| 1 | /* mpz_sqrt(root, u) -- Set ROOT to floor(sqrt(U)). |
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| 2 | |
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| 3 | Copyright 1991, 1993, 1994, 1996, 2000, 2001 Free Software Foundation, Inc. |
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| 4 | |
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| 5 | This file is part of the GNU MP Library. |
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| 6 | |
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| 7 | The GNU MP Library is free software; you can redistribute it and/or modify |
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| 8 | it under the terms of the GNU Lesser General Public License as published by |
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| 9 | the Free Software Foundation; either version 2.1 of the License, or (at your |
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| 10 | option) any later version. |
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| 11 | |
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| 12 | The GNU MP Library is distributed in the hope that it will be useful, but |
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| 13 | WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
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| 14 | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
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| 15 | License for more details. |
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| 16 | |
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| 17 | You should have received a copy of the GNU Lesser General Public License |
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| 18 | along with the GNU MP Library; see the file COPYING.LIB. If not, write to |
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| 19 | the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
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| 20 | MA 02111-1307, USA. */ |
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| 21 | |
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| 22 | #include <stdio.h> /* for NULL */ |
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| 23 | #include "gmp.h" |
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| 24 | #include "gmp-impl.h" |
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| 25 | |
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| 26 | void |
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| 27 | mpz_sqrt (mpz_ptr root, mpz_srcptr op) |
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| 28 | { |
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| 29 | mp_size_t op_size, root_size; |
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| 30 | mp_ptr root_ptr, op_ptr; |
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| 31 | mp_ptr free_me = NULL; |
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| 32 | mp_size_t free_me_size; |
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| 33 | TMP_DECL (marker); |
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| 34 | |
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| 35 | TMP_MARK (marker); |
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| 36 | op_size = op->_mp_size; |
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| 37 | if (op_size <= 0) |
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| 38 | { |
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| 39 | if (op_size < 0) |
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| 40 | SQRT_OF_NEGATIVE; |
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| 41 | SIZ(root) = 0; |
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| 42 | return; |
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| 43 | } |
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| 44 | |
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| 45 | /* The size of the root is accurate after this simple calculation. */ |
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| 46 | root_size = (op_size + 1) / 2; |
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| 47 | |
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| 48 | root_ptr = root->_mp_d; |
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| 49 | op_ptr = op->_mp_d; |
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| 50 | |
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| 51 | if (root->_mp_alloc < root_size) |
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| 52 | { |
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| 53 | if (root_ptr == op_ptr) |
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| 54 | { |
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| 55 | free_me = root_ptr; |
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| 56 | free_me_size = root->_mp_alloc; |
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| 57 | } |
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| 58 | else |
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| 59 | (*__gmp_free_func) (root_ptr, root->_mp_alloc * BYTES_PER_MP_LIMB); |
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| 60 | |
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| 61 | root->_mp_alloc = root_size; |
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| 62 | root_ptr = (mp_ptr) (*__gmp_allocate_func) (root_size * BYTES_PER_MP_LIMB); |
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| 63 | root->_mp_d = root_ptr; |
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| 64 | } |
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| 65 | else |
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| 66 | { |
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| 67 | /* Make OP not overlap with ROOT. */ |
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| 68 | if (root_ptr == op_ptr) |
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| 69 | { |
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| 70 | /* ROOT and OP are identical. Allocate temporary space for OP. */ |
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| 71 | op_ptr = (mp_ptr) TMP_ALLOC (op_size * BYTES_PER_MP_LIMB); |
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| 72 | /* Copy to the temporary space. Hack: Avoid temporary variable |
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| 73 | by using ROOT_PTR. */ |
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| 74 | MPN_COPY (op_ptr, root_ptr, op_size); |
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| 75 | } |
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| 76 | } |
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| 77 | |
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| 78 | mpn_sqrtrem (root_ptr, NULL, op_ptr, op_size); |
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| 79 | |
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| 80 | root->_mp_size = root_size; |
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| 81 | |
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| 82 | if (free_me != NULL) |
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| 83 | (*__gmp_free_func) (free_me, free_me_size * BYTES_PER_MP_LIMB); |
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| 84 | TMP_FREE (marker); |
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| 85 | } |
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