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Annotation of OpenXM_contrib/gmp/mpf/sqrt.c, Revision 1.1

1.1     ! maekawa     1: /* mpf_sqrt -- Compute the square root of a float.
        !             2:
        !             3: Copyright (C) 1993, 1994, 1996 Free Software Foundation, Inc.
        !             4:
        !             5: This file is part of the GNU MP Library.
        !             6:
        !             7: The GNU MP Library is free software; you can redistribute it and/or modify
        !             8: it under the terms of the GNU Library General Public License as published by
        !             9: the Free Software Foundation; either version 2 of the License, or (at your
        !            10: option) any later version.
        !            11:
        !            12: The GNU MP Library is distributed in the hope that it will be useful, but
        !            13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
        !            14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
        !            15: License for more details.
        !            16:
        !            17: You should have received a copy of the GNU Library General Public License
        !            18: along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
        !            19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
        !            20: MA 02111-1307, USA. */
        !            21:
        !            22: #include "gmp.h"
        !            23: #include "gmp-impl.h"
        !            24:
        !            25: void
        !            26: #if __STDC__
        !            27: mpf_sqrt (mpf_ptr r, mpf_srcptr u)
        !            28: #else
        !            29: mpf_sqrt (r, u)
        !            30:      mpf_ptr r;
        !            31:      mpf_srcptr u;
        !            32: #endif
        !            33: {
        !            34:   mp_size_t usize;
        !            35:   mp_ptr up, tp;
        !            36:   mp_size_t prec;
        !            37:   mp_exp_t tsize, rexp;
        !            38:   TMP_DECL (marker);
        !            39:
        !            40:   usize = u->_mp_size;
        !            41:   if (usize <= 0)
        !            42:     {
        !            43:       usize = 1 - 1 / (usize == 0);    /* Divide by zero for negative OP.  */
        !            44:       r->_mp_size = usize;     /* cheat flow by using usize here */
        !            45:       r->_mp_exp = 0;
        !            46:       return;
        !            47:     }
        !            48:
        !            49:   TMP_MARK (marker);
        !            50:
        !            51:   prec = r->_mp_prec;
        !            52:   rexp = (u->_mp_exp + 1) >> 1;        /* round towards -inf */
        !            53:   tsize = 2 * prec + (u->_mp_exp & 1);
        !            54:
        !            55:   up = u->_mp_d;
        !            56:   tp = (mp_ptr) TMP_ALLOC (tsize * BYTES_PER_MP_LIMB);
        !            57:
        !            58:   if (usize > tsize)
        !            59:     {
        !            60:       up += usize - tsize;
        !            61:       usize = tsize;
        !            62:       MPN_COPY (tp, up, tsize);
        !            63:     }
        !            64:   else
        !            65:     {
        !            66:       MPN_ZERO (tp, tsize - usize);
        !            67:       MPN_COPY (tp + (tsize - usize), up, usize);
        !            68:     }
        !            69:
        !            70:   mpn_sqrtrem (r->_mp_d, NULL, tp, tsize);
        !            71:
        !            72:   r->_mp_size = (tsize + 1) / 2;
        !            73:   r->_mp_exp = rexp;
        !            74:   TMP_FREE (marker);
        !            75: }