86 lines
2.4 KiB
C
86 lines
2.4 KiB
C
/* mpz_sqrt(root, u) -- Set ROOT to floor(sqrt(U)).
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Copyright (C) 1991, 1993, 1994, 1996 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Library General Public License as published by
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the Free Software Foundation; either version 2 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
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License for more details.
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You should have received a copy of the GNU Library General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
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MA 02111-1307, USA. */
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#include "gmp.h"
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#include "gmp-impl.h"
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void
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#if __STDC__
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mpz_sqrt (mpz_ptr root, mpz_srcptr op)
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#else
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mpz_sqrt (root, op)
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mpz_ptr root;
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mpz_srcptr op;
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#endif
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{
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mp_size_t op_size, root_size;
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mp_ptr root_ptr, op_ptr;
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mp_ptr free_me = NULL;
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mp_size_t free_me_size;
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TMP_DECL (marker);
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TMP_MARK (marker);
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op_size = op->_mp_size;
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if (op_size < 0)
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op_size = 1 / (op_size > 0); /* Divide by zero for negative OP. */
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/* The size of the root is accurate after this simple calculation. */
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root_size = (op_size + 1) / 2;
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root_ptr = root->_mp_d;
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op_ptr = op->_mp_d;
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if (root->_mp_alloc < root_size)
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{
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if (root_ptr == op_ptr)
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{
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free_me = root_ptr;
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free_me_size = root->_mp_alloc;
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}
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else
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(*_mp_free_func) (root_ptr, root->_mp_alloc * BYTES_PER_MP_LIMB);
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root->_mp_alloc = root_size;
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root_ptr = (mp_ptr) (*_mp_allocate_func) (root_size * BYTES_PER_MP_LIMB);
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root->_mp_d = root_ptr;
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}
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else
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{
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/* Make OP not overlap with ROOT. */
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if (root_ptr == op_ptr)
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{
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/* ROOT and OP are identical. Allocate temporary space for OP. */
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op_ptr = (mp_ptr) TMP_ALLOC (op_size * BYTES_PER_MP_LIMB);
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/* Copy to the temporary space. Hack: Avoid temporary variable
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by using ROOT_PTR. */
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MPN_COPY (op_ptr, root_ptr, op_size);
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}
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}
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mpn_sqrtrem (root_ptr, NULL, op_ptr, op_size);
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root->_mp_size = root_size;
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if (free_me != NULL)
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(*_mp_free_func) (free_me, free_me_size * BYTES_PER_MP_LIMB);
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TMP_FREE (marker);
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}
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