From 11da511c784eca003deb90c23570f0873954e0de Mon Sep 17 00:00:00 2001 From: Duncan Wilkie Date: Sat, 18 Nov 2023 06:11:09 -0600 Subject: Initial commit. --- gmp-6.3.0/mpn/generic/mod_1_2.c | 148 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 148 insertions(+) create mode 100644 gmp-6.3.0/mpn/generic/mod_1_2.c (limited to 'gmp-6.3.0/mpn/generic/mod_1_2.c') diff --git a/gmp-6.3.0/mpn/generic/mod_1_2.c b/gmp-6.3.0/mpn/generic/mod_1_2.c new file mode 100644 index 0000000..b00d19e --- /dev/null +++ b/gmp-6.3.0/mpn/generic/mod_1_2.c @@ -0,0 +1,148 @@ +/* mpn_mod_1s_2p (ap, n, b, cps) + Divide (ap,,n) by b. Return the single-limb remainder. + Requires that b < B / 2. + + Contributed to the GNU project by Torbjorn Granlund. + Based on a suggestion by Peter L. Montgomery. + + THE FUNCTIONS IN THIS FILE ARE INTERNAL WITH MUTABLE INTERFACES. IT IS ONLY + SAFE TO REACH THEM THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST + GUARANTEED THAT THEY WILL CHANGE OR DISAPPEAR IN A FUTURE GNU MP RELEASE. + +Copyright 2008-2010 Free Software Foundation, Inc. + +This file is part of the GNU MP Library. + +The GNU MP Library is free software; you can redistribute it and/or modify +it under the terms of either: + + * the GNU Lesser General Public License as published by the Free + Software Foundation; either version 3 of the License, or (at your + option) any later version. + +or + + * 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. + +or both in parallel, as here. + +The GNU MP Library 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 copies of the GNU General Public License and the +GNU Lesser General Public License along with the GNU MP Library. If not, +see https://www.gnu.org/licenses/. */ + +#include "gmp-impl.h" +#include "longlong.h" + +void +mpn_mod_1s_2p_cps (mp_limb_t cps[5], mp_limb_t b) +{ + mp_limb_t bi; + mp_limb_t B1modb, B2modb, B3modb; + int cnt; + + ASSERT (b <= (~(mp_limb_t) 0) / 2); + + count_leading_zeros (cnt, b); + + b <<= cnt; + invert_limb (bi, b); + + cps[0] = bi; + cps[1] = cnt; + + B1modb = -b * ((bi >> (GMP_LIMB_BITS-cnt)) | (CNST_LIMB(1) << cnt)); + ASSERT (B1modb <= b); /* NB: not fully reduced mod b */ + cps[2] = B1modb >> cnt; + + udiv_rnnd_preinv (B2modb, B1modb, CNST_LIMB(0), b, bi); + cps[3] = B2modb >> cnt; + + udiv_rnnd_preinv (B3modb, B2modb, CNST_LIMB(0), b, bi); + cps[4] = B3modb >> cnt; + +#if WANT_ASSERT + { + int i; + b = cps[2]; + for (i = 3; i <= 4; i++) + { + b += cps[i]; + ASSERT (b >= cps[i]); + } + } +#endif +} + +mp_limb_t +mpn_mod_1s_2p (mp_srcptr ap, mp_size_t n, mp_limb_t b, const mp_limb_t cps[5]) +{ + mp_limb_t rh, rl, bi, ph, pl, ch, cl, r; + mp_limb_t B1modb, B2modb, B3modb; + mp_size_t i; + int cnt; + + ASSERT (n >= 1); + + B1modb = cps[2]; + B2modb = cps[3]; + B3modb = cps[4]; + + if ((n & 1) != 0) + { + if (n == 1) + { + rl = ap[n - 1]; + bi = cps[0]; + cnt = cps[1]; + udiv_rnnd_preinv (r, rl >> (GMP_LIMB_BITS - cnt), + rl << cnt, b, bi); + return r >> cnt; + } + + umul_ppmm (ph, pl, ap[n - 2], B1modb); + add_ssaaaa (ph, pl, ph, pl, CNST_LIMB(0), ap[n - 3]); + umul_ppmm (rh, rl, ap[n - 1], B2modb); + add_ssaaaa (rh, rl, rh, rl, ph, pl); + n--; + } + else + { + rh = ap[n - 1]; + rl = ap[n - 2]; + } + + for (i = n - 4; i >= 0; i -= 2) + { + /* rr = ap[i] < B + + ap[i+1] * (B mod b) <= (B-1)(b-1) + + LO(rr) * (B^2 mod b) <= (B-1)(b-1) + + HI(rr) * (B^3 mod b) <= (B-1)(b-1) + */ + umul_ppmm (ph, pl, ap[i + 1], B1modb); + add_ssaaaa (ph, pl, ph, pl, CNST_LIMB(0), ap[i + 0]); + + umul_ppmm (ch, cl, rl, B2modb); + add_ssaaaa (ph, pl, ph, pl, ch, cl); + + umul_ppmm (rh, rl, rh, B3modb); + add_ssaaaa (rh, rl, rh, rl, ph, pl); + } + + umul_ppmm (rh, cl, rh, B1modb); + add_ssaaaa (rh, rl, rh, rl, CNST_LIMB(0), cl); + + cnt = cps[1]; + bi = cps[0]; + + r = (rh << cnt) | (rl >> (GMP_LIMB_BITS - cnt)); + udiv_rnnd_preinv (r, r, rl << cnt, b, bi); + + return r >> cnt; +} -- cgit v1.2.3