minor: Cleanup LaCrosse-TX style, add TFA 30.3121 note

src/devices/lacrosse.c

@@ -8,11 +8,12 @@
     the Free Software Foundation; either version 2 of the License, or
     (at your option) any later version.
 */
-/** @fn int lacrossetx_decode(r_device *decoder, bitbuffer_t *bitbuffer)
+/**
 LaCrosse TX 433 Mhz Temperature and Humidity Sensors.
 - Tested: TX-7U and TX-6U (Temperature only)
 - Not Tested but should work: TX-3, TX-4
 - also TFA Dostmann 30.3120.90 sensor (for e.g. 35.1018.06 (WS-9015) station)
+- also TFA Dostmann 30.3121 sensor
 
 Protocol Documentation: http://www.f6fbb.org/domo/sensors/tx3_th.php
 
@@ -37,50 +38,51 @@ Message is 44 bits, 11 x 4 bit nybbles:
 - Frequency for each sensor may be could be off by as much as 50-75 khz
 - LaCrosse Sensors in other frequency ranges (915 Mhz) use FSK not OOK
   so they can't be decoded by rtl_433 currently.
+- Temperature and Humidity are sent in different messages bursts.
 
-TO DO:
-- Now that we have a demodulator that isn't stripping the first bit
-  the detect and decode could be collapsed into a single reasonably
-  readable function.
 */
 
 #include "decoder.h"
 
 #define LACROSSE_TX_BITLEN        44
 #define LACROSSE_NYBBLE_CNT        11
 
-// Check for a valid LaCrosse TX Packet
-//
-// Return message nybbles broken out into bytes
-// for clarity.  The LaCrosse protocol is based
-// on 4 bit nybbles.
-//
-// Demodulation
-// Long bits = 0
-// short bits = 1
-//
-static int lacrossetx_detect(r_device *decoder, uint8_t *pRow, uint8_t *msg_nybbles, int16_t rowlen)
+static int lacrossetx_decode(r_device *decoder, bitbuffer_t *bitbuffer)
 {
-    int i;
-    uint8_t rbyte_no, rbit_no, mnybble_no, mbit_no;
-    uint8_t bit, checksum, parity_bit, parity = 0;
+    int events = 0;
+    int result = 0;
 
-    // Actual Packet should start with 0x0A and be 6 bytes
-    // actual message is 44 bit, 11 x 4 bit nybbles.
-    if (rowlen == LACROSSE_TX_BITLEN && pRow[0] == 0x0a) {
+    for (int row = 0; row < bitbuffer->num_rows; ++row) {
+        // break out the message nybbles into separate bytes
+        // The LaCrosse protocol is based on 4 bit nybbles.
+        uint8_t *pRow = bitbuffer->bb[row];
+        uint8_t msg_nybbles[LACROSSE_NYBBLE_CNT];
+        int16_t rowlen = bitbuffer->bits_per_row[row];
+
+        // Actual Packet should start with 0x0A and be 6 bytes
+        // actual message is 44 bit, 11 x 4 bit nybbles.
+        if (rowlen != LACROSSE_TX_BITLEN) {
+            result = DECODE_ABORT_LENGTH;
+            continue; // DECODE_ABORT_LENGTH
+        }
+        if (pRow[0] != 0x0a) {
+            result = DECODE_ABORT_EARLY;
+            continue; // DECODE_ABORT_EARLY
+        }
 
-        for (i = 0; i < LACROSSE_NYBBLE_CNT; i++) {
+        for (int i = 0; i < LACROSSE_NYBBLE_CNT; i++) {
             msg_nybbles[i] = 0;
         }
 
         // Move nybbles into a byte array
         // Compute parity and checksum at the same time.
-        for (i = 0; i < 44; i++) {
-            rbyte_no = i / 8;
-            rbit_no = 7 - (i % 8);
-            mnybble_no = i / 4;
-            mbit_no = 3 - (i % 4);
-            bit = (pRow[rbyte_no] & (1 << rbit_no)) ? 1 : 0;
+        uint8_t parity = 0;
+        for (int i = 0; i < 44; i++) {
+            uint8_t rbyte_no = i / 8;
+            uint8_t rbit_no = 7 - (i % 8);
+            uint8_t mnybble_no = i / 4;
+            uint8_t mbit_no = 3 - (i % 4);
+            uint8_t bit = (pRow[rbyte_no] & (1 << rbit_no)) ? 1 : 0;
             msg_nybbles[mnybble_no] |= (bit << mbit_no);
 
             // Check parity on three bytes of data value
@@ -90,50 +92,28 @@ static int lacrossetx_detect(r_device *decoder, uint8_t *pRow, uint8_t *msg_nybb
                 parity += bit;
             }
 
-            //            decoder_logf(decoder, 0, __func__, "recv: [%d/%d] %d -> msg [%d/%d] %02x, Parity: %d %s", rbyte_no, rbit_no,
-            //                    bit, mnybble_no, mbit_no, msg_nybbles[mnybble_no], parity,
-            //                    ( mbit_no == 0 ) ? "\n" : "" );
+            //decoder_logf(decoder, 0, __func__, "recv: [%d/%d] %d -> msg [%d/%d] %02x, Parity: %d %s", rbyte_no, rbit_no,
+            //        bit, mnybble_no, mbit_no, msg_nybbles[mnybble_no], parity,
+            //        ( mbit_no == 0 ) ? "\n" : "" );
         }
 
-        parity_bit = msg_nybbles[4] & 0x01;
+        uint8_t parity_bit = msg_nybbles[4] & 0x01;
         parity += parity_bit;
 
         // Validate Checksum (4 bits in last nybble)
-        checksum = 0;
-        for (i = 0; i < 10; i++) {
+        uint8_t checksum = 0;
+        for (int i = 0; i < 10; i++) {
             checksum = (checksum + msg_nybbles[i]) & 0x0F;
         }
 
         // decoder_logf(decoder, 0, __func__,"Parity: %d, parity bit %d, Good %d", parity, parity_bit, parity % 2);
 
-        if (checksum == msg_nybbles[10] && (parity % 2 == 0)) {
-            return 1;
-        } else {
+        if (checksum != msg_nybbles[10] || (parity % 2 != 0)) {
             decoder_logf(decoder, 2, __func__,
                     "LaCrosse TX Checksum/Parity error: Comp. %d != Recv. %d, Parity %d",
                     checksum, msg_nybbles[10], parity);
-            return DECODE_FAIL_MIC;
-        }
-    }
-
-    return DECODE_ABORT_LENGTH;
-}
-
-// LaCrosse TX-6u, TX-7u,  Temperature and Humidity Sensors
-// Temperature and Humidity are sent in different messages bursts.
-static int lacrossetx_decode(r_device *decoder, bitbuffer_t *bitbuffer)
-{
-    int events = 0;
-    uint8_t msg_nybbles[LACROSSE_NYBBLE_CNT];
-    data_t *data;
-
-    int result = 0;
-
-    for (int row = 0; row < bitbuffer->num_rows; ++row) {
-        // break out the message nybbles into separate bytes
-        if (lacrossetx_detect(decoder, bitbuffer->bb[row], msg_nybbles, bitbuffer->bits_per_row[row]) <= 0) {
-            result = DECODE_ABORT_EARLY;
-            continue; // DECODE_ABORT_EARLY
+            result = DECODE_FAIL_MIC;
+            continue; // DECODE_FAIL_MIC
         }
 
         // TODO: check if message length is a valid value
@@ -157,7 +137,7 @@ static int lacrossetx_decode(r_device *decoder, bitbuffer_t *bitbuffer)
         if (msg_type == 0x00) {
             float temp_c = msg_value - 50.0f;
             /* clang-format off */
-            data = data_make(
+            data_t *data = data_make(
                     "model",            "",             DATA_STRING, "LaCrosse-TX",
                     "id",               "",             DATA_INT,    sensor_id,
                     "temperature_C",    "Temperature",  DATA_FORMAT, "%.1f C", DATA_DOUBLE, temp_c,
@@ -169,7 +149,7 @@ static int lacrossetx_decode(r_device *decoder, bitbuffer_t *bitbuffer)
         }
         else if (msg_type == 0x0E) {
             /* clang-format off */
-            data = data_make(
+            data_t *data = data_make(
                     "model",            "",             DATA_STRING, "LaCrosse-TX",
                     "id",               "",             DATA_INT,    sensor_id,
                     "humidity",         "Humidity",     DATA_FORMAT, "%.1f %%", DATA_DOUBLE, msg_value,
@@ -187,8 +167,9 @@ static int lacrossetx_decode(r_device *decoder, bitbuffer_t *bitbuffer)
         }
     }
 
-    if (events)
+    if (events) {
         return events;
+    }
 
     return result;
 }