contrib/gmp/randlc2s.c

   1 /* gmp_randinit_lc_2exp_size -- initialize a random state with a linear
   2    congruential generator of a requested size.
   3
   4 Copyright 1999, 2000, 2001 Free Software Foundation, Inc.
   5
   6 This file is part of the GNU MP Library.
   7
   8 The GNU MP Library is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU Lesser General Public License as published by
  10 the Free Software Foundation; either version 3 of the License, or (at your
  11 option) any later version.
  12
  13 The GNU MP Library is distributed in the hope that it will be useful, but
  14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  15 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  16 License for more details.
  17
  18 You should have received a copy of the GNU Lesser General Public License
  19 along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */
  20
  21 #include <stdio.h> /* for NULL */
  22 #include "gmp.h"
  23 #include "gmp-impl.h"
  24
  25
  26 /* Array of LC-schemes, ordered in increasing order of the first
  27    member (the 'm2exp' value).  The end of the array is indicated with
  28    an entry containing all zeros.  */
  29
  30 /* All multipliers are in the range 0.01*m and 0.99*m, and are
  31 congruent to 5 (mod 8).
  32 They all pass the spectral test with Vt >= 2^(30/t) and merit >= 1.
  33 (Up to and including 196 bits, merit is >= 3.)  */
  34
  35 struct __gmp_rand_lc_scheme_struct
  36 {
  37   unsigned long int m2exp;      /* Modulus is 2 ^ m2exp. */
  38   const char *astr;             /* Multiplier in string form. */
  39   unsigned long int c;          /* Addend. */
  40 };
  41
  42 static const struct __gmp_rand_lc_scheme_struct __gmp_rand_lc_scheme[] =
  43 {
  44   {32, "29CF535",            1},
  45   {33, "51F666D",            1},
  46   {34, "A3D73AD",            1},
  47   {35, "147E5B85",           1},
  48   {36, "28F725C5",           1},
  49   {37, "51EE3105",           1},
  50   {38, "A3DD5CDD",           1},
  51   {39, "147AF833D",          1},
  52   {40, "28F5DA175",          1},
  53   {56, "AA7D735234C0DD",  1},
  54   {64, "BAECD515DAF0B49D", 1},
  55   {100, "292787EBD3329AD7E7575E2FD", 1},
  56   {128, "48A74F367FA7B5C8ACBB36901308FA85", 1},
  57   {156, "78A7FDDDC43611B527C3F1D760F36E5D7FC7C45", 1},
  58   {196, "41BA2E104EE34C66B3520CE706A56498DE6D44721E5E24F5", 1},
  59   {200, "4E5A24C38B981EAFE84CD9D0BEC48E83911362C114F30072C5", 1},
  60   {256, "AF66BA932AAF58A071FD8F0742A99A0C76982D648509973DB802303128A14CB5", 1},
  61   {0, NULL, 0}                  /* End of array. */
  62 };
  63
  64 int
  65 gmp_randinit_lc_2exp_size (gmp_randstate_t rstate, mp_bitcnt_t size)
  66 {
  67   const struct __gmp_rand_lc_scheme_struct *sp;
  68   mpz_t a;
  69
  70   /* Pick a scheme.  */
  71   for (sp = __gmp_rand_lc_scheme; sp->m2exp != 0; sp++)
  72     if (sp->m2exp / 2 >= size)
  73       goto found;
  74   return 0;
  75
  76  found:
  77   /* Install scheme.  */
  78   mpz_init_set_str (a, sp->astr, 16);
  79   gmp_randinit_lc_2exp (rstate, a, sp->c, sp->m2exp);
  80   mpz_clear (a);
  81   return 1;
  82 }