mirror of https://github.com/macssh/macssh.git
118 lines
2.8 KiB
C
Executable File
118 lines
2.8 KiB
C
Executable File
/* mpz_rrandomb -- Generate a positive random mpz_t of specified bit size, with
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long runs of consecutive ones and zeros in the binary representation.
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Meant for testing of other MP routines.
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Copyright (C) 2000 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
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MA 02111-1307, USA. */
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#include "gmp.h"
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#include "gmp-impl.h"
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static void gmp_rrandomb _PROTO ((mp_ptr rp, gmp_randstate_t rstate, unsigned long int nbits));
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void
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#if __STDC__
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mpz_rrandomb (mpz_ptr x, gmp_randstate_t rstate, unsigned long int nbits)
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#else
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mpz_rrandomb (x, rstate, nbits)
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mpz_ptr x;
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gmp_randstate_t rstate;
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unsigned long int nbits;
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#endif
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{
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mp_size_t nl = 0;
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if (nbits != 0)
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{
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mp_ptr xp;
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nl = (nbits + BITS_PER_MP_LIMB - 1) / BITS_PER_MP_LIMB;
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if (x->_mp_alloc < nl)
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_mpz_realloc (x, nl);
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xp = PTR(x);
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gmp_rrandomb (xp, rstate, nbits);
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MPN_NORMALIZE (xp, nl);
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}
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SIZ(x) = nl;
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}
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#define BITS_PER_CHUNK 4
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static void
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#if __STDC__
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gmp_rrandomb (mp_ptr rp, gmp_randstate_t rstate, unsigned long int nbits)
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#else
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gmp_rrandomb (rp, rstate, nbits)
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mp_ptr rp;
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gmp_randstate_t rstate;
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unsigned long int nbits;
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#endif
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{
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int nb;
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int bit_pos;
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mp_size_t limb_pos;
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mp_limb_t ran, ranm;
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mp_limb_t acc;
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mp_size_t n;
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bit_pos = nbits % BITS_PER_MP_LIMB;
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limb_pos = nbits / BITS_PER_MP_LIMB;
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if (bit_pos == 0)
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{
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bit_pos = BITS_PER_MP_LIMB;
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limb_pos--;
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}
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acc = 0;
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while (limb_pos >= 0)
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{
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_gmp_rand (&ranm, rstate, BITS_PER_CHUNK + 1);
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ran = ranm;
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nb = (ran >> 1) + 1;
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if ((ran & 1) != 0)
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{
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/* Generate a string of ones. */
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if (nb > bit_pos)
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{
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rp[limb_pos--] = acc | ((((mp_limb_t) 1) << bit_pos) - 1);
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bit_pos += BITS_PER_MP_LIMB;
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bit_pos -= nb;
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acc = (~(mp_limb_t) 0) << bit_pos;
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}
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else
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{
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bit_pos -= nb;
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acc |= ((((mp_limb_t) 1) << nb) - 1) << bit_pos;
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}
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}
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else
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{
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/* Generate a string of zeroes. */
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if (nb > bit_pos)
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{
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rp[limb_pos--] = acc;
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acc = 0;
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bit_pos += BITS_PER_MP_LIMB;
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}
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bit_pos -= nb;
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}
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}
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}
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