Add extract_bytes_uart_parity utility function

include/bit_util.h

@@ -52,7 +52,7 @@ void reflect_nibbles(uint8_t message[], unsigned num_bytes);
 /// @param num_bits message length in bits
 /// @param dst target buffer for extracted nibbles, at least num_bits/5 size
 /// @return number of successfully unstuffed nibbles.
-unsigned extract_nibbles_4b1s(uint8_t *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst);
+unsigned extract_nibbles_4b1s(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst);
 
 /// UART "8n1" (10-to-8) decoder with 1 start bit (0), no parity, 1 stop bit (1), LSB-first bit-order.
 ///
@@ -61,7 +61,16 @@ unsigned extract_nibbles_4b1s(uint8_t *message, unsigned offset_bits, unsigned n
 /// @param num_bits message length in bits
 /// @param dst target buffer for extracted bytes, at least num_bits/10 size
 /// @return number of successful decoded bytes
-unsigned extract_bytes_uart(uint8_t *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst);
+unsigned extract_bytes_uart(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst);
+
+/// UART "8o1" (11-to-8) decoder with 1 start bit (1), odd parity, 1 stop bit (0), MSB-first bit-order.
+///
+/// @param message bytes of message data
+/// @param offset_bits start offset of message in bits
+/// @param num_bits message length in bits
+/// @param dst target buffer for extracted bytes, at least num_bits/11 size
+/// @return number of successful decoded bytes
+unsigned extract_bytes_uart_parity(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst);
 
 /// Decode symbols to bits.
 ///
@@ -73,7 +82,7 @@ unsigned extract_bytes_uart(uint8_t *message, unsigned offset_bits, unsigned num
 /// @param sync symbol for sync bit, ignored at start, terminates at end
 /// @param dst target buffer for extracted bits, at least num_bits/symbol_x_len size
 /// @return number of successful decoded bits
-unsigned extract_bits_symbols(uint8_t *message, unsigned offset_bits, unsigned num_bits, uint32_t zero, uint32_t one, uint32_t sync, uint8_t *dst);
+unsigned extract_bits_symbols(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint32_t zero, uint32_t one, uint32_t sync, uint8_t *dst);
 
 /// CRC-4.
 ///

src/bit_util.c

@@ -26,7 +26,7 @@ uint8_t reverse8(uint8_t x)
 uint32_t reverse32(uint32_t x)
 {
     uint32_t ret;
-    uint8_t* xp = (uint8_t*)&x;
+    uint8_t const* xp = (uint8_t*)&x;
     ret = (uint32_t) reverse8(xp[0]) << 24 | reverse8(xp[1]) << 16 | reverse8(xp[2]) << 8 | reverse8(xp[3]);
     return ret;
 }
@@ -52,7 +52,7 @@ void reflect_nibbles(uint8_t message[], unsigned num_bytes)
     }
 }
 
-unsigned extract_nibbles_4b1s(uint8_t *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst)
+unsigned extract_nibbles_4b1s(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst)
 {
     unsigned ret = 0;
 
@@ -70,7 +70,7 @@ unsigned extract_nibbles_4b1s(uint8_t *message, unsigned offset_bits, unsigned n
     return ret;
 }
 
-unsigned extract_bytes_uart(uint8_t *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst)
+unsigned extract_bytes_uart(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst)
 {
     unsigned ret = 0;
 
@@ -97,7 +97,39 @@ unsigned extract_bytes_uart(uint8_t *message, unsigned offset_bits, unsigned num
     return ret;
 }
 
-static unsigned symbol_match(uint8_t *message, unsigned offset_bits, unsigned num_bits, uint32_t symbol)
+unsigned extract_bytes_uart_parity(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst)
+{
+    unsigned ret = 0;
+
+    while (num_bits >= 11) {
+        int startb = message[offset_bits / 8] >> (7 - (offset_bits % 8));
+        offset_bits += 1;
+        int datab = message[offset_bits / 8];
+        if (offset_bits % 8) {
+            datab = (message[offset_bits / 8] << 8) | message[offset_bits / 8 + 1];
+            datab >>= 8 - (offset_bits % 8);
+        }
+        offset_bits += 8;
+        int parityb = message[offset_bits / 8] >> (7 - (offset_bits % 8));
+        offset_bits += 1;
+        int stopb = message[offset_bits / 8] >> (7 - (offset_bits % 8));
+        offset_bits += 1;
+        int data_parity = parity8(datab);
+        if ((startb & 1) != 1)
+            break; // start-bit error
+        if ((parityb & 1) != data_parity)
+            break; // parity-bit error
+        if ((stopb & 1) != 0)
+            break; // stop-bit error
+        *dst++ = (datab & 0xff);
+        ret += 1;
+        num_bits -= 11;
+    }
+
+    return ret;
+}
+
+static unsigned symbol_match(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint32_t symbol)
 {
     unsigned symbol_len = symbol & 0x1f;
 
@@ -119,7 +151,7 @@ static unsigned symbol_match(uint8_t *message, unsigned offset_bits, unsigned nu
     return symbol_len;
 }
 
-unsigned extract_bits_symbols(uint8_t *message, unsigned offset_bits, unsigned num_bits, uint32_t zero, uint32_t one, uint32_t sync, uint8_t *dst)
+unsigned extract_bits_symbols(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint32_t zero, uint32_t one, uint32_t sync, uint8_t *dst)
 {
     unsigned zero_len = zero & 0x1f;
     unsigned one_len  = one & 0x1f;

src/devices/rosstech_dcu706.c

@@ -18,6 +18,10 @@ Supported Models:
 Sundance DCU-6560-131, SD-880 Series, PN 6560-131
 Jacuzzi DCU-2560-131, Jac-J300/J400 and SD-780 series, PN 6560-132/2560-131
 
+Data coding:
+
+UART 8o1: 11 bits/byte: 1 start bit (1), odd parity, 1 stop bit (0).
+
 Data layout:
 
     SS IIII TT CC
@@ -28,29 +32,8 @@ Data layout:
 - C: 8 bit Checksum: Count 1s for each bit of each element:
                      Set bit to 1 if number is even 0 if odd
 
-11 bits/byte: 1 start bit, 0 stop bits and odd parity
-
 */
 
-static uint8_t calculateChecksum(const uint8_t *data, size_t size)
-{
-    uint8_t checksum = 0;
-
-    for (int bit = 0; bit < 8; bit++) {
-        int count = 0;
-
-        for (size_t i = 0; i < size; i++) {
-            count += (data[i] >> bit) & 1;
-        }
-
-        if (count % 2 == 0) {
-            checksum |= (1 << bit);
-        }
-    }
-
-    return checksum;
-}
-
 static int rosstech_dcu706_decode(r_device *decoder, bitbuffer_t *bitbuffer)
 {
     uint8_t const preamble_data_transmission[] = {0xDD, 0x40};
@@ -85,23 +68,21 @@ static int rosstech_dcu706_decode(r_device *decoder, bitbuffer_t *bitbuffer)
 
     bitbuffer_extract_bytes(bitbuffer, 0, start_pos, msg, sizeof(msg) * 8);
 
-    uint8_t msg_type = (msg[0] << 1) | (msg[1] >> 7); // S
+    uint8_t b[5] = {0};
-    uint8_t id_high  = (msg[1] << 4) | (msg[2] >> 4);
+    unsigned r   = extract_bytes_uart_parity(msg, 0, 55, b);
-    uint8_t id_low   = (msg[2] << 7) | (msg[3] >> 1);
+    if (r != 5) {
-    uint16_t id      = (id_high << 8) | id_low;       // I
+        decoder_logf(decoder, 2, __func__, "UART decoding failed. Got %d of 5 bytes", r);
-    uint8_t temp_f   = (msg[4] << 2) | (msg[5] >> 6); // T
+        return DECODE_ABORT_LENGTH;
-    uint8_t checksum = (msg[5] << 5) | (msg[6] >> 3); // C
+    }
 
-    // Create a uint8_t array to hold the extracted values
+    int msg_type = b[0];                 // S
-    uint8_t extracted_data[4];
+    int id       = (b[1] << 8) | (b[2]); // I
-    extracted_data[0] = msg_type;
+    int temp_f   = b[3];                 // T
-    extracted_data[1] = id_high;
+    int checksum = b[4];                 // C
-    extracted_data[2] = id_low;
-    extracted_data[3] = temp_f;
 
-    uint8_t calculated_checksum = calculateChecksum(extracted_data, sizeof(extracted_data) / sizeof(extracted_data[0]));
+    uint8_t calculated = 0xff ^ xor_bytes(b, 4);
-    if (calculated_checksum != checksum) {
+    if (calculated != checksum) {
-        decoder_logf(decoder, 2, __func__, "Checksum failed. Expected: %02x, Calculated: %02x.", checksum, calculated_checksum);
+        decoder_logf(decoder, 2, __func__, "Checksum failed. Expected: %02x, Calculated: %02x", checksum, calculated);
         return DECODE_FAIL_MIC;
     }