-rw-r--r-- 3869 libmceliece-20240726/crypto_kem/8192128/avx/gf.c raw
/*
this file is for functions for field arithmetic
*/
// 20221231 djb: const for GF_mul
// 20221230 djb: add linker line
// linker define gf_iszero gf_mul gf_inv gf_frac GF_mul
#include "gf.h"
#include "params.h"
#include <stdio.h>
/* field multiplication */
gf gf_mul(gf in0, gf in1)
{
int i;
uint64_t tmp;
uint64_t t0;
uint64_t t1;
uint64_t t;
t0 = in0;
t1 = in1;
tmp = t0 * (t1 & 1);
for (i = 1; i < GFBITS; i++)
tmp ^= (t0 * (t1 & (1 << i)));
//
t = tmp & 0x1FF0000;
tmp ^= (t >> 9) ^ (t >> 10) ^ (t >> 12) ^ (t >> 13);
t = tmp & 0x000E000;
tmp ^= (t >> 9) ^ (t >> 10) ^ (t >> 12) ^ (t >> 13);
return tmp & GFMASK;
}
/* 2 field squarings */
static inline gf gf_sq2(gf in)
{
int i;
const uint64_t B[] = {0x1111111111111111,
0x0303030303030303,
0x000F000F000F000F,
0x000000FF000000FF};
const uint64_t M[] = {0x0001FF0000000000,
0x000000FF80000000,
0x000000007FC00000,
0x00000000003FE000};
uint64_t x = in;
uint64_t t;
x = (x | (x << 24)) & B[3];
x = (x | (x << 12)) & B[2];
x = (x | (x << 6)) & B[1];
x = (x | (x << 3)) & B[0];
for (i = 0; i < 4; i++)
{
t = x & M[i];
x ^= (t >> 9) ^ (t >> 10) ^ (t >> 12) ^ (t >> 13);
}
return x & GFMASK;
}
/* square and multiply */
static inline gf gf_sqmul(gf in, gf m)
{
int i;
uint64_t x;
uint64_t t0;
uint64_t t1;
uint64_t t;
const uint64_t M[] = {0x0000001FF0000000,
0x000000000FF80000,
0x000000000007E000};
t0 = in;
t1 = m;
x = (t1 << 6) * (t0 & (1 << 6));
t0 ^= (t0 << 7);
x ^= (t1 * (t0 & (0x04001)));
x ^= (t1 * (t0 & (0x08002))) << 1;
x ^= (t1 * (t0 & (0x10004))) << 2;
x ^= (t1 * (t0 & (0x20008))) << 3;
x ^= (t1 * (t0 & (0x40010))) << 4;
x ^= (t1 * (t0 & (0x80020))) << 5;
for (i = 0; i < 3; i++)
{
t = x & M[i];
x ^= (t >> 9) ^ (t >> 10) ^ (t >> 12) ^ (t >> 13);
}
return x & GFMASK;
}
/* square twice and multiply */
static inline gf gf_sq2mul(gf in, gf m)
{
int i;
uint64_t x;
uint64_t t0;
uint64_t t1;
uint64_t t;
const uint64_t M[] = {0x1FF0000000000000,
0x000FF80000000000,
0x000007FC00000000,
0x00000003FE000000,
0x0000000001FE0000,
0x000000000001E000};
t0 = in;
t1 = m;
x = (t1 << 18) * (t0 & (1 << 6));
t0 ^= (t0 << 21);
x ^= (t1 * (t0 & (0x010000001)));
x ^= (t1 * (t0 & (0x020000002))) << 3;
x ^= (t1 * (t0 & (0x040000004))) << 6;
x ^= (t1 * (t0 & (0x080000008))) << 9;
x ^= (t1 * (t0 & (0x100000010))) << 12;
x ^= (t1 * (t0 & (0x200000020))) << 15;
for (i = 0; i < 6; i++)
{
t = x & M[i];
x ^= (t >> 9) ^ (t >> 10) ^ (t >> 12) ^ (t >> 13);
}
return x & GFMASK;
}
/* return num/den */
gf gf_frac(gf den, gf num)
{
gf tmp_11;
gf tmp_1111;
gf out;
tmp_11 = gf_sqmul(den, den); // 11
tmp_1111 = gf_sq2mul(tmp_11, tmp_11); // 1111
out = gf_sq2(tmp_1111);
out = gf_sq2mul(out, tmp_1111); // 11111111
out = gf_sq2(out);
out = gf_sq2mul(out, tmp_1111); // 111111111111
return gf_sqmul(out, num); // 1111111111110
}
/* return 1/den */
gf gf_inv(gf den)
{
return gf_frac(den, ((gf) 1));
}
/* check if a == 0 */
gf gf_iszero(gf a)
{
uint32_t t = a;
t -= 1;
t >>= 19;
return (gf) t;
}
/* multiplication in GF((2^m)^t) */
void GF_mul(gf *out, const gf *in0, const gf *in1)
{
int i, j;
gf prod[255];
for (i = 0; i < 255; i++)
prod[i] = 0;
for (i = 0; i < 128; i++)
for (j = 0; j < 128; j++)
prod[i+j] ^= gf_mul(in0[i], in1[j]);
//
for (i = 254; i >= 128; i--)
{
prod[i - 123] ^= gf_mul(prod[i], (gf) 7682);
prod[i - 125] ^= gf_mul(prod[i], (gf) 2159);
prod[i - 128] ^= gf_mul(prod[i], (gf) 3597);
}
for (i = 0; i < 128; i++)
out[i] = prod[i];
}