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/mpz/urandomm.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 98 insertions(+) create mode 100644 gmp-6.3.0/mpz/urandomm.c (limited to 'gmp-6.3.0/mpz/urandomm.c') diff --git a/gmp-6.3.0/mpz/urandomm.c b/gmp-6.3.0/mpz/urandomm.c new file mode 100644 index 0000000..4e6b0ba --- /dev/null +++ b/gmp-6.3.0/mpz/urandomm.c @@ -0,0 +1,98 @@ +/* mpz_urandomm (rop, state, n) -- Generate a uniform pseudorandom + integer in the range 0 to N-1, using STATE as the random state + previously initialized by a call to gmp_randinit(). + +Copyright 2000, 2002, 2012, 2015 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" /* for count_leading_zeros */ + + +#define MAX_URANDOMM_ITER 80 + +void +mpz_urandomm (mpz_ptr rop, gmp_randstate_ptr rstate, mpz_srcptr n) +{ + mp_ptr rp, np; + mp_size_t nbits, size; + mp_limb_t nh; + int count; + int pow2; + int cmp; + TMP_DECL; + + size = ABSIZ (n); + if (UNLIKELY (size == 0)) + DIVIDE_BY_ZERO; + + np = PTR (n); + nh = np[size - 1]; + + /* Detect whether n is a power of 2. */ + pow2 = POW2_P (nh) && (size == 1 || mpn_zero_p (np, size - 1)); + + count_leading_zeros (count, nh); + nbits = size * GMP_NUMB_BITS - (count - GMP_NAIL_BITS) - pow2; + if (nbits == 0) /* nbits == 0 means that n was == 1. */ + { + SIZ (rop) = 0; + return; + } + + TMP_MARK; + if (rop == n) + { + mp_ptr tp; + tp = TMP_ALLOC_LIMBS (size); + MPN_COPY (tp, np, size); + np = tp; + } + + /* Here the allocated size can be one too much if n is a power of + (2^GMP_NUMB_BITS) but it's convenient for using mpn_cmp below. */ + rp = MPZ_NEWALLOC (rop, size); + /* Clear last limb to prevent the case in which size is one too much. */ + rp[size - 1] = 0; + + count = MAX_URANDOMM_ITER; /* Set iteration count limit. */ + do + { + _gmp_rand (rp, rstate, nbits); + MPN_CMP (cmp, rp, np, size); + } + while (cmp >= 0 && --count != 0); + + if (count == 0) + /* Too many iterations; return result mod n == result - n */ + mpn_sub_n (rp, rp, np, size); + + MPN_NORMALIZE (rp, size); + SIZ (rop) = size; + TMP_FREE; +} -- cgit v1.2.3