cpython/Modules/_decimal/libmpdec/convolute.c

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/*
* Copyright (c) 2008-2020 Stefan Krah. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include "mpdecimal.h"
#include "bits.h"
#include "constants.h"
#include "convolute.h"
#include "fnt.h"
#include "fourstep.h"
#include "numbertheory.h"
#include "sixstep.h"
#include "umodarith.h"
/* Bignum: Fast convolution using the Number Theoretic Transform. Used for
the multiplication of very large coefficients. */
/* Convolute the data in c1 and c2. Result is in c1. */
int
fnt_convolute(mpd_uint_t *c1, mpd_uint_t *c2, mpd_size_t n, int modnum)
{
int (*fnt)(mpd_uint_t *, mpd_size_t, int);
int (*inv_fnt)(mpd_uint_t *, mpd_size_t, int);
#ifdef PPRO
double dmod;
uint32_t dinvmod[3];
#endif
mpd_uint_t n_inv, umod;
mpd_size_t i;
SETMODULUS(modnum);
n_inv = POWMOD(n, (umod-2));
if (ispower2(n)) {
if (n > SIX_STEP_THRESHOLD) {
fnt = six_step_fnt;
inv_fnt = inv_six_step_fnt;
}
else {
fnt = std_fnt;
inv_fnt = std_inv_fnt;
}
}
else {
fnt = four_step_fnt;
inv_fnt = inv_four_step_fnt;
}
if (!fnt(c1, n, modnum)) {
return 0;
}
if (!fnt(c2, n, modnum)) {
return 0;
}
for (i = 0; i < n-1; i += 2) {
mpd_uint_t x0 = c1[i];
mpd_uint_t y0 = c2[i];
mpd_uint_t x1 = c1[i+1];
mpd_uint_t y1 = c2[i+1];
MULMOD2(&x0, y0, &x1, y1);
c1[i] = x0;
c1[i+1] = x1;
}
if (!inv_fnt(c1, n, modnum)) {
return 0;
}
for (i = 0; i < n-3; i += 4) {
mpd_uint_t x0 = c1[i];
mpd_uint_t x1 = c1[i+1];
mpd_uint_t x2 = c1[i+2];
mpd_uint_t x3 = c1[i+3];
MULMOD2C(&x0, &x1, n_inv);
MULMOD2C(&x2, &x3, n_inv);
c1[i] = x0;
c1[i+1] = x1;
c1[i+2] = x2;
c1[i+3] = x3;
}
return 1;
}
/* Autoconvolute the data in c1. Result is in c1. */
int
fnt_autoconvolute(mpd_uint_t *c1, mpd_size_t n, int modnum)
{
int (*fnt)(mpd_uint_t *, mpd_size_t, int);
int (*inv_fnt)(mpd_uint_t *, mpd_size_t, int);
#ifdef PPRO
double dmod;
uint32_t dinvmod[3];
#endif
mpd_uint_t n_inv, umod;
mpd_size_t i;
SETMODULUS(modnum);
n_inv = POWMOD(n, (umod-2));
if (ispower2(n)) {
if (n > SIX_STEP_THRESHOLD) {
fnt = six_step_fnt;
inv_fnt = inv_six_step_fnt;
}
else {
fnt = std_fnt;
inv_fnt = std_inv_fnt;
}
}
else {
fnt = four_step_fnt;
inv_fnt = inv_four_step_fnt;
}
if (!fnt(c1, n, modnum)) {
return 0;
}
for (i = 0; i < n-1; i += 2) {
mpd_uint_t x0 = c1[i];
mpd_uint_t x1 = c1[i+1];
MULMOD2(&x0, x0, &x1, x1);
c1[i] = x0;
c1[i+1] = x1;
}
if (!inv_fnt(c1, n, modnum)) {
return 0;
}
for (i = 0; i < n-3; i += 4) {
mpd_uint_t x0 = c1[i];
mpd_uint_t x1 = c1[i+1];
mpd_uint_t x2 = c1[i+2];
mpd_uint_t x3 = c1[i+3];
MULMOD2C(&x0, &x1, n_inv);
MULMOD2C(&x2, &x3, n_inv);
c1[i] = x0;
c1[i+1] = x1;
c1[i+2] = x2;
c1[i+3] = x3;
}
return 1;
}