Add 16-bit CCITT CRC implementation.

src/utils/Crc.cxx

@@ -222,7 +222,7 @@ void crc3_crc16_ibm(const void* data, size_t length_bytes, uint16_t* checksum)
 }
 
 // static
-uint8_t Crc8DallasMaxim::table256[256] =
+const uint8_t Crc8DallasMaxim::table256[256] =
 {
     0x00, 0x5e, 0xbc, 0xe2, 0x61, 0x3f, 0xdd, 0x83,
     0xc2, 0x9c, 0x7e, 0x20, 0xa3, 0xfd, 0x1f, 0x41,
@@ -259,15 +259,63 @@ uint8_t Crc8DallasMaxim::table256[256] =
 };
 
 // static
-uint8_t Crc8DallasMaxim::tableLo16[16] =
+const uint8_t Crc8DallasMaxim::tableLo16[16] =
 {
     0x00, 0x5e, 0xbc, 0xe2, 0x61, 0x3f, 0xdd, 0x83,
     0xc2, 0x9c, 0x7e, 0x20, 0xa3, 0xfd, 0x1f, 0x41,
 };
 
 // static
-uint8_t Crc8DallasMaxim::tableHi16[16] =
+const uint8_t Crc8DallasMaxim::tableHi16[16] =
 {
     0x00, 0x9d, 0x23, 0xbe, 0x46, 0xdb, 0x65, 0xf8,
     0x8c, 0x11, 0xaf, 0x32, 0xca, 0x57, 0xe9, 0x74
 };
+
+const uint16_t Crc16CCITT::table256[256] =
+{
+    0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
+    0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
+    0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
+    0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
+    0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
+    0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
+    0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
+    0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
+    0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
+    0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
+    0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
+    0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
+    0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
+    0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
+    0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
+    0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
+    0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
+    0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
+    0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
+    0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
+    0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
+    0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
+    0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
+    0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
+    0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
+    0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
+    0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
+    0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
+    0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
+    0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
+    0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
+    0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
+};
+
+const uint16_t Crc16CCITT::tableLo16[16] =
+{
+    0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
+    0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF
+};
+
+const uint16_t Crc16CCITT::tableHi16[16] =
+{
+    0x0000, 0x1231, 0x2462, 0x3653, 0x48C4, 0x5AF5, 0x6CA6, 0x7E97,
+    0x9188, 0x83B9, 0xB5EA, 0xA7DB, 0xD94C, 0xCB7D, 0xFD2E, 0xEF1F
+};

src/utils/Crc.cxxtest

@@ -248,3 +248,60 @@ TEST(Crc8Test, LogonExample4)
     m.update256(0xaa);
     LOG(INFO, "example: 0x%02x", m.get());
 }
+
+TEST(CRC16CCITTTest, Example)
+{
+    std::basic_string<uint8_t> vector =
+    {
+        '1', '2', '3', '4', '5', '6', '7', '8', '9'
+    };
+
+    printf("sizeof(vector): %zu\n", sizeof(vector));
+    Crc16CCITT crc;
+    crc.crc(vector.data(), vector.size());
+    EXPECT_EQ(0x29B1U, crc.get());
+
+    crc.init();
+    for (unsigned i = 0; i < vector.size(); ++i)
+    {
+        crc.update16(vector[i]);
+    }
+    EXPECT_EQ(0x29B1U, crc.get());
+
+    crc.init();
+    for (unsigned i = 0; i < vector.size(); ++i)
+    {
+        crc.update256(vector[i]);
+    }
+    EXPECT_EQ(0x29B1U, crc.get());
+}
+
+TEST(CRC16CCITTTest, ExampleCRC3)
+{
+    {
+        // Even number of bytes.
+        const uint8_t vector[] =
+        {
+            0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08
+        };
+        uint16_t results[3];
+        crc3_crc16_ccitt(vector, sizeof(vector), results);
+        EXPECT_EQ(0x4792, results[0]);
+        EXPECT_EQ(0x2436, results[1]);
+        EXPECT_EQ(0x9EC6, results[2]);
+    }
+
+    {
+        // Odd number of bytes.
+        const uint8_t vector[] =
+        {
+            0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B
+        };
+        uint16_t results[3];
+        crc3_crc16_ccitt(vector, sizeof(vector), results);
+        EXPECT_EQ(0x6989, results[0]);
+        EXPECT_EQ(0x23ED, results[1]);
+        EXPECT_EQ(0xF408, results[2]);
+    }
+
+}

src/utils/Crc.hxx

@@ -38,6 +38,16 @@
 #include <stdint.h>
 #include <stddef.h>
 
+#ifndef CRC8DALLAS_TABLE_SIZE
+/// Use the smaller (slower) table by default.
+#define CRC8DALLAS_TABLE_SIZE 16
+#endif
+#ifndef CRC16CCITT_TABLE_SIZE
+/// Use the larger (faster) table by default.
+#define CRC16CCITT_TABLE_SIZE 256
+#endif
+
+
 /** Computes the 16-bit CRC value over data using the CRC16-ANSI (aka
  * CRC16-IBM) settings. This involves zero init value, zero terminating value,
  * reversed polynomial 0xA001, reversing input bits and reversing output
@@ -63,7 +73,6 @@ uint16_t crc_16_ibm(const void* data, size_t length_bytes);
  */
 void crc3_crc16_ibm(const void* data, size_t length_bytes, uint16_t* checksum);
 
-
 /// Helper class for computing CRC-8 according to Dallas/Maxim specification
 /// for 1-wire protocol. This specification is used for BiDiB, RCN-218 and
 /// S-9.2.1.1.
@@ -166,29 +175,180 @@ public:
         state_ = table256[state_ ^ message_byte];
     }
 
-#ifdef CRC8_TABLE_SIZE
     /// Processes one byte of the incoming message.
     /// @param message_byte next byte in the message.
     void update(uint8_t message_byte)
     {
-        update##CRC8_TABLE_SIZE(message_byte);
-    }
+#if CRC8DALLAS_TABLE_SIZE == 0
+        update0(message_byte);
+#elif CRC8DALLAS_TABLE_SIZE == 16
+        update16(message_byte);
+#elif CRC8DALLAS_TABLE_SIZE == 256
+        update256(message_byte);
+#else
+#error "Invalid value for CRC16CCITT_TABLE_SIZE"
 #endif
+    }
 
 private:
     // Of the static tables here only those will be linked into a binary which
     // have been used there.
-    
+
     /// 256-entry lookup table for the update256 function.
-    static uint8_t table256[256];
+    static const uint8_t table256[256];
 
     /// 16-entry lookup table for the update16 function.
-    static uint8_t tableHi16[16];
+    static const uint8_t tableHi16[16];
+
     /// 16-entry lookup table for the update16 function.
-    static uint8_t tableLo16[16];
-    
+    static const uint8_t tableLo16[16];
+
     /// Current value of the state register for the CRC computation.
     uint8_t state_;
-};
+}; // Crc8DallasMaxim
+
+/// Helper class for computing CRC-16 according to the CCITT specification
+/// (polynomial = 0x1021, x^16 + x^12 + x^5 + 1, initial value = 0xFFFF).
+///
+/// This class can incrementally compute CRC byte by byte. There are two
+/// implementations available, with different code space requirements.
+class Crc16CCITT
+{
+public:
+    Crc16CCITT()
+        : state_(0xFFFF)
+    {
+    }
+
+    /// Re-sets the state machine for checksumming a new message.
+    void init()
+    {
+        state_ = 0xFFFF;
+    }
+
+    /// @return the checksum of the currently consumed message.
+    uint16_t get()
+    {
+        return state_;
+    }
+
+    /// Checks that the message has a correct CRC. This function assumes that
+    /// the CRC byte has already been consumed.
+    /// @return true if the message checksum is correct.
+    bool check_ok()
+    {
+        return (state_ == 0);
+    }
+
+    /// Checks that the message has a correct CRC. This function assumes that
+    /// the CRC byte was not part of the message.
+    /// @param checksum the CRC16 of the received message.
+    /// @return true if the message checksum is correct.
+    bool check_ok(uint16_t checksum)
+    {
+        return (state_ == checksum);
+    }
+
+    /// Processes one byte of the incoming message. A small lookup table will be
+    /// used.
+    /// @param message_byte next byte in the message.
+    void update16(uint8_t message_byte)
+    {
+        uint8_t data = (state_ >> 8) ^ message_byte;
+        state_ = (state_ << 8) ^
+            tableLo16[data & 0xF] ^ tableHi16[data >> 4];
+    }
+
+    /// Processes one byte of the incoming message. A 256-byte lookup table
+    /// will be used.
+    /// @param message_byte next byte in the message.
+    void update256(uint8_t message_byte)
+    {
+        state_ = (state_ << 8) ^ table256[(state_ >> 8) ^ message_byte];
+    }
+
+    /// Processes one byte of the incoming message.
+    /// @param message_byte next byte in the message.
+    void update(uint8_t message_byte)
+    {
+#if CRC16CCITT_TABLE_SIZE == 16
+        update16(message_byte);
+#elif CRC16CCITT_TABLE_SIZE == 256
+        update256(message_byte);
+#else
+#error "Invalid value for CRC16CCITT_TABLE_SIZE"
+#endif
+    }
+
+    /// Computes the 16-bit CRC value over data
+    /// @param data what to compute the checksum over
+    /// @param length_bytes how long data is
+    void crc(const void* data, size_t length_bytes)
+    {
+        const uint8_t *payload = static_cast<const uint8_t*>(data);
+        init();
+        for (size_t i = 0; i < length_bytes; ++i)
+        {
+            update(payload[i]);
+        }
+    }
+
+private:
+    // Of the static tables here only those will be linked into a binary which
+    // have been used there.
+
+    /// 256-entry lookup table for the update256 function.
+    static const uint16_t table256[256];
+
+    /// 16-entry lookup table for the update16 function.
+    static const uint16_t tableHi16[16];
+
+    /// 16-entry lookup table for the update16 function.
+    static const uint16_t tableLo16[16];
+
+    /// Current value of the state register for the CRC computation.
+    uint16_t state_;
+}; // Crc16CCITT
+
+/// Computes the triple-CRC value over a chunk of data. checksum is an array of
+/// 3 halfwords. The first halfword will get the CRC of the data array, the
+/// second halfword the CRC of all even index bytes (starting with the first
+/// byte, index 0), the third halfword will get the CRC of all odd index bytes
+/// (starting with the the second byte, index 1).
+///
+/// This implementation has no requirements for starting alignment or size
+/// modulus. It will work on any number of bytes.
+///
+/// @param data what to compute the checksum over
+/// @param length_bytes how long data is
+/// @param checksum is the output buffer where to store the 48-bit checksum.
+static inline void crc3_crc16_ccitt(
+    const void* data, size_t length_bytes, uint16_t checksum[3])
+{
+    const uint8_t* payload = static_cast<const uint8_t*>(data);
+
+    Crc16CCITT crc_all;
+    Crc16CCITT crc_even;
+    Crc16CCITT crc_odd;
+
+    for (size_t i = 0; i < length_bytes; ++i)
+    {
+        crc_all.update(payload[i]);
+        if (i & 0x1)
+        {
+            // odd index bytes
+            crc_odd.update(payload[i]);
+        }
+        else
+        {
+            // even index byte
+            crc_even.update(payload[i]);
+        }
+    }
+
+    checksum[0] = crc_all.get();
+    checksum[1] = crc_even.get();
+    checksum[2] = crc_odd.get();
+}
 
-#endif // _UTILS_CRC_HXX_
+#endif // _UTILS_CRC_HXX_