Add extract_bytes_uart_8n2 util (#3422)

Author: zuckschwerdt

README.md

@@ -478,7 +478,7 @@ Available options are:
 		use opt>=n to match at least <n> and opt<=n to match at most <n>
 	invert : invert all bits
 	reflect : reflect each byte (MSB first to MSB last)
-	decode_uart : UART 8n1 (10-to-8) decode
+	decode_uart=<8n1|8n2|8o1> : UART 8n1 (10-to-8), 8n2, 8o1 (11-to-8) decode
 	decode_dm : Differential Manchester decode
 	decode_mc : Manchester decode
 	match=<bits> : only match if the <bits> are found

include/bit_util.h

@@ -61,7 +61,18 @@ unsigned extract_nibbles_4b1s(uint8_t const *message, unsigned offset_bits, unsi
 /// @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 const *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst);
+unsigned extract_bytes_uart_8n1(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst);
+
+/// UART "8n2" (11-to-8) decoder with 1 start bit (0), no parity, 2 stop bits (1), LSB-first bit-order.
+///
+/// Skips (1) bits until the first start bit (0) is found.
+///
+/// @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_8n2(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.
 ///
@@ -70,7 +81,7 @@ unsigned extract_bytes_uart(uint8_t const *message, unsigned offset_bits, unsign
 /// @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);
+unsigned extract_bytes_uart_8o1(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst);
 
 /// Decode symbols to bits.
 ///

man/man1/rtl_433.1

@@ -301,7 +301,7 @@ invert : invert all bits
 reflect : reflect each byte (MSB first to MSB last)
 .RE
 .RS
-decode_uart : UART 8n1 (10\-to\-8) decode
+decode_uart=<8n1|8n2|8o1> : UART 8n1 (10\-to\-8), 8n2, 8o1 (11\-to\-8) decode
 .RE
 .RS
 decode_dm : Differential Manchester decode

src/bit_util.c

@@ -70,7 +70,7 @@ unsigned extract_nibbles_4b1s(uint8_t const *message, unsigned offset_bits, unsi
     return ret;
 }
 
-unsigned extract_bytes_uart(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst)
+unsigned extract_bytes_uart_8n1(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst)
 {
     unsigned ret = 0;
 
@@ -97,7 +97,48 @@ unsigned extract_bytes_uart(uint8_t const *message, unsigned offset_bits, unsign
     return ret;
 }
 
-unsigned extract_bytes_uart_parity(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst)
+unsigned extract_bytes_uart_8n2(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst)
+{
+    unsigned ret = 0;
+
+    // skip until first start bit
+    while (num_bits > 11) {
+        int startb = message[offset_bits / 8] >> (7 - (offset_bits % 8));
+        if ((startb & 1) == 0) {
+            break; // start bit found
+        }
+        offset_bits += 1;
+        num_bits -= 1;
+    }
+    // get framed bytes
+    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 stopb1 = message[offset_bits / 8] >> (7 - (offset_bits % 8));
+        offset_bits += 1;
+        int stopb2 = message[offset_bits / 8] >> (7 - (offset_bits % 8));
+        offset_bits += 1;
+        if ((startb & 1) != 0)
+            break; // start-bit error
+        if ((stopb1 & 1) != 1)
+            break; // stop-bit error
+        if ((stopb2 & 1) != 1)
+            break; // stop-bit error
+        *dst++ = reverse8(datab & 0xff);
+        ret += 1;
+        num_bits -= 11;
+    }
+
+    return ret;
+}
+
+unsigned extract_bytes_uart_8o1(uint8_t const *message, unsigned offset_bits, unsigned num_bits, uint8_t *dst)
 {
     unsigned ret = 0;
 
@@ -568,18 +609,28 @@ int main(void) {
     // y0 xff y1 y0 xcc y1 y0 x80 y1 y0 x40 y1 y0 xc0 y1
     uint8_t uart123[] = {0x07, 0xfd, 0x99, 0x40, 0x48, 0x16, 0x04, 0x00};
 
-    fprintf(stderr, "util::extract_bytes_uart():\n");
-    ASSERT_EQUALS(extract_bytes_uart(uart, 0, 24, bytes), 2);
+    fprintf(stderr, "util::extract_bytes_uart_8n1():\n");
+    ASSERT_EQUALS(extract_bytes_uart_8n1(uart, 0, 24, bytes), 2);
     ASSERT_EQUALS(bytes[0], 0xff);
     ASSERT_EQUALS(bytes[1], 0x33);
 
-    ASSERT_EQUALS(extract_bytes_uart(uart123, 4, 60, bytes), 5);
+    ASSERT_EQUALS(extract_bytes_uart_8n1(uart123, 4, 60, bytes), 5);
     ASSERT_EQUALS(bytes[0], 0xff);
     ASSERT_EQUALS(bytes[1], 0x33);
     ASSERT_EQUALS(bytes[2], 0x01);
     ASSERT_EQUALS(bytes[3], 0x02);
     ASSERT_EQUALS(bytes[4], 0x03);
 
+    // y0 xD1 y11  y0 x11 y11  y0 x4D y11  y0 xEE y11
+    uint8_t uart8n2[] = {0x45, 0xe8, 0x8d, 0x65, 0x9d, 0xf0};
+
+    fprintf(stderr, "util::extract_bytes_uart_8n2():\n");
+    ASSERT_EQUALS(extract_bytes_uart_8n2(uart8n2, 0, 44, bytes), 4);
+    ASSERT_EQUALS(bytes[0], 0xd1);
+    ASSERT_EQUALS(bytes[1], 0x11);
+    ASSERT_EQUALS(bytes[2], 0x4d);
+    ASSERT_EQUALS(bytes[3], 0xee);
+
     fprintf(stderr, "util::ccitt_whitening():\n");
     uint8_t buf1[16] = {0};
     uint8_t chk1[16] = {0xff, 0x87, 0xb8, 0x59, 0xb7, 0xa1, 0xcc, 0x24, 0x57, 0x5e, 0x4b, 0x9c, 0x0e, 0xe9, 0xea, 0x50};

src/devices/flex.c

@@ -14,6 +14,12 @@
 #include "fatal.h"
 #include <stdlib.h>
 
+enum uart_mode {
+    UART_MODE_8N1 = 1,
+    UART_MODE_8N2,
+    UART_MODE_8O1,
+};
+
 static inline int bit(const uint8_t *bytes, unsigned b)
 {
     return bytes[b >> 3] >> (7 - (b & 7)) & 1;
@@ -240,7 +246,13 @@ static int flex_callback(r_device *decoder, bitbuffer_t *bitbuffer)
             // TODO: refactor to bitbuffer_decode_uart_row()
             unsigned len = bitbuffer->bits_per_row[i];
             bitbuffer_t tmp = {0};
-            len = extract_bytes_uart(bitbuffer->bb[i], 0, len, tmp.bb[0]);
+            if (params->decode_uart == UART_MODE_8N1) {
+                len = extract_bytes_uart_8n1(bitbuffer->bb[i], 0, len, tmp.bb[0]);
+            } else if (params->decode_uart == UART_MODE_8N2) {
+                len = extract_bytes_uart_8n2(bitbuffer->bb[i], 0, len, tmp.bb[0]);
+            } else if (params->decode_uart == UART_MODE_8O1) {
+                len = extract_bytes_uart_8o1(bitbuffer->bb[i], 0, len, tmp.bb[0]);
+            }
             memcpy(bitbuffer->bb[i], tmp.bb[0], len); // safe to write over: can only be shorter
             bitbuffer->bits_per_row[i] = len * 8;
         }
@@ -418,7 +430,7 @@ static void help(void)
             "\t\tuse opt>=n to match at least <n> and opt<=n to match at most <n>\n"
             "\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_uart=<8n1|8n2|8o1> : UART 8n1 (10-to-8), 8n2, 8o1 (11-to-8) decode\n"
             "\tdecode_dm : Differential Manchester decode\n"
             "\tdecode_mc : Manchester decode\n"
             "\tmatch=<bits> : only match if the <bits> are found\n"
@@ -630,6 +642,21 @@ static void parse_getter(const char *arg, struct flex_get *getter)
     */
 }
 
+static unsigned parse_uart_mode(char const *str)
+{
+    if (!strcasecmp(str, "8n1"))
+        return UART_MODE_8N1;
+    else if (!strcasecmp(str, "8n2"))
+        return UART_MODE_8N2;
+    else if (!strcasecmp(str, "8o1"))
+        return UART_MODE_8O1;
+    else {
+        fprintf(stderr, "Bad flex spec, unknown uart mode!\n");
+        usage();
+    }
+    return 0;
+}
+
 // NOTE: this is declared in rtl_433.c also.
 r_device *flex_create_device(char *spec);
 
@@ -728,7 +755,7 @@ r_device *flex_create_device(char *spec)
             params->unique = parse_atoiv(val, 1, "unique: ");
 
         else if (!strcasecmp(key, "decode_uart"))
-            params->decode_uart = parse_atoiv(val, 1, "decode_uart: ");
+            params->decode_uart = parse_uart_mode(val);
         else if (!strcasecmp(key, "decode_dm"))
             params->decode_dm = parse_atoiv(val, 1, "decode_dm: ");
         else if (!strcasecmp(key, "decode_mc"))

src/devices/gridstream.c

@@ -141,12 +141,12 @@ static int gridstream_decode(r_device *decoder, bitbuffer_t *bitbuffer)
             return DECODE_FAIL_SANITY;
         }
         unsigned num_bits = MIN(bitbuffer->bits_per_row[0] - offset, sizeof(b) * 10);
-        decoded_len       = extract_bytes_uart(bitbuffer->bb[0], offset, num_bits, b);
+        decoded_len       = extract_bytes_uart_8n1(bitbuffer->bb[0], offset, num_bits, b);
         protocol_version  = 5;
     }
     else {
         unsigned num_bits = MIN(bitbuffer->bits_per_row[0] - offset, sizeof(b) * 10);
-        decoded_len       = extract_bytes_uart(bitbuffer->bb[0], offset, num_bits, b);
+        decoded_len       = extract_bytes_uart_8n1(bitbuffer->bb[0], offset, num_bits, b);
         protocol_version  = 4;
     }
 

src/devices/rosstech_dcu706.c

@@ -69,7 +69,7 @@ static int rosstech_dcu706_decode(r_device *decoder, bitbuffer_t *bitbuffer)
     bitbuffer_extract_bytes(bitbuffer, 0, start_pos, msg, sizeof(msg) * 8);
 
     uint8_t b[5] = {0};
-    unsigned r   = extract_bytes_uart_parity(msg, 0, 55, b);
+    unsigned r   = extract_bytes_uart_8o1(msg, 0, 55, b);
     if (r != 5) {
         decoder_logf(decoder, 2, __func__, "UART decoding failed. Got %d of 5 bytes", r);
         return DECODE_ABORT_LENGTH;

src/devices/sainlogic_sa8.c

@@ -81,7 +81,7 @@ static int sainlogic_sa8_decode(r_device *decoder, bitbuffer_t *bitbuffer)
 
     int num_bits = bitbuffer->bits_per_row[0] - offset;
     num_bits = MIN((size_t)num_bits, sizeof (b) * 10);
-    int len = extract_bytes_uart(bitbuffer->bb[0], offset, num_bits, b);
+    int len = extract_bytes_uart_8n1(bitbuffer->bb[0], offset, num_bits, b);
 
     if (len < 41) {
         decoder_log(decoder, 2, __func__, "Message too short");

src/devices/somfy_iohc.c

@@ -107,7 +107,7 @@ static int somfy_iohc_decode(r_device *decoder, bitbuffer_t *bitbuffer)
 
     num_bits = MIN((size_t)num_bits, sizeof (b) * 10);
 
-    int len = extract_bytes_uart(bitbuffer->bb[0], offset, num_bits, b);
+    int len = extract_bytes_uart_8n1(bitbuffer->bb[0], offset, num_bits, b);
     if (len < 11)
         return DECODE_ABORT_LENGTH;