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bertos/algo/crc_ccitt.h

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+/**
+ * \file
+ * <!--
+ * This file is part of BeRTOS.
+ *
+ * Bertos is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * As a special exception, you may use this file as part of a free software
+ * library without restriction.  Specifically, if other files instantiate
+ * templates or use macros or inline functions from this file, or you compile
+ * this file and link it with other files to produce an executable, this
+ * file does not by itself cause the resulting executable to be covered by
+ * the GNU General Public License.  This exception does not however
+ * invalidate any other reasons why the executable file might be covered by
+ * the GNU General Public License.
+ *
+ * Copyright 2009 Develer S.r.l. (http://www.develer.com/)
+ *
+ * -->
+ *
+ * \brief CCITT Cyclic Redundancy Check (CRC-CCITT).
+ *
+ * \note This algorithm is incompatible with the CRC16.
+ *
+ * \author Francesco Sacchi <batt@develer.com>
+ *
+ * $WIZ$ module_name = "crc-ccitt"
+ */
+
+#ifndef ALGO_CRC_CCITT_H
+#define ALGO_CRC_CCITT_H
+
+#include <cfg/compiler.h>
+#include <cpu/pgm.h>
+
+EXTERN_C_BEGIN
+
+/* CRC table */
+extern const uint16_t crc_ccitt_tab[256];
+
+/**
+ * \brief Compute the updated CRC-CCITT value for one octet (inline version)
+ */
+INLINE uint16_t updcrc_ccitt(uint8_t c, uint16_t oldcrc)
+{
+	return (oldcrc >> 8) ^ pgm_read16(&crc_ccitt_tab[(oldcrc ^ c) & 0xff]);
+}
+
+/** CRC-CCITT init value */
+#define CRC_CCITT_INIT_VAL ((uint16_t)0xFFFF)
+
+
+/**
+ * This function implements the CRC-CCITT calculation on a buffer.
+ *
+ * \param crc  Current CRC-CCITT value.
+ * \param buf  The buffer to perform CRC calculation on.
+ * \param len  The length of the Buffer.
+ *
+ * \return The updated CRC-CCITT value.
+ */
+extern uint16_t crc_ccitt(uint16_t crc, const void *buf, size_t len);
+
+EXTERN_C_END
+
+#endif /* ALGO_CRC_CCITT_H */