1/* mpz_sqrt(root, u) --  Set ROOT to floor(sqrt(U)).
2
3Copyright 1991, 1993, 1994, 1996, 2000, 2001, 2005 Free Software Foundation,
4Inc.
5
6This file is part of the GNU MP Library.
7
8The GNU MP Library is free software; you can redistribute it and/or modify
9it under the terms of the GNU Lesser General Public License as published by
10the Free Software Foundation; either version 3 of the License, or (at your
11option) any later version.
12
13The GNU MP Library is distributed in the hope that it will be useful, but
14WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
16License for more details.
17
18You should have received a copy of the GNU Lesser General Public License
19along 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
25void
26mpz_sqrt (mpz_ptr root, mpz_srcptr op)
27{
28  mp_size_t op_size, root_size;
29  mp_ptr root_ptr, op_ptr;
30  mp_ptr free_me = NULL;
31  mp_size_t free_me_size;
32  TMP_DECL;
33
34  TMP_MARK;
35  op_size = op->_mp_size;
36  if (op_size <= 0)
37    {
38      if (op_size < 0)
39        SQRT_OF_NEGATIVE;
40      SIZ(root) = 0;
41      return;
42    }
43
44  /* The size of the root is accurate after this simple calculation.  */
45  root_size = (op_size + 1) / 2;
46
47  root_ptr = root->_mp_d;
48  op_ptr = op->_mp_d;
49
50  if (root->_mp_alloc < root_size)
51    {
52      if (root_ptr == op_ptr)
53	{
54	  free_me = root_ptr;
55	  free_me_size = root->_mp_alloc;
56	}
57      else
58	(*__gmp_free_func) (root_ptr, root->_mp_alloc * BYTES_PER_MP_LIMB);
59
60      root->_mp_alloc = root_size;
61      root_ptr = (mp_ptr) (*__gmp_allocate_func) (root_size * BYTES_PER_MP_LIMB);
62      root->_mp_d = root_ptr;
63    }
64  else
65    {
66      /* Make OP not overlap with ROOT.  */
67      if (root_ptr == op_ptr)
68	{
69	  /* ROOT and OP are identical.  Allocate temporary space for OP.  */
70	  op_ptr = TMP_ALLOC_LIMBS (op_size);
71	  /* Copy to the temporary space.  Hack: Avoid temporary variable
72	     by using ROOT_PTR.  */
73	  MPN_COPY (op_ptr, root_ptr, op_size);
74	}
75    }
76
77  mpn_sqrtrem (root_ptr, NULL, op_ptr, op_size);
78
79  root->_mp_size = root_size;
80
81  if (free_me != NULL)
82    (*__gmp_free_func) (free_me, free_me_size * BYTES_PER_MP_LIMB);
83  TMP_FREE;
84}
85