source/libs/gmp/gmp-src/mpz/sqrtrem.c

   1 /* mpz_sqrtrem(root,rem,x) -- Set ROOT to floor(sqrt(X)) and REM
   2    to the remainder, i.e. X - ROOT**2.
   3
   4 Copyright 1991, 1993, 1994, 1996, 2000, 2001, 2005, 2011, 2012 Free Software
   5 Foundation, Inc.
   6
   7 This file is part of the GNU MP Library.
   8
   9 The GNU MP Library is free software; you can redistribute it and/or modify
  10 it under the terms of either:
  11
  12   * the GNU Lesser General Public License as published by the Free
  13     Software Foundation; either version 3 of the License, or (at your
  14     option) any later version.
  15
  16 or
  17
  18   * the GNU General Public License as published by the Free Software
  19     Foundation; either version 2 of the License, or (at your option) any
  20     later version.
  21
  22 or both in parallel, as here.
  23
  24 The GNU MP Library is distributed in the hope that it will be useful, but
  25 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  26 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  27 for more details.
  28
  29 You should have received copies of the GNU General Public License and the
  30 GNU Lesser General Public License along with the GNU MP Library.  If not,
  31 see https://www.gnu.org/licenses/.  */
  32
  33 #include "gmp.h"
  34 #include "gmp-impl.h"
  35
  36 void
  37 mpz_sqrtrem (mpz_ptr root, mpz_ptr rem, mpz_srcptr op)
  38 {
  39   mp_size_t op_size, root_size, rem_size;
  40   mp_ptr root_ptr, op_ptr, rem_ptr;
  41
  42   op_size = SIZ (op);
  43   if (UNLIKELY (op_size <= 0))
  44     {
  45       if (op_size < 0)
  46         SQRT_OF_NEGATIVE;
  47       SIZ(root) = 0;
  48       SIZ(rem) = 0;
  49       return;
  50     }
  51
  52   rem_ptr = MPZ_REALLOC (rem, op_size);
  53
  54   /* The size of the root is accurate after this simple calculation.  */
  55   root_size = (op_size + 1) / 2;
  56   SIZ (root) = root_size;
  57
  58   op_ptr = PTR (op);
  59
  60   if (root == op)
  61     {
  62       /* Allocate temp space for the root, which we then copy to the
  63          shared OP/ROOT variable.  */
  64       TMP_DECL;
  65       TMP_MARK;
  66
  67       root_ptr = TMP_ALLOC_LIMBS (root_size);
  68       rem_size = mpn_sqrtrem (root_ptr, rem_ptr, op_ptr, op_size);
  69
  70       if (rem != root)  /* Don't overwrite remainder */
  71         MPN_COPY (op_ptr, root_ptr, root_size);
  72
  73       TMP_FREE;
  74     }
  75   else
  76     {
  77       root_ptr = MPZ_NEWALLOC (root, root_size);
  78
  79       rem_size = mpn_sqrtrem (root_ptr, rem_ptr, op_ptr, op_size);
  80     }
  81
  82   /* Write remainder size last, to make this function give only the square root
  83      remainder, when passed ROOT == REM.  */
  84   SIZ (rem) = rem_size;
  85 }