Added DataTypeSignatureCRC

libuavcan/include/uavcan/internal/data_type.hpp

@@ -4,6 +4,7 @@
 
 #pragma once
 
+#include <cassert>
 #include <stdint.h>
 #include <algorithm>
 
@@ -17,6 +18,40 @@ enum DataTypeKind
     NumDataTypeKinds
 };
 
+/**
+ * CRC-64-WE
+ * Description: http://reveng.sourceforge.net/crc-catalogue/17plus.htm#crc.cat-bits.64
+ * Initial value: 0xFFFFFFFFFFFFFFFF
+ * Poly: 0x42F0E1EBA9EA3693
+ * Reverse: no
+ * Output xor: 0xFFFFFFFFFFFFFFFF
+ * Check: 0x62EC59E3F1A4F00A
+ */
+class DataTypeSignatureCRC
+{
+    uint64_t crc_;
+
+public:
+    DataTypeSignatureCRC() : crc_(0xFFFFFFFFFFFFFFFF) { }
+
+    void add(uint8_t byte)
+    {
+        static const uint64_t Poly = 0x42F0E1EBA9EA3693;
+        crc_ ^= uint64_t(byte) << 56;
+        for (int i = 0; i < 8; i++)
+            crc_ = (crc_ & (uint64_t(1) << 63)) ? (crc_ << 1) ^ Poly : crc_ << 1;
+    }
+
+    void add(const uint8_t* bytes, unsigned int len)
+    {
+        assert(bytes);
+        while (len--)
+            add(*bytes++);
+    }
+
+    uint64_t get() const { return crc_ ^ 0xFFFFFFFFFFFFFFFF; }
+};
+
 
 struct DataTypeHash
 {

libuavcan/test/data_type.cpp

@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2014 Pavel Kirienko <pavel.kirienko@gmail.com>
+ */
+
+#include <gtest/gtest.h>
+#include <uavcan/internal/data_type.hpp>
+
+
+TEST(DataTypeSignatureCRC, Correctness)
+{
+    uavcan::DataTypeSignatureCRC crc;
+
+    ASSERT_EQ(0xFFFFFFFFFFFFFFFF ^ 0xFFFFFFFFFFFFFFFF, crc.get());
+
+    crc.add('1');
+    crc.add('2');
+    crc.add('3');
+    crc.add(reinterpret_cast<const uint8_t*>("456789"), 6);
+
+    ASSERT_EQ(0x62EC59E3F1A4F00A, crc.get());
+}