pqc/crypto_kem/mceliece8192128f/clean/synd.c

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/*
This file is for syndrome computation
*/
#include "synd.h"
#include "params.h"
#include "root.h"
/* input: Goppa polynomial f, support L, received word r */
/* output: out, the syndrome of length 2t */
void PQCLEAN_MCELIECE8192128F_CLEAN_synd(gf *out, gf *f, gf *L, const unsigned char *r) {
int i, j;
gf e, e_inv, c;
for (j = 0; j < 2 * SYS_T; j++) {
out[j] = 0;
}
for (i = 0; i < SYS_N; i++) {
c = (r[i / 8] >> (i % 8)) & 1;
e = PQCLEAN_MCELIECE8192128F_CLEAN_eval(f, L[i]);
e_inv = PQCLEAN_MCELIECE8192128F_CLEAN_gf_inv(PQCLEAN_MCELIECE8192128F_CLEAN_gf_mul(e, e));
for (j = 0; j < 2 * SYS_T; j++) {
out[j] = PQCLEAN_MCELIECE8192128F_CLEAN_gf_add(out[j], PQCLEAN_MCELIECE8192128F_CLEAN_gf_mul(e_inv, c));
e_inv = PQCLEAN_MCELIECE8192128F_CLEAN_gf_mul(e_inv, L[i]);
}
}
}