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