Resolve "Add MACsec support"

include/icsneo/communication/crc32.h

@@ -0,0 +1,27 @@
+/*
+ * crc32.h
+ *
+ *  Created on: Jun 22, 2020
+ *      Author: BJones
+ */
+
+#pragma once
+
+#ifndef CRC32_H_
+#define CRC32_H_
+
+#include <stdint.h>
+
+/*
+ * When any data/buffer is run through calCRC(), then the resulting CRC value
+ *  is appended to the end of the data/buffer and the data/buffer is rerun
+ *  through calCRC(), the result will be CRC32_IDENT
+ */
+#define CRC32_IDENT (0x2144DF1C) /**< CRC check value */
+
+#define CRC32_ISVALID(crc) ((crc) == CRC32_IDENT)
+
+uint32_t crc32(uint32_t crc, const unsigned char* buf, uint32_t len);
+uint32_t revcrc32(uint32_t crc, const unsigned char* buf, uint32_t len);
+
+#endif // CRC32_H_