pqc/external/flint-2.4.3/fmpz_mat/mul_multi_mod.c
2014-05-24 23:16:06 +02:00

141 lines
3.9 KiB
C

/*=============================================================================
This file is part of FLINT.
FLINT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FLINT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with FLINT; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2010 Fredrik Johansson
******************************************************************************/
#include "fmpz_mat.h"
void
_fmpz_mat_mul_multi_mod(fmpz_mat_t C, const fmpz_mat_t A, const fmpz_mat_t B,
mp_bitcnt_t bits)
{
slong i, j;
fmpz_comb_t comb;
fmpz_comb_temp_t comb_temp;
slong num_primes;
mp_bitcnt_t primes_bits;
mp_limb_t * primes;
mp_limb_t * residues;
nmod_mat_t * mod_C;
nmod_mat_t * mod_A;
nmod_mat_t * mod_B;
primes_bits = NMOD_MAT_OPTIMAL_MODULUS_BITS;
if (bits < primes_bits)
{
primes_bits = bits;
num_primes = 1;
}
else
{
/* Round up in the division */
num_primes = (bits + primes_bits - 1) / primes_bits;
}
/* Initialize */
primes = flint_malloc(sizeof(mp_limb_t) * num_primes);
primes[0] = n_nextprime(UWORD(1) << primes_bits, 0);
for (i = 1; i < num_primes; i++)
primes[i] = n_nextprime(primes[i-1], 0);
residues = flint_malloc(sizeof(mp_limb_t) * num_primes);
mod_A = flint_malloc(sizeof(nmod_mat_t) * num_primes);
mod_B = flint_malloc(sizeof(nmod_mat_t) * num_primes);
mod_C = flint_malloc(sizeof(nmod_mat_t) * num_primes);
for (i = 0; i < num_primes; i++)
{
nmod_mat_init(mod_A[i], A->r, A->c, primes[i]);
nmod_mat_init(mod_B[i], B->r, B->c, primes[i]);
nmod_mat_init(mod_C[i], C->r, C->c, primes[i]);
}
fmpz_comb_init(comb, primes, num_primes);
fmpz_comb_temp_init(comb_temp, comb);
/* Calculate residues of A */
for (i = 0; i < A->r * A->c; i++)
{
fmpz_multi_mod_ui(residues, &A->entries[i], comb, comb_temp);
for (j = 0; j < num_primes; j++)
mod_A[j]->entries[i] = residues[j];
}
/* Calculate residues of B */
for (i = 0; i < B->r * B->c; i++)
{
fmpz_multi_mod_ui(residues, &B->entries[i], comb, comb_temp);
for (j = 0; j < num_primes; j++)
mod_B[j]->entries[i] = residues[j];
}
/* Multiply */
for (i = 0; i < num_primes; i++)
{
nmod_mat_mul(mod_C[i], mod_A[i], mod_B[i]);
}
/* Chinese remaindering */
for (i = 0; i < C->r * C->c; i++)
{
for (j = 0; j < num_primes; j++)
residues[j] = mod_C[j]->entries[i];
fmpz_multi_CRT_ui(&C->entries[i], residues, comb, comb_temp, 1);
}
/* Cleanup */
for (i = 0; i < num_primes; i++)
{
nmod_mat_clear(mod_A[i]);
nmod_mat_clear(mod_B[i]);
nmod_mat_clear(mod_C[i]);
}
flint_free(mod_A);
flint_free(mod_B);
flint_free(mod_C);
fmpz_comb_temp_clear(comb_temp);
fmpz_comb_clear(comb);
flint_free(residues);
flint_free(primes);
}
void
fmpz_mat_mul_multi_mod(fmpz_mat_t C, const fmpz_mat_t A, const fmpz_mat_t B)
{
slong A_bits;
slong B_bits;
A_bits = fmpz_mat_max_bits(A);
B_bits = fmpz_mat_max_bits(B);
_fmpz_mat_mul_multi_mod(C, A, B, FLINT_ABS(A_bits) + FLINT_ABS(B_bits) \
+ FLINT_BIT_COUNT(A->c) + 1);
}