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1996-09-27 06:29:02 -04:00
/* mpz_sqrt(root, u) -- Set ROOT to floor(sqrt(U)).
Copyright (C) 1991 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
The GNU MP Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with the GNU MP Library; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
/* This code is just correct if "unsigned char" has at least 8 bits. It
doesn't help to use CHAR_BIT from limits.h, as the real problem is
the static arrays. */
#include "gmp.h"
#include "gmp-impl.h"
#ifdef __STDC__
mpz_sqrt (MP_INT *root, const MP_INT *op)
mpz_sqrt (root, op)
MP_INT *root;
const MP_INT *op;
mp_size op_size, root_size;
mp_ptr root_ptr, op_ptr;
mp_ptr free_me = NULL;
mp_size free_me_size;
op_size = op->size;
if (op_size < 0)
op_size = 1 / op_size > 0; /* Divide by zero for negative OP. */
/* The size of the root is accurate after this simple calculation. */
root_size = (op_size + 1) / 2;
root_ptr = root->d;
op_ptr = op->d;
if (root->alloc < root_size)
if (root_ptr == op_ptr)
free_me = root_ptr;
free_me_size = root->alloc;
(*_mp_free_func) (root_ptr, root->alloc * BYTES_PER_MP_LIMB);
root->alloc = root_size;
root_ptr = (mp_ptr) (*_mp_allocate_func) (root_size * BYTES_PER_MP_LIMB);
root->d = root_ptr;
/* Make OP not overlap with ROOT. */
if (root_ptr == op_ptr)
/* ROOT and OP are identical. Allocate temporary space for OP. */
op_ptr = (mp_ptr) alloca (op_size * BYTES_PER_MP_LIMB);
/* Copy to the temporary space. Hack: Avoid temporary variable
by using ROOT_PTR. */
MPN_COPY (op_ptr, root_ptr, op_size);
mpn_sqrt (root_ptr, NULL, op_ptr, op_size);
root->size = root_size;
if (free_me != NULL)
(*_mp_free_func) (free_me, free_me_size * BYTES_PER_MP_LIMB);
alloca (0);