aa9bc17601
BMakefiles and other bits will follow. Requested by: Andrey Chernov Made world by: Chuck Robey
94 lines
2.7 KiB
C
94 lines
2.7 KiB
C
/* mpn_random2 -- Generate random numbers with relatively long strings
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of ones and zeroes. Suitable for border testing.
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Copyright (C) 1992, 1993, 1994, 1996 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 Library General Public License as published by
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the Free Software Foundation; either version 2 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 Library General Public
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License for more details.
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You should have received a copy of the GNU Library 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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#if defined (__hpux) || defined (alpha__) || defined (__svr4__) || defined (__SVR4)
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/* HPUX lacks random(). DEC OSF/1 1.2 random() returns a double. */
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long mrand48 ();
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static inline long
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random ()
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{
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return mrand48 ();
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}
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#else
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long random ();
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#endif
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/* It's a bit tricky to get this right, so please test the code well
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if you hack with it. Some early versions of the function produced
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random numbers with the leading limb == 0, and some versions never
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made the most significant bit set. */
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void
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mpn_random2 (res_ptr, size)
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mp_ptr res_ptr;
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mp_size_t size;
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{
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int n_bits;
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int bit_pos;
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mp_size_t limb_pos;
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unsigned int ran;
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mp_limb_t limb;
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limb = 0;
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/* Start off in a random bit position in the most significant limb. */
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bit_pos = random () & (BITS_PER_MP_LIMB - 1);
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/* Least significant bit of RAN chooses string of ones/string of zeroes.
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Make most significant limb be non-zero by setting bit 0 of RAN. */
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ran = random () | 1;
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for (limb_pos = size - 1; limb_pos >= 0; )
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{
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n_bits = (ran >> 1) % BITS_PER_MP_LIMB + 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 (n_bits >= bit_pos)
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{
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res_ptr[limb_pos--] = limb | ((((mp_limb_t) 2) << bit_pos) - 1);
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bit_pos += BITS_PER_MP_LIMB;
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limb = (~(mp_limb_t) 0) << (bit_pos - n_bits);
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}
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else
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{
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limb |= ((((mp_limb_t) 1) << n_bits) - 1) << (bit_pos - n_bits + 1);
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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 (n_bits >= bit_pos)
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{
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res_ptr[limb_pos--] = limb;
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limb = 0;
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bit_pos += BITS_PER_MP_LIMB;
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}
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}
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bit_pos -= n_bits;
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ran = random ();
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}
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}
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