mirror of
https://github.com/henrydcase/pqc.git
synced 2024-11-27 09:51:30 +00:00
43 lines
1.2 KiB
C
43 lines
1.2 KiB
C
#include "parameters.h"
|
|
#include "repetition.h"
|
|
#include <immintrin.h>
|
|
#include <stddef.h>
|
|
#include <stdint.h>
|
|
#include <stdio.h>
|
|
/**
|
|
* @file repetition.c
|
|
* @brief Implementation of repetition codes
|
|
*/
|
|
|
|
|
|
|
|
/**
|
|
* @brief Decoding the code words to a message using the repetition code
|
|
*
|
|
* We use a majority decoding. In fact we have that PARAM_N2 = 2 * PARAM_T + 1, thus,
|
|
* if the Hamming weight of the vector is greater than PARAM_T, the code word is decoded
|
|
* to 1 and 0 otherwise.
|
|
*
|
|
* @param[out] m Pointer to an array that is the message
|
|
* @param[in] em Pointer to an array that is the code word
|
|
*/
|
|
void PQCLEAN_HQC256_AVX2_repetition_code_decode(uint64_t *m, const uint64_t *em) {
|
|
size_t t = 0, b, bn, bi, c, cn, ci;
|
|
uint64_t cx, ones;
|
|
uint64_t cy;
|
|
|
|
for (b = 0; b < PARAM_N1N2 - PARAM_N2 + 1; b += PARAM_N2) {
|
|
bn = b >> 6;
|
|
bi = b & 63;
|
|
c = b + PARAM_N2 - 1;
|
|
cn = c >> 6;
|
|
ci = c & 63;
|
|
cx = em[cn] << (63 - ci);
|
|
int64_t verif = (cn == (bn + 1));
|
|
cy = em[bn + 1];
|
|
ones = _mm_popcnt_u64((em[bn] >> bi) | (cx * (1 - verif))) + _mm_popcnt_u64((1 - verif) * cy + verif * cx);
|
|
m[t >> 6] |= ((uint64_t)(ones > PARAM_T)) << (t & 63);
|
|
t++;
|
|
}
|
|
}
|