-rw-r--r-- 1926 libmceliece-20240726/crypto_kem/6688128/avx/vec128.c raw
// 20240508 djb: include vec128_gf.h
// 20221230 djb: add linker line
// linker define vec128_mul_GF
// linker use vec128_mul_asm
#include "vec128_gf.h"
/* input: v, an element in GF(2^m)[y]/(y^128+y^7+y^2+y+1) in bitsliced form */
/* input: a, an element in GF(2^m)[y]/(y^128+y^7+y^2+y+1) as an array of coefficients */
/* output: out, the product of v and a in bitsliced form */
void vec128_mul_GF(vec128 out[ GFBITS ], vec128 v[ GFBITS ], gf a[ SYS_T ])
{
int i, j;
uint64_t buf[GFBITS][4];
vec128 prod[GFBITS];
uint64_t p[GFBITS];
// polynomial multiplication
for (i = 0; i < GFBITS; i++)
{
buf[i][0] = 0;
buf[i][1] = 0;
buf[i][2] = 0;
buf[i][3] = 0;
}
for (i = SYS_T-1; i >= 0; i--)
{
for (j = 0; j < GFBITS; j++)
{
buf[j][3] <<= 1;
buf[j][3] |= buf[j][2] >> 63;
buf[j][2] <<= 1;
buf[j][2] |= buf[j][1] >> 63;
buf[j][1] <<= 1;
buf[j][1] |= buf[j][0] >> 63;
buf[j][0] <<= 1;
}
vec128_mul_gf(prod, v, a[i]);
for (j = 0; j < GFBITS; j++)
{
buf[j][0] ^= vec128_extract(prod[j], 0);
buf[j][1] ^= vec128_extract(prod[j], 1);
}
}
// reduction modulo y^128+y^7+y^2+y+1
for (i = 0; i < GFBITS; i++)
{
p[i] = buf[i][3];
buf[i][2] ^= p[i] >> (SYS_T - 7 - 64);
buf[i][1] ^= p[i] << (64 - (SYS_T - 7 - 64));
buf[i][2] ^= p[i] >> (SYS_T - 2 - 64);
buf[i][1] ^= p[i] << (64 - (SYS_T - 2 - 64));
buf[i][2] ^= p[i] >> (SYS_T - 1 - 64);
buf[i][1] ^= p[i] << (64 - (SYS_T - 1 - 64));
buf[i][1] ^= p[i];
}
//
for (i = 0; i < GFBITS; i++)
{
p[i] = buf[i][2];
buf[i][1] ^= p[i] >> (SYS_T - 7 - 64);
buf[i][0] ^= p[i] << (64 - (SYS_T - 7 - 64));
buf[i][1] ^= p[i] >> (SYS_T - 2 - 64);
buf[i][0] ^= p[i] << (64 - (SYS_T - 2 - 64));
buf[i][1] ^= p[i] >> (SYS_T - 1 - 64);
buf[i][0] ^= p[i] << (64 - (SYS_T - 1 - 64));
buf[i][0] ^= p[i];
}
//
for (i = 0; i < GFBITS; i++)
out[i] = vec128_set2x(buf[i][0], buf[i][1]);
}