1 /* Functions needed for bootstrapping the gmp build, based on mini-gmp. 2 3 Copyright 2001, 2002, 2004, 2011, 2012 Free Software Foundation, Inc. 4 5 This file is part of the GNU MP Library. 6 7 The GNU MP Library is free software; you can redistribute it and/or modify 8 it under the terms of either: 9 10 * the GNU Lesser General Public License as published by the Free 11 Software Foundation; either version 3 of the License, or (at your 12 option) any later version. 13 14 or 15 16 * the GNU General Public License as published by the Free Software 17 Foundation; either version 2 of the License, or (at your option) any 18 later version. 19 20 or both in parallel, as here. 21 22 The GNU MP Library is distributed in the hope that it will be useful, but 23 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 24 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 25 for more details. 26 27 You should have received copies of the GNU General Public License and the 28 GNU Lesser General Public License along with the GNU MP Library. If not, 29 see https://www.gnu.org/licenses/. */ 30 31 32 #include "mini-gmp/mini-gmp.c" 33 34 #define MIN(l,o) ((l) < (o) ? (l) : (o)) 35 #define PTR(x) ((x)->_mp_d) 36 #define SIZ(x) ((x)->_mp_size) 37 38 #define xmalloc gmp_default_alloc 39 40 int 41 isprime (unsigned long int t) 42 { 43 unsigned long int q, r, d; 44 45 if (t < 32) 46 return (0xa08a28acUL >> t) & 1; 47 if ((t & 1) == 0) 48 return 0; 49 50 if (t % 3 == 0) 51 return 0; 52 if (t % 5 == 0) 53 return 0; 54 if (t % 7 == 0) 55 return 0; 56 57 for (d = 11;;) 58 { 59 q = t / d; 60 r = t - q * d; 61 if (q < d) 62 return 1; 63 if (r == 0) 64 break; 65 d += 2; 66 q = t / d; 67 r = t - q * d; 68 if (q < d) 69 return 1; 70 if (r == 0) 71 break; 72 d += 4; 73 } 74 return 0; 75 } 76 77 int 78 log2_ceil (int n) 79 { 80 int e; 81 assert (n >= 1); 82 for (e = 0; ; e++) 83 if ((1 << e) >= n) 84 break; 85 return e; 86 } 87 88 /* Set inv to the inverse of d, in the style of invert_limb, ie. for 89 udiv_qrnnd_preinv. */ 90 void 91 mpz_preinv_invert (mpz_t inv, mpz_t d, int numb_bits) 92 { 93 mpz_t t; 94 int norm; 95 assert (SIZ(d) > 0); 96 97 norm = numb_bits - mpz_sizeinbase (d, 2); 98 assert (norm >= 0); 99 mpz_init_set_ui (t, 1L); 100 mpz_mul_2exp (t, t, 2*numb_bits - norm); 101 mpz_tdiv_q (inv, t, d); 102 mpz_set_ui (t, 1L); 103 mpz_mul_2exp (t, t, numb_bits); 104 mpz_sub (inv, inv, t); 105 106 mpz_clear (t); 107 } 108 109 /* Calculate r satisfying r*d == 1 mod 2^n. */ 110 void 111 mpz_invert_2exp (mpz_t r, mpz_t a, unsigned long n) 112 { 113 unsigned long i; 114 mpz_t inv, prod; 115 116 assert (mpz_odd_p (a)); 117 118 mpz_init_set_ui (inv, 1L); 119 mpz_init (prod); 120 121 for (i = 1; i < n; i++) 122 { 123 mpz_mul (prod, inv, a); 124 if (mpz_tstbit (prod, i) != 0) 125 mpz_setbit (inv, i); 126 } 127 128 mpz_mul (prod, inv, a); 129 mpz_tdiv_r_2exp (prod, prod, n); 130 assert (mpz_cmp_ui (prod, 1L) == 0); 131 132 mpz_set (r, inv); 133 134 mpz_clear (inv); 135 mpz_clear (prod); 136 } 137 138 /* Calculate inv satisfying r*a == 1 mod 2^n. */ 139 void 140 mpz_invert_ui_2exp (mpz_t r, unsigned long a, unsigned long n) 141 { 142 mpz_t az; 143 mpz_init_set_ui (az, a); 144 mpz_invert_2exp (r, az, n); 145 mpz_clear (az); 146 } 147