202 lines
9.2 KiB
C
202 lines
9.2 KiB
C
#ifndef INCLUDED_OP25_HAMMING_H
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#define INCLUDED_OP25_HAMMING_H
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#include <cstddef>
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#include <stdint.h>
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#include <assert.h>
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/*
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* APCO Hamming(15,11,3) ecoder.
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*
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* \param val The 11-bit value to encode.
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* \return The encoded codeword.
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*/
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static inline uint16_t
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hamming_15_encode(uint16_t code_word_in)
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{
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static long int encoding[11] = {
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0x400f, 0x200e, 0x100d, 0x080c, 0x040b, 0x020a, 0x0109,
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0x0087, 0x0046, 0x0025, 0x0013
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};
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uint16_t code_word_out = 0u;
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for(uint8_t i = 0; i < 11; ++i) {
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if(code_word_in & (1u << (10 - i))) {
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code_word_out ^= encoding[i];
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}
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}
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return code_word_out;
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}
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/*
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* APCO Hamming(15,11,3) decoder.
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*
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* \param cw The 15-bit codeword to decode.
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* \return The number of errors detected.
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*/
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static inline size_t
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hamming_15_decode(uint16_t& cw)
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{
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static const int encoding[2048] = {
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0, 3, 5, 6, 6, 5, 3, 0, 7, 4, 2, 1, 1, 2, 4, 7,
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9, 10, 12, 15, 15, 12, 10, 9, 14, 13, 11, 8, 8, 11, 13, 14,
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10, 9, 15, 12, 12, 15, 9, 10, 13, 14, 8, 11, 11, 8, 14, 13,
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3, 0, 6, 5, 5, 6, 0, 3, 4, 7, 1, 2, 2, 1, 7, 4,
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11, 8, 14, 13, 13, 14, 8, 11, 12, 15, 9, 10, 10, 9, 15, 12,
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2, 1, 7, 4, 4, 7, 1, 2, 5, 6, 0, 3, 3, 0, 6, 5,
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1, 2, 4, 7, 7, 4, 2, 1, 6, 5, 3, 0, 0, 3, 5, 6,
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8, 11, 13, 14, 14, 13, 11, 8, 15, 12, 10, 9, 9, 10, 12, 15,
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12, 15, 9, 10, 10, 9, 15, 12, 11, 8, 14, 13, 13, 14, 8, 11,
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5, 6, 0, 3, 3, 0, 6, 5, 2, 1, 7, 4, 4, 7, 1, 2,
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6, 5, 3, 0, 0, 3, 5, 6, 1, 2, 4, 7, 7, 4, 2, 1,
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15, 12, 10, 9, 9, 10, 12, 15, 8, 11, 13, 14, 14, 13, 11, 8,
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7, 4, 2, 1, 1, 2, 4, 7, 0, 3, 5, 6, 6, 5, 3, 0,
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14, 13, 11, 8, 8, 11, 13, 14, 9, 10, 12, 15, 15, 12, 10, 9,
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13, 14, 8, 11, 11, 8, 14, 13, 10, 9, 15, 12, 12, 15, 9, 10,
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4, 7, 1, 2, 2, 1, 7, 4, 3, 0, 6, 5, 5, 6, 0, 3,
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13, 14, 8, 11, 11, 8, 14, 13, 10, 9, 15, 12, 12, 15, 9, 10,
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4, 7, 1, 2, 2, 1, 7, 4, 3, 0, 6, 5, 5, 6, 0, 3,
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7, 4, 2, 1, 1, 2, 4, 7, 0, 3, 5, 6, 6, 5, 3, 0,
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14, 13, 11, 8, 8, 11, 13, 14, 9, 10, 12, 15, 15, 12, 10, 9,
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6, 5, 3, 0, 0, 3, 5, 6, 1, 2, 4, 7, 7, 4, 2, 1,
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15, 12, 10, 9, 9, 10, 12, 15, 8, 11, 13, 14, 14, 13, 11, 8,
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12, 15, 9, 10, 10, 9, 15, 12, 11, 8, 14, 13, 13, 14, 8, 11,
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5, 6, 0, 3, 3, 0, 6, 5, 2, 1, 7, 4, 4, 7, 1, 2,
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1, 2, 4, 7, 7, 4, 2, 1, 6, 5, 3, 0, 0, 3, 5, 6,
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8, 11, 13, 14, 14, 13, 11, 8, 15, 12, 10, 9, 9, 10, 12, 15,
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11, 8, 14, 13, 13, 14, 8, 11, 12, 15, 9, 10, 10, 9, 15, 12,
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2, 1, 7, 4, 4, 7, 1, 2, 5, 6, 0, 3, 3, 0, 6, 5,
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10, 9, 15, 12, 12, 15, 9, 10, 13, 14, 8, 11, 11, 8, 14, 13,
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3, 0, 6, 5, 5, 6, 0, 3, 4, 7, 1, 2, 2, 1, 7, 4,
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0, 3, 5, 6, 6, 5, 3, 0, 7, 4, 2, 1, 1, 2, 4, 7,
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9, 10, 12, 15, 15, 12, 10, 9, 14, 13, 11, 8, 8, 11, 13, 14,
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14, 13, 11, 8, 8, 11, 13, 14, 9, 10, 12, 15, 15, 12, 10, 9,
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7, 4, 2, 1, 1, 2, 4, 7, 0, 3, 5, 6, 6, 5, 3, 0,
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4, 7, 1, 2, 2, 1, 7, 4, 3, 0, 6, 5, 5, 6, 0, 3,
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13, 14, 8, 11, 11, 8, 14, 13, 10, 9, 15, 12, 12, 15, 9, 10,
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5, 6, 0, 3, 3, 0, 6, 5, 2, 1, 7, 4, 4, 7, 1, 2,
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12, 15, 9, 10, 10, 9, 15, 12, 11, 8, 14, 13, 13, 14, 8, 11,
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15, 12, 10, 9, 9, 10, 12, 15, 8, 11, 13, 14, 14, 13, 11, 8,
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6, 5, 3, 0, 0, 3, 5, 6, 1, 2, 4, 7, 7, 4, 2, 1,
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2, 1, 7, 4, 4, 7, 1, 2, 5, 6, 0, 3, 3, 0, 6, 5,
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11, 8, 14, 13, 13, 14, 8, 11, 12, 15, 9, 10, 10, 9, 15, 12,
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8, 11, 13, 14, 14, 13, 11, 8, 15, 12, 10, 9, 9, 10, 12, 15,
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1, 2, 4, 7, 7, 4, 2, 1, 6, 5, 3, 0, 0, 3, 5, 6,
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9, 10, 12, 15, 15, 12, 10, 9, 14, 13, 11, 8, 8, 11, 13, 14,
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0, 3, 5, 6, 6, 5, 3, 0, 7, 4, 2, 1, 1, 2, 4, 7,
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3, 0, 6, 5, 5, 6, 0, 3, 4, 7, 1, 2, 2, 1, 7, 4,
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10, 9, 15, 12, 12, 15, 9, 10, 13, 14, 8, 11, 11, 8, 14, 13,
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3, 0, 6, 5, 5, 6, 0, 3, 4, 7, 1, 2, 2, 1, 7, 4,
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10, 9, 15, 12, 12, 15, 9, 10, 13, 14, 8, 11, 11, 8, 14, 13,
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9, 10, 12, 15, 15, 12, 10, 9, 14, 13, 11, 8, 8, 11, 13, 14,
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0, 3, 5, 6, 6, 5, 3, 0, 7, 4, 2, 1, 1, 2, 4, 7,
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8, 11, 13, 14, 14, 13, 11, 8, 15, 12, 10, 9, 9, 10, 12, 15,
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1, 2, 4, 7, 7, 4, 2, 1, 6, 5, 3, 0, 0, 3, 5, 6,
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2, 1, 7, 4, 4, 7, 1, 2, 5, 6, 0, 3, 3, 0, 6, 5,
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11, 8, 14, 13, 13, 14, 8, 11, 12, 15, 9, 10, 10, 9, 15, 12,
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15, 12, 10, 9, 9, 10, 12, 15, 8, 11, 13, 14, 14, 13, 11, 8,
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6, 5, 3, 0, 0, 3, 5, 6, 1, 2, 4, 7, 7, 4, 2, 1,
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5, 6, 0, 3, 3, 0, 6, 5, 2, 1, 7, 4, 4, 7, 1, 2,
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12, 15, 9, 10, 10, 9, 15, 12, 11, 8, 14, 13, 13, 14, 8, 11,
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4, 7, 1, 2, 2, 1, 7, 4, 3, 0, 6, 5, 5, 6, 0, 3,
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13, 14, 8, 11, 11, 8, 14, 13, 10, 9, 15, 12, 12, 15, 9, 10,
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14, 13, 11, 8, 8, 11, 13, 14, 9, 10, 12, 15, 15, 12, 10, 9,
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7, 4, 2, 1, 1, 2, 4, 7, 0, 3, 5, 6, 6, 5, 3, 0,
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15, 12, 10, 9, 9, 10, 12, 15, 8, 11, 13, 14, 14, 13, 11, 8,
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6, 5, 3, 0, 0, 3, 5, 6, 1, 2, 4, 7, 7, 4, 2, 1,
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5, 6, 0, 3, 3, 0, 6, 5, 2, 1, 7, 4, 4, 7, 1, 2,
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12, 15, 9, 10, 10, 9, 15, 12, 11, 8, 14, 13, 13, 14, 8, 11,
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4, 7, 1, 2, 2, 1, 7, 4, 3, 0, 6, 5, 5, 6, 0, 3,
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13, 14, 8, 11, 11, 8, 14, 13, 10, 9, 15, 12, 12, 15, 9, 10,
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14, 13, 11, 8, 8, 11, 13, 14, 9, 10, 12, 15, 15, 12, 10, 9,
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7, 4, 2, 1, 1, 2, 4, 7, 0, 3, 5, 6, 6, 5, 3, 0,
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3, 0, 6, 5, 5, 6, 0, 3, 4, 7, 1, 2, 2, 1, 7, 4,
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10, 9, 15, 12, 12, 15, 9, 10, 13, 14, 8, 11, 11, 8, 14, 13,
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9, 10, 12, 15, 15, 12, 10, 9, 14, 13, 11, 8, 8, 11, 13, 14,
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0, 3, 5, 6, 6, 5, 3, 0, 7, 4, 2, 1, 1, 2, 4, 7,
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8, 11, 13, 14, 14, 13, 11, 8, 15, 12, 10, 9, 9, 10, 12, 15,
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1, 2, 4, 7, 7, 4, 2, 1, 6, 5, 3, 0, 0, 3, 5, 6,
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2, 1, 7, 4, 4, 7, 1, 2, 5, 6, 0, 3, 3, 0, 6, 5,
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11, 8, 14, 13, 13, 14, 8, 11, 12, 15, 9, 10, 10, 9, 15, 12,
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2, 1, 7, 4, 4, 7, 1, 2, 5, 6, 0, 3, 3, 0, 6, 5,
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11, 8, 14, 13, 13, 14, 8, 11, 12, 15, 9, 10, 10, 9, 15, 12,
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8, 11, 13, 14, 14, 13, 11, 8, 15, 12, 10, 9, 9, 10, 12, 15,
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1, 2, 4, 7, 7, 4, 2, 1, 6, 5, 3, 0, 0, 3, 5, 6,
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9, 10, 12, 15, 15, 12, 10, 9, 14, 13, 11, 8, 8, 11, 13, 14,
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0, 3, 5, 6, 6, 5, 3, 0, 7, 4, 2, 1, 1, 2, 4, 7,
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3, 0, 6, 5, 5, 6, 0, 3, 4, 7, 1, 2, 2, 1, 7, 4,
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10, 9, 15, 12, 12, 15, 9, 10, 13, 14, 8, 11, 11, 8, 14, 13,
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14, 13, 11, 8, 8, 11, 13, 14, 9, 10, 12, 15, 15, 12, 10, 9,
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7, 4, 2, 1, 1, 2, 4, 7, 0, 3, 5, 6, 6, 5, 3, 0,
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4, 7, 1, 2, 2, 1, 7, 4, 3, 0, 6, 5, 5, 6, 0, 3,
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13, 14, 8, 11, 11, 8, 14, 13, 10, 9, 15, 12, 12, 15, 9, 10,
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5, 6, 0, 3, 3, 0, 6, 5, 2, 1, 7, 4, 4, 7, 1, 2,
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12, 15, 9, 10, 10, 9, 15, 12, 11, 8, 14, 13, 13, 14, 8, 11,
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15, 12, 10, 9, 9, 10, 12, 15, 8, 11, 13, 14, 14, 13, 11, 8,
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6, 5, 3, 0, 0, 3, 5, 6, 1, 2, 4, 7, 7, 4, 2, 1,
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1, 2, 4, 7, 7, 4, 2, 1, 6, 5, 3, 0, 0, 3, 5, 6,
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8, 11, 13, 14, 14, 13, 11, 8, 15, 12, 10, 9, 9, 10, 12, 15,
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11, 8, 14, 13, 13, 14, 8, 11, 12, 15, 9, 10, 10, 9, 15, 12,
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2, 1, 7, 4, 4, 7, 1, 2, 5, 6, 0, 3, 3, 0, 6, 5,
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10, 9, 15, 12, 12, 15, 9, 10, 13, 14, 8, 11, 11, 8, 14, 13,
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3, 0, 6, 5, 5, 6, 0, 3, 4, 7, 1, 2, 2, 1, 7, 4,
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0, 3, 5, 6, 6, 5, 3, 0, 7, 4, 2, 1, 1, 2, 4, 7,
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9, 10, 12, 15, 15, 12, 10, 9, 14, 13, 11, 8, 8, 11, 13, 14,
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13, 14, 8, 11, 11, 8, 14, 13, 10, 9, 15, 12, 12, 15, 9, 10,
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4, 7, 1, 2, 2, 1, 7, 4, 3, 0, 6, 5, 5, 6, 0, 3,
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7, 4, 2, 1, 1, 2, 4, 7, 0, 3, 5, 6, 6, 5, 3, 0,
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14, 13, 11, 8, 8, 11, 13, 14, 9, 10, 12, 15, 15, 12, 10, 9,
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6, 5, 3, 0, 0, 3, 5, 6, 1, 2, 4, 7, 7, 4, 2, 1,
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15, 12, 10, 9, 9, 10, 12, 15, 8, 11, 13, 14, 14, 13, 11, 8,
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12, 15, 9, 10, 10, 9, 15, 12, 11, 8, 14, 13, 13, 14, 8, 11,
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5, 6, 0, 3, 3, 0, 6, 5, 2, 1, 7, 4, 4, 7, 1, 2,
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12, 15, 9, 10, 10, 9, 15, 12, 11, 8, 14, 13, 13, 14, 8, 11,
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5, 6, 0, 3, 3, 0, 6, 5, 2, 1, 7, 4, 4, 7, 1, 2,
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6, 5, 3, 0, 0, 3, 5, 6, 1, 2, 4, 7, 7, 4, 2, 1,
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15, 12, 10, 9, 9, 10, 12, 15, 8, 11, 13, 14, 14, 13, 11, 8,
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7, 4, 2, 1, 1, 2, 4, 7, 0, 3, 5, 6, 6, 5, 3, 0,
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14, 13, 11, 8, 8, 11, 13, 14, 9, 10, 12, 15, 15, 12, 10, 9,
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13, 14, 8, 11, 11, 8, 14, 13, 10, 9, 15, 12, 12, 15, 9, 10,
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4, 7, 1, 2, 2, 1, 7, 4, 3, 0, 6, 5, 5, 6, 0, 3,
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0, 3, 5, 6, 6, 5, 3, 0, 7, 4, 2, 1, 1, 2, 4, 7,
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9, 10, 12, 15, 15, 12, 10, 9, 14, 13, 11, 8, 8, 11, 13, 14,
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10, 9, 15, 12, 12, 15, 9, 10, 13, 14, 8, 11, 11, 8, 14, 13,
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3, 0, 6, 5, 5, 6, 0, 3, 4, 7, 1, 2, 2, 1, 7, 4,
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11, 8, 14, 13, 13, 14, 8, 11, 12, 15, 9, 10, 10, 9, 15, 12,
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2, 1, 7, 4, 4, 7, 1, 2, 5, 6, 0, 3, 3, 0, 6, 5,
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1, 2, 4, 7, 7, 4, 2, 1, 6, 5, 3, 0, 0, 3, 5, 6,
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8, 11, 13, 14, 14, 13, 11, 8, 15, 12, 10, 9, 9, 10, 12, 15
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};
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static const int decoding[16] = {
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0, 0, 0, 1, 0, 2, 4, 8, 0, 16, 32, 64, 128, 256, 512, 1024
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};
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size_t errs = 0;
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uint16_t par = cw & 0xf;
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cw &= 0xffff;
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cw >>= 4;
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uint16_t correction = decoding[encoding[cw] ^ par];
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if(correction) {
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cw ^= correction;
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++errs;
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}
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return errs;
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}
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static const uint32_t hmg1063EncTbl[64] = {
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0, 12, 3, 15, 7, 11, 4, 8, 11, 7, 8, 4, 12, 0, 15, 3,
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13, 1, 14, 2, 10, 6, 9, 5, 6, 10, 5, 9, 1, 13, 2, 14,
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14, 2, 13, 1, 9, 5, 10, 6, 5, 9, 6, 10, 2, 14, 1, 13,
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3, 15, 0, 12, 4, 8, 7, 11, 8, 4, 11, 7, 15, 3, 12, 0 };
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static const uint32_t hmg1063DecTbl[16] = {
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0, 0, 0, 2, 0, 0, 0, 4, 0, 0, 0, 8, 1, 16, 32, 0 };
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static inline int hmg1063Dec (uint32_t Dat, uint32_t Par) {
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assert ((Dat < 64) && (Par < 16));
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return Dat ^ hmg1063DecTbl[hmg1063EncTbl[Dat] ^ Par];
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}
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#endif /* INCLUDED_OP25_HAMMING_H */
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