Add decode_dm flex option (closes #2241)

README.md

@@ -379,6 +379,7 @@ Available options are:
 	invert : invert all bits
 	reflect : reflect each byte (MSB first to MSB last)
 	decode_uart : UART 8n1 (10-to-8) decode
+	decode_dm : Differential Manchester decode
 	match=<bits> : only match if the <bits> are found
 	preamble=<bits> : match and align at the <bits> preamble
 		<bits> is a row spec of {<bit count>}<bits as hex number>
@@ -415,14 +416,14 @@ E.g. -X "n=doorbell,m=OOK_PWM,s=400,l=800,r=7000,g=1000,match={24}0xa9878c,repea
   [-M time[:<options>]|protocol|level|noise[:<secs>]|stats|bits] Add various metadata to every output line.
 	Use "time" to add current date and time meta data (preset for live inputs).
 	Use "time:rel" to add sample position meta data (preset for read-file and stdin).
-	Use "time:unix" to show the seconds since unix epoch as time meta data.
+	Use "time:unix" to show the seconds since unix epoch as time meta data. This is always UTC.
 	Use "time:iso" to show the time with ISO-8601 format (YYYY-MM-DD"T"hh:mm:ss).
 	Use "time:off" to remove time meta data.
 	Use "time:usec" to add microseconds to date time meta data.
 	Use "time:tz" to output time with timezone offset.
 	Use "time:utc" to output time in UTC.
 		(this may also be accomplished by invocation with TZ environment variable set).
-		"usec" and "utc" can be combined with other options, eg. "time:unix:utc:usec".
+		"usec" and "utc" can be combined with other options, eg. "time:iso:utc" or "time:unix:usec".
 	Use "replay[:N]" to replay file inputs at (N-times) realtime.
 	Use "protocol" / "noprotocol" to output the decoder protocol number meta data.
 	Use "level" to add Modulation, Frequency, RSSI, SNR, and Noise meta data.

man/man1/rtl_433.1

@@ -299,6 +299,9 @@ reflect : reflect each byte (MSB first to MSB last)
 decode_uart : UART 8n1 (10\-to\-8) decode
 .RE
 .RS
+decode_dm : Differential Manchester decode
+.RE
+.RS
 match=<bits> : only match if the <bits> are found
 .RE
 .RS
@@ -382,7 +385,7 @@ Use "time" to add current date and time meta data (preset for live inputs).
 Use "time:rel" to add sample position meta data (preset for read\-file and stdin).
 .RE
 .RS
-Use "time:unix" to show the seconds since unix epoch as time meta data.
+Use "time:unix" to show the seconds since unix epoch as time meta data. This is always UTC.
 .RE
 .RS
 Use "time:iso" to show the time with ISO\-8601 format (YYYY\-MM\-DD"T"hh:mm:ss).
@@ -403,7 +406,7 @@ Use "time:utc" to output time in UTC.
 	(this may also be accomplished by invocation with TZ environment variable set).
 .RE
 .RS
-	"usec" and "utc" can be combined with other options, eg. "time:unix:utc:usec".
+	"usec" and "utc" can be combined with other options, eg. "time:iso:utc" or "time:unix:usec".
 .RE
 .RS
 Use "replay[:N]" to replay file inputs at (N\-times) realtime.

src/devices/flex.c

@@ -97,6 +97,7 @@ struct flex_params {
     uint32_t symbol_sync;
     struct flex_get getter[GETTER_SLOTS];
     unsigned decode_uart;
+    unsigned decode_dm;
     char const *fields[7 + GETTER_SLOTS + 1]; // NOTE: needs to match output_fields
 };
 
@@ -254,6 +255,18 @@ static int flex_callback(r_device *decoder, bitbuffer_t *bitbuffer)
         }
     }
 
+    if (params->decode_dm) {
+        for (i = 0; i < bitbuffer->num_rows; i++) {
+            // TODO: refactor to bitbuffer_decode_dm_row()
+            unsigned len = bitbuffer->bits_per_row[i];
+            bitbuffer_t tmp = {0};
+            bitbuffer_differential_manchester_decode(bitbuffer, i, 0, &tmp, len);
+            len = tmp.bits_per_row[0];
+            memcpy(bitbuffer->bb[i], tmp.bb[0], (len + 7) / 8); // safe to write over: can only be shorter
+            bitbuffer->bits_per_row[i] = len;
+        }
+    }
+
     if (decoder->verbose) {
         fprintf(stderr, "%s: ", params->name);
         bitbuffer_print(bitbuffer);
@@ -399,6 +412,7 @@ static void help(void)
             "\tinvert : invert all bits\n"
             "\treflect : reflect each byte (MSB first to MSB last)\n"
             "\tdecode_uart : UART 8n1 (10-to-8) decode\n"
+            "\tdecode_dm : Differential Manchester decode\n"
             "\tmatch=<bits> : only match if the <bits> are found\n"
             "\tpreamble=<bits> : match and align at the <bits> preamble\n"
             "\t\t<bits> is a row spec of {<bit count>}<bits as hex number>\n"
@@ -664,6 +678,8 @@ r_device *flex_create_device(char *spec)
 
         else if (!strcasecmp(key, "decode_uart"))
             params->decode_uart = val ? atoi(val) : 1;
+        else if (!strcasecmp(key, "decode_dm"))
+            params->decode_dm = val ? atoi(val) : 1;
 
         else if (!strcasecmp(key, "symbol_zero"))
             params->symbol_zero = parse_symbol(val);