sym
 /SP5WWP/m17-decoder/m17-decoder-sym
+/SP5WWP/m17-packet/m17-packet-encode

SP5WWP/inc/m17.h

@@ -12,9 +12,14 @@ extern "C" {
 #define SYM_PER_FRA         192         //symbols per whole 40 ms frame
 #define RRC_DEV             7168.0f     //.rrc file deviation for +1.0 symbol
 
+#define XCORR_THRESH		0.90		//arbitrary threshold between 0 and 1
+#define SW_MEAN				-0.75		//mean(str_sync)=mean(pkt_sync)
+#define SW_STD				8.21583836f	//std(str_sync)*sqrt(length(str_sync)-1)
+
 //syncword patterns (RX) TODO:Compute those at runtime from the consts below
-const int8_t str_sync[8]={-3, -3, -3, -3, +3, +3, -3, +3};
 const int8_t lsf_sync[8]={+3, +3, +3, +3, -3, -3, +3, -3};
+const int8_t str_sync[8]={-3, -3, -3, -3, +3, +3, -3, +3};
+const int8_t pkt_sync[8]={+3, -3, +3, +3, -3, -3, -3, -3};
 
 //symbol levels (RX)
 const float symbs[4]={-3.0, -1.0, +1.0, +3.0};

SP5WWP/m17-coder/m17-coder-sym.c

@@ -16,17 +16,18 @@ struct LSF
 	uint8_t type[2];
 	uint8_t meta[112/8];
 	uint8_t crc[2];
-} lsf;
+} lsf, next_lsf;
 
 uint8_t lich[6];                    //48 bits packed raw, unencoded LICH
 uint8_t lich_encoded[12];           //96 bits packed, encoded LICH
 uint8_t enc_bits[SYM_PER_PLD*2];    //type-2 bits, unpacked
 uint8_t rf_bits[SYM_PER_PLD*2];     //type-4 bits, unpacked
 
-uint8_t data[16];                   //raw payload, packed bits
+uint8_t data[16], next_data[16];    //raw payload, packed bits
 uint16_t fn=0;                      //16-bit Frame Number (for the stream mode)
-uint8_t lich_cnt=0;                 //0..5 LICH counter, derived from the Frame Number
+uint8_t lich_cnt=0;                 //0..5 LICH counter
 uint8_t got_lsf=0;                  //have we filled the LSF struct yet?
+uint8_t finished=0;
 
 void send_Preamble(const uint8_t type)
 {
@@ -76,6 +77,15 @@ void send_data(uint8_t* in)
 	}
 }
 
+void send_EoT()
+{
+    float symb=+3.0;
+    for(uint16_t i=0; i<192; i++) //40ms * 4800 = 192
+    {
+        write(STDOUT_FILENO, (uint8_t*)&symb,  sizeof(float));
+    }
+}
+
 //out - unpacked bits
 //in - packed raw bits
 //fn - frame number
@@ -249,23 +259,35 @@ int main(void)
     //printf("%d -> %d -> %d\n", 1, intrl_seq[1], intrl_seq[intrl_seq[1]]); //interleaver bijective reciprocality test, f(f(x))=x
     //return 0;
 
-    while(1)
+    if(fread(&(next_lsf.dst), 6, 1, stdin)<1) finished=1;
+    if(fread(&(next_lsf.src), 6, 1, stdin)<1) finished=1;
+    if(fread(&(next_lsf.type), 2, 1, stdin)<1) finished=1;
+    if(fread(&(next_lsf.meta), 14, 1, stdin)<1) finished=1;
+    if(fread(next_data, 16, 1, stdin)<1) finished=1;
+
+    while(!finished)
     {
+        lsf = next_lsf;
+
+        //calculate LSF CRC
+        uint16_t ccrc=LSF_CRC(&lsf);
+        lsf.crc[0]=ccrc>>8;
+        lsf.crc[1]=ccrc&0xFF;
+
+        memcpy(data, next_data, sizeof(data));
+
+        //we could discard the data we already have
+        if(fread(&(next_lsf.dst), 6, 1, stdin)<1) finished=1;
+        if(fread(&(next_lsf.src), 6, 1, stdin)<1) finished=1;
+        if(fread(&(next_lsf.type), 2, 1, stdin)<1) finished=1;
+        if(fread(&(next_lsf.meta), 14, 1, stdin)<1) finished=1;
+        if(fread(next_data, 16, 1, stdin)<1) finished=1;
+
         if(got_lsf) //stream frames
         {
-            //we could discard the data we already have
-            while(fread(&(lsf.dst), 1, 6, stdin)<1);
-            while(fread(&(lsf.src), 1, 6, stdin)<1);
-            while(fread(&(lsf.type), 1, 2, stdin)<1);
-            while(fread(&(lsf.meta), 1, 14, stdin)<1);
-            while(fread(data, 1, 16, stdin)<1);
-
             //send stream frame syncword
             send_Syncword(SYNC_STR);
 
-            //derive the LICH_CNT from the Frame Number
-            lich_cnt=fn%6;
-
             //extract LICH from the whole LSF
             switch(lich_cnt)
             {
@@ -352,7 +374,7 @@ int main(void)
             }
 
             //encode the rest of the frame
-            conv_Encode_Frame(&enc_bits[96], data, fn);
+            conv_Encode_Frame(&enc_bits[96], data, finished ? (fn | 0x8000) : fn);
 
             //reorder bits
             for(uint16_t i=0; i<SYM_PER_PLD*2; i++)
@@ -384,7 +406,10 @@ int main(void)
             printf("\n");*/
 
             //increment the Frame Number
-            fn++;
+            fn = (fn + 1) % 0x8000;
+
+            //increment the LICH counter
+            lich_cnt = (lich_cnt + 1) % 6;
 
             //debug-only
 			#ifdef FN60_DEBUG
@@ -394,17 +419,6 @@ int main(void)
         }
         else //LSF
         {
-            while(fread(&(lsf.dst), 1, 6, stdin)<1);
-            while(fread(&(lsf.src), 1, 6, stdin)<1);
-            while(fread(&(lsf.type), 1, 2, stdin)<1);
-            while(fread(&(lsf.meta), 1, 14, stdin)<1);
-            while(fread(data, 1, 16, stdin)<1);
-
-            //calculate LSF CRC
-            uint16_t ccrc=LSF_CRC(&lsf);
-            lsf.crc[0]=ccrc>>8;
-            lsf.crc[1]=ccrc&0xFF;
-
             got_lsf=1;
 
             //encode LSF data
@@ -457,6 +471,9 @@ int main(void)
                 printf("%02X", lsf.crc[i]);
 			printf("\n");*/
 		}
+
+        if (finished)
+            send_EoT();
 	}
 
 	return 0;

SP5WWP/m17-decoder/Makefile

@@ -1,5 +1,5 @@
 m17-decoder-sym: m17-decoder-sym.c golay.c viterbi.c crc.c
-	gcc -O2 -lm m17-decoder-sym.c golay.c viterbi.c crc.c -o m17-decoder-sym
+	gcc -Wall -O2 m17-decoder-sym.c golay.c viterbi.c crc.c -o m17-decoder-sym -lm
 
 clean:
 	rm m17-decoder-sym

SP5WWP/m17-decoder/m17-decoder-sym.c

@@ -1,8 +1,8 @@
 #include <stdio.h>
 #include <stdlib.h>
-#include <unistd.h>
 #include <stdint.h>
 #include <string.h>
+#include <math.h>
 
 #include "../inc/m17.h"
 #include "golay.h"
@@ -14,7 +14,7 @@
 
 float sample;                       //last raw sample from the stdin
 float last[8];                      //look-back buffer for finding syncwords
-float xcorr;                        //cross correlation for finding syncwords
+float xcorr, meanx, normx;          //cross correlation related variables for finding syncwords
 float pld[SYM_PER_PLD];             //raw frame symbols
 uint16_t soft_bit[2*SYM_PER_PLD];   //raw frame soft bits
 uint16_t d_soft_bit[2*SYM_PER_PLD]; //deinterleaved soft bits
@@ -69,7 +69,7 @@ void decode_callsign(uint8_t *outp, const uint8_t *inp)
 	{
         if(encoded==0xFFFFFFFFFFFF) //broadcast
         {
-            sprintf(outp, "#BCAST");
+            sprintf((char*)outp, "#BCAST");
         }
         else
         {
@@ -87,6 +87,7 @@ void decode_callsign(uint8_t *outp, const uint8_t *inp)
 		encoded/=40;
 		i++;
 	}
+	outp[i]=0;
 }
 
 int main(void)
@@ -94,7 +95,7 @@ int main(void)
     while(1)
     {
         //wait for another symbol
-        while(fread((uint8_t*)&sample, 1, 4, stdin)<1);
+        if(fread((uint8_t*)&sample, 4, 1, stdin)<1) break;
 
         if(!syncd)
         {
@@ -107,22 +108,30 @@ int main(void)
             last[7]=sample;
 
             //calculate cross-correlation
-            xcorr=0;
+            meanx=0.0f;
+            for(uint8_t i=0; i<8; i++)
+                meanx+=last[i];
+            meanx=meanx/8.0f;
+
+            xcorr=0.0f;
+            normx=0.0f;
             for(uint8_t i=0; i<8; i++)
             {
-                xcorr+=last[i]*str_sync[i];
+                xcorr+=(last[i]-meanx)*(str_sync[i]-SW_MEAN);
+                normx+=(last[i]-meanx)*(last[i]-meanx);
             }
 
+            xcorr=xcorr/(sqrtf(normx)*SW_STD);
+
             //printf("%f\n", xcorr);
 
-
-            if(xcorr>62.0) //Frame syncword detected
+            if(xcorr>XCORR_THRESH) //Frame syncword detected
             {
                 syncd=1;
                 pushed=0;
                 fl=0;
             }
-            else if(xcorr<-62) //LSF syncword
+            else if(xcorr<-XCORR_THRESH) //LSF syncword
             {
                 syncd=1;
                 pushed=0;

SP5WWP/m17-decoder/m17-decoder.c

@@ -21,7 +21,7 @@ int main(void)
     while(1)
     {
         //wait for another baseband sample
-        while(fread((uint8_t*)&sample, 1, 2, stdin)<1);
+        if(fread((uint8_t*)&sample, 2, 1, stdin)<1) break;
 
         //push the root-nyquist filter's buffer
         for(uint8_t i=0; i<FLT_LEN-1; i++)

SP5WWP/m17-packet/m17-packet-encode.c

@@ -393,7 +393,11 @@ int main(int argc, char* argv[])
 
     //obtain data and append with CRC
     memset(full_packet_data, 0, 32*25);
-    while(fread(full_packet_data, 1, num_bytes, stdin)<1);
+    if(fread(full_packet_data, num_bytes, 1, stdin)<1)
+    {
+        fprintf(stderr, "Packet data too short. Exiting...\n");
+        return -1;
+    }
     uint16_t packet_crc=CRC_M17(full_packet_data, num_bytes);
     full_packet_data[num_bytes]  =packet_crc>>8;
     full_packet_data[num_bytes+1]=packet_crc&0xFF;