cosmopolitan/third_party/python/Modules/_decimal/libmpdec/fourstep.c
Justine Tunney 9b29358511 Make whitespace changes
Status lines for Emacs and Vim have been added to Python sources so
they'll be easier to edit using Python's preferred coding style.

Some DNS helper functions have been broken up into multiple files. It's
nice to have one function per file whenever possible, since that way we
don't need -ffunction-sections.  Another reason it's good to have small
source files, is because the build will be enforcing resource limits on
compilation and testing soon.
2021-08-13 03:20:45 -07:00

261 lines
8.1 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:4;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=4 sts=4 sw=4 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright (c) 2008-2016 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 "third_party/python/Modules/_decimal/libmpdec/fourstep.h"
#include "third_party/python/Modules/_decimal/libmpdec/mpdecimal.h"
#include "third_party/python/Modules/_decimal/libmpdec/numbertheory.h"
#include "third_party/python/Modules/_decimal/libmpdec/sixstep.h"
#include "third_party/python/Modules/_decimal/libmpdec/transpose.h"
#include "third_party/python/Modules/_decimal/libmpdec/umodarith.h"
/* clang-format off */
asm(".ident\t\"\\n\\n\
libmpdec (BSD-2)\\n\
Copyright 2008-2016 Stefan Krah\"");
asm(".include \"libc/disclaimer.inc\"");
/* Bignum: Cache efficient Matrix Fourier Transform for arrays of the
form 3 * 2**n (See literature/matrix-transform.txt). */
#ifndef PPRO
static inline void
std_size3_ntt(mpd_uint_t *x1, mpd_uint_t *x2, mpd_uint_t *x3,
mpd_uint_t w3table[3], mpd_uint_t umod)
{
mpd_uint_t r1, r2;
mpd_uint_t w;
mpd_uint_t s, tmp;
/* k = 0 -> w = 1 */
s = *x1;
s = addmod(s, *x2, umod);
s = addmod(s, *x3, umod);
r1 = s;
/* k = 1 */
s = *x1;
w = w3table[1];
tmp = MULMOD(*x2, w);
s = addmod(s, tmp, umod);
w = w3table[2];
tmp = MULMOD(*x3, w);
s = addmod(s, tmp, umod);
r2 = s;
/* k = 2 */
s = *x1;
w = w3table[2];
tmp = MULMOD(*x2, w);
s = addmod(s, tmp, umod);
w = w3table[1];
tmp = MULMOD(*x3, w);
s = addmod(s, tmp, umod);
*x3 = s;
*x2 = r2;
*x1 = r1;
}
#else /* PPRO */
static inline void
ppro_size3_ntt(mpd_uint_t *x1, mpd_uint_t *x2, mpd_uint_t *x3, mpd_uint_t w3table[3],
mpd_uint_t umod, double *dmod, uint32_t dinvmod[3])
{
mpd_uint_t r1, r2;
mpd_uint_t w;
mpd_uint_t s, tmp;
/* k = 0 -> w = 1 */
s = *x1;
s = addmod(s, *x2, umod);
s = addmod(s, *x3, umod);
r1 = s;
/* k = 1 */
s = *x1;
w = w3table[1];
tmp = ppro_mulmod(*x2, w, dmod, dinvmod);
s = addmod(s, tmp, umod);
w = w3table[2];
tmp = ppro_mulmod(*x3, w, dmod, dinvmod);
s = addmod(s, tmp, umod);
r2 = s;
/* k = 2 */
s = *x1;
w = w3table[2];
tmp = ppro_mulmod(*x2, w, dmod, dinvmod);
s = addmod(s, tmp, umod);
w = w3table[1];
tmp = ppro_mulmod(*x3, w, dmod, dinvmod);
s = addmod(s, tmp, umod);
*x3 = s;
*x2 = r2;
*x1 = r1;
}
#endif
/* forward transform, sign = -1; transform length = 3 * 2**n */
int
four_step_fnt(mpd_uint_t *a, mpd_size_t n, int modnum)
{
mpd_size_t R = 3; /* number of rows */
mpd_size_t C = n / 3; /* number of columns */
mpd_uint_t w3table[3];
mpd_uint_t kernel, w0, w1, wstep;
mpd_uint_t *s, *p0, *p1, *p2;
mpd_uint_t umod;
#ifdef PPRO
double dmod;
uint32_t dinvmod[3];
#endif
mpd_size_t i, k;
assert(n >= 48);
assert(n <= 3*MPD_MAXTRANSFORM_2N);
/* Length R transform on the columns. */
SETMODULUS(modnum);
_mpd_init_w3table(w3table, -1, modnum);
for (p0=a, p1=p0+C, p2=p0+2*C; p0<a+C; p0++,p1++,p2++) {
SIZE3_NTT(p0, p1, p2, w3table);
}
/* Multiply each matrix element (addressed by i*C+k) by r**(i*k). */
kernel = _mpd_getkernel(n, -1, modnum);
for (i = 1; i < R; i++) {
w0 = 1; /* r**(i*0): initial value for k=0 */
w1 = POWMOD(kernel, i); /* r**(i*1): initial value for k=1 */
wstep = MULMOD(w1, w1); /* r**(2*i) */
for (k = 0; k < C-1; k += 2) {
mpd_uint_t x0 = a[i*C+k];
mpd_uint_t x1 = a[i*C+k+1];
MULMOD2(&x0, w0, &x1, w1);
MULMOD2C(&w0, &w1, wstep); /* r**(i*(k+2)) = r**(i*k) * r**(2*i) */
a[i*C+k] = x0;
a[i*C+k+1] = x1;
}
}
/* Length C transform on the rows. */
for (s = a; s < a+n; s += C) {
if (!six_step_fnt(s, C, modnum)) {
return 0;
}
}
#if 0
/* An unordered transform is sufficient for convolution. */
/* Transpose the matrix. */
transpose_3xpow2(a, R, C);
#endif
return 1;
}
/* backward transform, sign = 1; transform length = 3 * 2**n */
int
inv_four_step_fnt(mpd_uint_t *a, mpd_size_t n, int modnum)
{
mpd_size_t R = 3; /* number of rows */
mpd_size_t C = n / 3; /* number of columns */
mpd_uint_t w3table[3];
mpd_uint_t kernel, w0, w1, wstep;
mpd_uint_t *s, *p0, *p1, *p2;
mpd_uint_t umod;
#ifdef PPRO
double dmod;
uint32_t dinvmod[3];
#endif
mpd_size_t i, k;
assert(n >= 48);
assert(n <= 3*MPD_MAXTRANSFORM_2N);
#if 0
/* An unordered transform is sufficient for convolution. */
/* Transpose the matrix, producing an R*C matrix. */
transpose_3xpow2(a, C, R);
#endif
/* Length C transform on the rows. */
for (s = a; s < a+n; s += C) {
if (!inv_six_step_fnt(s, C, modnum)) {
return 0;
}
}
/* Multiply each matrix element (addressed by i*C+k) by r**(i*k). */
SETMODULUS(modnum);
kernel = _mpd_getkernel(n, 1, modnum);
for (i = 1; i < R; i++) {
w0 = 1;
w1 = POWMOD(kernel, i);
wstep = MULMOD(w1, w1);
for (k = 0; k < C; k += 2) {
mpd_uint_t x0 = a[i*C+k];
mpd_uint_t x1 = a[i*C+k+1];
MULMOD2(&x0, w0, &x1, w1);
MULMOD2C(&w0, &w1, wstep);
a[i*C+k] = x0;
a[i*C+k+1] = x1;
}
}
/* Length R transform on the columns. */
_mpd_init_w3table(w3table, 1, modnum);
for (p0=a, p1=p0+C, p2=p0+2*C; p0<a+C; p0++,p1++,p2++) {
SIZE3_NTT(p0, p1, p2, w3table);
}
return 1;
}