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