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+/*
+Hamming Error-Correcting Code (ECC)
+Optimized for avr-gcc 4.8.1 in Atmel AVR Studio 6.2
+August 12, 2014
+
+You should include Hamming.c, Hamming.h, and only one of the other Hamming files in your project.
+The other Hamming files implement the same methods in different ways, that may be better or worse for your needs.
+
+This was created for LoFi in the TheHackadayPrize contest.
+http://hackaday.io/project/1552-LoFi
+
+Copyright 2014 David Cook
+RobotRoom.com
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+#ifndef _HAMMING_H
+#define _HAMMING_H
+
+#ifndef _AVR_H
+typedef unsigned char byte;
+typedef unsigned char nibble;
+#endif
+
+/**** These are needed to transmit and receive ****/
+
+// Given a byte to transmit, this returns the parity as a nibble
+nibble HammingCalculateParity128(byte value);
+
+// Given two bytes to transmit, this returns the parity
+// as a byte with the lower nibble being for the first byte,
+// and the upper nibble being for the second byte.
+byte HammingCalculateParity2416(byte first, byte second);
+
+
+
+/**** These are needed only to receive ****/
+
+// Given a pointer to a received byte and the received parity (as a lower nibble),
+// this calculates what the parity should be and fixes the received value if needed.
+// It returns the number of bits corrected:
+// 0 means no errors
+// 1 means one corrected error
+// 3 means corrections not possible
+byte HammingCorrect128(byte* value, nibble parity);
+
+// Given a pointer to a first value and a pointer to a second value and
+// their combined given parity (lower nibble first parity, upper nibble second parity),
+// this calculates what the parity should be and fixes the values if needed.
+// It returns the number of bits corrected:
+// 0 means no errors
+// 1 means one corrected error
+// 2 means two corrected errors
+// 3 means corrections not possible
+byte HammingCorrect2416(byte* first, byte* second, byte parity);
+
+#endif // _HAMMING_H