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