Initial revision

1 files changed, 40 insertions, 0 deletions

diff --git a/crc.h b/crc.h
new file mode 100644
index 00000000..3ba13236
--- /dev/null
+++ b/crc.h
@@ -0,0 +1,40 @@
+#ifndef CRYPTOPP_CRC32_H
+#define CRYPTOPP_CRC32_H
+
+#include "cryptlib.h"
+
+NAMESPACE_BEGIN(CryptoPP)
+
+const word32 CRC32_NEGL = 0xffffffffL;
+
+#ifdef IS_LITTLE_ENDIAN
+#define CRC32_INDEX(c) (c & 0xff)
+#define CRC32_SHIFTED(c) (c >> 8)
+#else
+#define CRC32_INDEX(c) (c >> 24)
+#define CRC32_SHIFTED(c) (c << 8)
+#endif
+
+//! CRC Checksum Calculation
+class CRC32 : public HashTransformation
+{
+public:
+	enum {DIGESTSIZE = 4};
+	CRC32();
+	void Update(const byte *input, unsigned int length);
+	void TruncatedFinal(byte *hash, unsigned int size);
+	unsigned int DigestSize() const {return DIGESTSIZE;}
+
+	void UpdateByte(byte b) {m_crc = m_tab[CRC32_INDEX(m_crc) ^ b] ^ CRC32_SHIFTED(m_crc);}
+	byte GetCrcByte(unsigned int i) const {return ((byte *)&(m_crc))[i];}
+
+private:
+	void Reset() {m_crc = CRC32_NEGL;}
+	
+	static const word32 m_tab[256];
+	word32 m_crc;
+};
+
+NAMESPACE_END
+
+#endif