1  /* mpfr_sqrt_ui -- square root of a machine integer
       2  
       3  Copyright 2000-2004, 2006-2023 Free Software Foundation, Inc.
       4  Contributed by the AriC and Caramba projects, INRIA.
       5  
       6  This file is part of the GNU MPFR Library.
       7  
       8  The GNU MPFR Library is free software; you can redistribute it and/or modify
       9  it under the terms of the GNU Lesser General Public License as published by
      10  the Free Software Foundation; either version 3 of the License, or (at your
      11  option) any later version.
      12  
      13  The GNU MPFR Library is distributed in the hope that it will be useful, but
      14  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
      15  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
      16  License for more details.
      17  
      18  You should have received a copy of the GNU Lesser General Public License
      19  along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
      20  https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
      21  51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
      22  
      23  #define MPFR_NEED_LONGLONG_H
      24  #include "mpfr-impl.h"
      25  
      26  int
      27  mpfr_sqrt_ui (mpfr_ptr r, unsigned long u, mpfr_rnd_t rnd_mode)
      28  {
      29    int inex;
      30  
      31    MPFR_LOG_FUNC
      32      (("u=%lu rnd=%d", u, rnd_mode),
      33       ("y[%Pd]=%.*Rg inexact=%d",
      34        mpfr_get_prec(r), mpfr_log_prec, r, inex));
      35  
      36    if (u != 0)
      37      {
      38        mpfr_t uu;
      39  #ifdef MPFR_LONG_WITHIN_LIMB
      40        mp_limb_t up[1];
      41        int cnt;
      42        MPFR_SAVE_EXPO_DECL (expo);
      43  
      44        MPFR_TMP_INIT1 (up, uu, GMP_NUMB_BITS);
      45        MPFR_ASSERTN (u == (mp_limb_t) u);
      46        count_leading_zeros (cnt, (mp_limb_t) u);
      47        *up = (mp_limb_t) u << cnt;
      48  
      49        MPFR_SAVE_EXPO_MARK (expo);
      50        MPFR_SET_EXP (uu, GMP_NUMB_BITS - cnt);
      51        inex = mpfr_sqrt (r, uu, rnd_mode);
      52  #else
      53        MPFR_SAVE_EXPO_DECL (expo);
      54  
      55        mpfr_init2 (uu, sizeof (unsigned long) * CHAR_BIT);
      56        /* Warning: u might be outside the current exponent range! */
      57        MPFR_SAVE_EXPO_MARK (expo);
      58        mpfr_set_ui (uu, u, MPFR_RNDZ);
      59        inex = mpfr_sqrt (r, uu, rnd_mode);
      60        mpfr_clear (uu);
      61  #endif /* MPFR_LONG_WITHIN_LIMB */
      62        MPFR_SAVE_EXPO_FREE (expo);
      63        inex = mpfr_check_range (r, inex, rnd_mode);
      64        return inex;
      65      }
      66    else /* sqrt(0) = 0 */
      67      {
      68        MPFR_SET_ZERO(r);
      69        MPFR_SET_POS(r);
      70        MPFR_RET(0);
      71      }
      72  }