--- /dev/null
+/* mpfr_random2 -- Generate a positive random mpfr_t of specified size, with
+ long runs of consecutive ones and zeros in the binary representation.
+ Intended for testing.
+
+Copyright 1999, 2001, 2002, 2003, 2004, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+Contributed by the Arenaire and Cacao projects, INRIA.
+
+This file is part of the GNU MPFR Library.
+
+The GNU MPFR Library is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or (at your
+option) any later version.
+
+The GNU MPFR 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 Lesser General Public
+License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with the GNU MPFR Library; see the file COPYING.LIB. If not, write to
+the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+MA 02110-1301, USA. */
+
+#define MPFR_NEED_LONGLONG_H
+#include "mpfr-impl.h"
+
+#define LOGBITS_PER_BLOCK 4
+#if GMP_NUMB_BITS < 32
+#define BITS_PER_RANDCALL GMP_NUMB_BITS
+#else
+#define BITS_PER_RANDCALL 32
+#endif
+
+static void
+mpfr_random2_raw (mpfr_ptr x, mp_size_t size, mp_exp_t exp,
+ gmp_randstate_t rstate)
+{
+ mp_size_t xn, k, ri;
+ unsigned long sh;
+ mp_ptr xp;
+ mp_limb_t elimb, ran, acc;
+ int ran_nbits, bit_pos, nb;
+
+ MPFR_CLEAR_FLAGS (x);
+
+ if (MPFR_UNLIKELY(size == 0))
+ {
+ MPFR_SET_ZERO (x);
+ MPFR_SET_POS (x);
+ return ;
+ }
+ else if (size > 0)
+ {
+ MPFR_SET_POS (x);
+ }
+ else
+ {
+ MPFR_SET_NEG (x);
+ size = -size;
+ }
+
+ xn = MPFR_LIMB_SIZE (x);
+ xp = MPFR_MANT (x);
+ if (size > xn)
+ size = xn;
+ k = xn - size;
+
+ /* Code extracted from GMP, function mpn_random2, to avoid the use
+ of GMP's internal random state in MPFR */
+
+ _gmp_rand (&elimb, rstate, BITS_PER_RANDCALL);
+ ran = elimb;
+
+ /* Start off at a random bit position in the most significant limb. */
+ bit_pos = GMP_NUMB_BITS - 1;
+ ran >>= 6; /* Ideally log2(GMP_NUMB_BITS) */
+ ran_nbits = BITS_PER_RANDCALL - 6; /* Ideally - log2(GMP_NUMB_BITS) */
+
+ /* Bit 0 of ran chooses string of ones/string of zeroes.
+ Make most significant limb be non-zero by setting bit 0 of RAN. */
+ ran |= 1;
+ ri = xn - 1;
+
+ acc = 0;
+ while (ri >= k)
+ {
+ if (ran_nbits < LOGBITS_PER_BLOCK + 1)
+ {
+ _gmp_rand (&elimb, rstate, BITS_PER_RANDCALL);
+ ran = elimb;
+ ran_nbits = BITS_PER_RANDCALL;
+ }
+
+ nb = (ran >> 1) % (1 << LOGBITS_PER_BLOCK) + 1;
+ if ((ran & 1) != 0)
+ {
+ /* Generate a string of nb ones. */
+ if (nb > bit_pos)
+ {
+ xp[ri--] = acc | (((mp_limb_t) 2 << bit_pos) - 1);
+ bit_pos += GMP_NUMB_BITS;
+ bit_pos -= nb;
+ acc = ((~(mp_limb_t) 1) << bit_pos) & GMP_NUMB_MASK;
+ }
+ else
+ {
+ bit_pos -= nb;
+ acc |= (((mp_limb_t) 2 << nb) - 2) << bit_pos;
+ }
+ }
+ else
+ {
+ /* Generate a string of nb zeroes. */
+ if (nb > bit_pos)
+ {
+ xp[ri--] = acc;
+ acc = 0;
+ bit_pos += GMP_NUMB_BITS;
+ }
+ bit_pos -= nb;
+ }
+ ran_nbits -= LOGBITS_PER_BLOCK + 1;
+ ran >>= LOGBITS_PER_BLOCK + 1;
+ }
+
+ /* Set mandatory most significant bit. */
+ /* xp[xn - 1] |= MPFR_LIMB_HIGHBIT; */
+
+ if (k != 0)
+ {
+ /* Clear last limbs */
+ MPN_ZERO (xp, k);
+ }
+ else
+ {
+ /* Mask off non significant bits in the low limb. */
+ MPFR_UNSIGNED_MINUS_MODULO (sh, MPFR_PREC (x));
+ xp[0] &= ~MPFR_LIMB_MASK (sh);
+ }
+
+ /* Generate random exponent. */
+ _gmp_rand (&elimb, RANDS, BITS_PER_MP_LIMB);
+ exp = ABS (exp);
+ MPFR_SET_EXP (x, elimb % (2 * exp + 1) - exp);
+
+ return ;
+}
+
+void
+mpfr_random2 (mpfr_ptr x, mp_size_t size, mp_exp_t exp)
+{
+ mpfr_random2_raw (x, size, exp, RANDS);
+}