Add option -m to decode to metric

This enables the natural unit for 96% of the world's population.

Author: Thomas Habets

atest.c

@@ -758,7 +758,7 @@ void dlq_rec_frame (int chan, int subchan, int slice, packet_t pp, alevel_t alev
 
 	  decode_aprs_t A;
 
-	  decode_aprs (&A, pp, 0);
+	  decode_aprs (&A, pp, 0, 0);
 
 	  // Temp experiment to see how different systems set the RR bits in the source and destination.
 	  // log_rr_bits (&A, pp);

decode_aprs.c

@@ -150,7 +150,7 @@ static void process_comment (decode_aprs_t *A, char *pstart, int clen);
  *
  *------------------------------------------------------------------*/
 
-void decode_aprs (decode_aprs_t *A, packet_t pp, int quiet)
+void decode_aprs (decode_aprs_t *A, packet_t pp, int quiet, int metric)
 {
 
 	char dest[AX25_MAX_ADDR_LEN];
@@ -163,6 +163,7 @@ void decode_aprs (decode_aprs_t *A, packet_t pp, int quiet)
 	memset (A, 0, sizeof (*A));
 
 	A->g_quiet = quiet;
+	A->g_metric = metric;
 
 	snprintf (A->g_msg_type, sizeof(A->g_msg_type), "Unknown APRS Data Type Indicator \"%c\"", *pinfo);
 
@@ -543,7 +544,11 @@ void decode_aprs_print (decode_aprs_t *A) {
 	  char spd[20];
 
 	  if (strlen(stemp) > 0) strlcat (stemp, ", ", sizeof(stemp));
-	  snprintf (spd, sizeof(spd), "%.0f MPH", A->g_speed_mph);
+	  if (A->g_metric) {
+	    snprintf (spd, sizeof(spd), "%.0f km/h", DW_MILES_TO_KM(A->g_speed_mph));
+	  } else {
+	    snprintf (spd, sizeof(spd), "%.0f MPH", A->g_speed_mph);
+	  }
 	  strlcat (stemp, spd, sizeof(stemp));
 	};
 
@@ -559,7 +564,11 @@ void decode_aprs_print (decode_aprs_t *A) {
 	  char alt[20];
 
 	  if (strlen(stemp) > 0) strlcat (stemp, ", ", sizeof(stemp));
-	  snprintf (alt, sizeof(alt), "alt %.0f ft", A->g_altitude_ft);
+	  if (A->g_metric) {
+	    snprintf (alt, sizeof(alt), "alt %.0f m", DW_FEET_TO_METERS(A->g_altitude_ft));
+	  } else {
+	    snprintf (alt, sizeof(alt), "alt %.0f ft", A->g_altitude_ft);
+	  }
 	  strlcat (stemp, alt, sizeof(stemp));
 	};
 
@@ -4719,6 +4728,7 @@ int main (int argc, char *argv[])
 	int num_bytes;
 	char *p;	
 	packet_t pp;
+	int metric = 0;
 
 #if __WIN32__
 
@@ -4879,7 +4889,7 @@ int main (int argc, char *argv[])
 	        ax25_safe_print ((char *)pinfo, info_len, 1);	// Display non-ASCII to hexadecimal.
 	        dw_printf ("\n");
 
-	        decode_aprs (&A, pp, 0);			// Extract information into structure.
+	        decode_aprs (&A, pp, 0, metric);		// Extract information into structure.
 
 	        decode_aprs_print (&A);			// Now print it in human readable format.
 
@@ -4900,9 +4910,9 @@ int main (int argc, char *argv[])
 	      if (pp != NULL) {
 	        decode_aprs_t A;
 
-	        decode_aprs (&A, pp, 0);	// Extract information into structure.
+	        decode_aprs (&A, pp, 0, metric);	// Extract information into structure.
 
-	        decode_aprs_print (&A);		// Now print it in human readable format.
+	        decode_aprs_print (&A);			// Now print it in human readable format.
 
 	        // This seems to be redundant because we used strict option
 	        // when parsing the monitoring format text.

decode_aprs.h

@@ -24,6 +24,8 @@ typedef struct decode_aprs_s {
 
 	int g_quiet;			/* Suppress error messages when decoding. */
 
+	int g_metric;			/* Print metric instead of US customary units */
+
         char g_src[AX25_MAX_ADDR_LEN];
 
         char g_msg_type[60];		/* APRS data type.  Telemetry descriptions get pretty long. */
@@ -135,7 +137,7 @@ typedef struct decode_aprs_s {
 
 
 
-extern void decode_aprs (decode_aprs_t *A, packet_t pp, int quiet);
+extern void decode_aprs (decode_aprs_t *A, packet_t pp, int quiet, int metric);
 
 extern void decode_aprs_print (decode_aprs_t *A);
 

direwolf.c

@@ -176,6 +176,7 @@ static int d_p_opt = 0;			/* "-d p" option for dumping packets over radio. */
 
 static int q_h_opt = 0;			/* "-q h" Quiet, suppress the "heard" line with audio level. */
 static int q_d_opt = 0;			/* "-q d" Quiet, suppress the printing of decoded of APRS packets. */
+static int m_opt = 0;			/* "-m" for metric output. */
 
 
 
@@ -352,7 +353,7 @@ int main (int argc, char *argv[])
 
 	  /* ':' following option character means arg is required. */
 
-          c = getopt_long(argc, argv, "P:B:D:c:pxr:b:n:d:q:t:Ul:L:Sa:E:T:",
+          c = getopt_long(argc, argv, "P:B:D:c:pxr:b:mn:d:q:t:Ul:L:Sa:E:T:",
                         long_options, &option_index);
           if (c == -1)
             break;
@@ -436,6 +437,10 @@ int main (int argc, char *argv[])
    	    }
             break;
 
+	  case 'm':				/* -m set metric */
+	    m_opt = 1;
+	    break;
+
           case 'n':				/* -n number of audio channels for first audio device.  1 or 2. */
 
 	    n_opt = atoi(optarg);
@@ -1089,7 +1094,7 @@ void app_process_rec_packet (int chan, int subchan, int slice, packet_t pp, alev
 	  // we still want to decode it for logging and other processing.
 	  // Just be quiet about errors if "-qd" is set.
 
-	  decode_aprs (&A, pp, q_d_opt);
+	  decode_aprs (&A, pp, q_d_opt, m_opt);
 
 	  if ( ! q_d_opt ) {
 
@@ -1246,6 +1251,7 @@ static void usage (char **argv)
 	dw_printf ("    -c fname       Configuration file name.\n");
 	dw_printf ("    -l logdir      Directory name for log files.  Use . for current.\n");
 	dw_printf ("    -r n           Audio sample rate, per sec.\n");
+	dw_printf ("    -m             Use metric instead of US customary units.\n");
 	dw_printf ("    -n n           Number of audio channels, 1 or 2.\n");
 	dw_printf ("    -b n           Bits per audio sample, 8 or 16.\n");
 	dw_printf ("    -B n           Data rate in bits/sec for channel 0.  Standard values are 300, 1200, 2400, 4800, 9600.\n");

direwolf.h

@@ -168,6 +168,7 @@
 #define DW_METERS_TO_FEET(x) ((x) == G_UNKNOWN ? G_UNKNOWN : (x) * 3.2808399)
 #define DW_FEET_TO_METERS(x) ((x) == G_UNKNOWN ? G_UNKNOWN : (x) * 0.3048)
 #define DW_KM_TO_MILES(x) ((x) == G_UNKNOWN ? G_UNKNOWN : (x) * 0.621371192)
+#define DW_MILES_TO_KM(x) ((x) == G_UNKNOWN ? G_UNKNOWN : (x) * 1.609344)
 
 #define DW_KNOTS_TO_MPH(x) ((x) == G_UNKNOWN ? G_UNKNOWN : (x) * 1.15077945)
 #define DW_KNOTS_TO_METERS_PER_SEC(x) ((x) == G_UNKNOWN ? G_UNKNOWN : (x) * 0.51444444444)

pfilter.c

@@ -200,6 +200,7 @@ int pfilter (int from_chan, int to_chan, char *filter, packet_t pp, int is_aprs)
 	pfstate_t pfstate;
 	char *p;
 	int result;
+	int metric = 0;
 
 	assert (from_chan >= 0 && from_chan <= MAX_CHANS);
 	assert (to_chan >= 0 && to_chan <= MAX_CHANS);
@@ -235,7 +236,7 @@ int pfilter (int from_chan, int to_chan, char *filter, packet_t pp, int is_aprs)
 	pfstate.is_aprs = is_aprs;
 
 	if (is_aprs) {
-	  decode_aprs (&pfstate.decoded, pp, 1);
+	  decode_aprs (&pfstate.decoded, pp, 1, metric);
 	}
 
 	next_token(&pfstate);