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

1.1     ! ohara       1: /* mpf_ceil, mpf_floor -- round an mpf to an integer.
        !             2:
        !             3: Copyright 2001 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 Lesser General Public License as published by
        !             9: the Free Software Foundation; either version 2.1 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 Lesser General Public
        !            15: License for more details.
        !            16:
        !            17: You should have received a copy of the GNU Lesser 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:
        !            26: /* dir==1 for ceil, dir==-1 for floor
        !            27:
        !            28:    Notice the use of prec+1 ensures mpf_ceil and mpf_floor are equivalent to
        !            29:    mpf_set if u is already an integer.  */
        !            30:
        !            31: static void __gmpf_ceil_or_floor _PROTO ((REGPARM_2_1 (mpf_ptr r, mpf_srcptr u, int dir))) REGPARM_ATTR (1);
        !            32: #define mpf_ceil_or_floor(r,u,dir)  __gmpf_ceil_or_floor (REGPARM_2_1 (r, u, dir))
        !            33:
        !            34: static void
        !            35: mpf_ceil_or_floor (mpf_ptr r, mpf_srcptr u, int dir)
        !            36: {
        !            37:   mp_ptr     rp, up, p;
        !            38:   mp_size_t  size, asize, prec;
        !            39:   mp_exp_t   exp;
        !            40:
        !            41:   size = SIZ(u);
        !            42:   if (size == 0)
        !            43:     {
        !            44:     zero:
        !            45:       SIZ(r) = 0;
        !            46:       EXP(r) = 0;
        !            47:       return;
        !            48:     }
        !            49:
        !            50:   rp = PTR(r);
        !            51:   exp = EXP(u);
        !            52:   if (exp <= 0)
        !            53:     {
        !            54:       /* u is only a fraction */
        !            55:       if ((size ^ dir) < 0)
        !            56:         goto zero;
        !            57:       rp[0] = 1;
        !            58:       EXP(r) = 1;
        !            59:       SIZ(r) = dir;
        !            60:       return;
        !            61:     }
        !            62:   EXP(r) = exp;
        !            63:
        !            64:   up = PTR(u);
        !            65:   asize = ABS (size);
        !            66:   up += asize;
        !            67:
        !            68:   /* skip fraction part of u */
        !            69:   asize = MIN (asize, exp);
        !            70:
        !            71:   /* don't lose precision in the copy */
        !            72:   prec = PREC (r) + 1;
        !            73:
        !            74:   /* skip excess over target precision */
        !            75:   asize = MIN (asize, prec);
        !            76:
        !            77:   up -= asize;
        !            78:
        !            79:   if ((size ^ dir) >= 0)
        !            80:     {
        !            81:       /* rounding direction matches sign, must increment if ignored part is
        !            82:          non-zero */
        !            83:       for (p = PTR(u); p != up; p++)
        !            84:         {
        !            85:           if (*p != 0)
        !            86:             {
        !            87:               if (mpn_add_1 (rp, up, asize, CNST_LIMB(1)))
        !            88:                 {
        !            89:                   /* was all 0xFF..FFs, which have become zeros, giving just
        !            90:                      a carry */
        !            91:                   rp[0] = 1;
        !            92:                   asize = 1;
        !            93:                   EXP(r)++;
        !            94:                 }
        !            95:               SIZ(r) = (size >= 0 ? asize : -asize);
        !            96:               return;
        !            97:             }
        !            98:         }
        !            99:     }
        !           100:
        !           101:   SIZ(r) = (size >= 0 ? asize : -asize);
        !           102:   if (rp != up)
        !           103:     MPN_COPY_INCR (rp, up, asize);
        !           104: }
        !           105:
        !           106:
        !           107: void
        !           108: mpf_ceil (mpf_ptr r, mpf_srcptr u)
        !           109: {
        !           110:   mpf_ceil_or_floor (r, u, 1);
        !           111: }
        !           112:
        !           113: void
        !           114: mpf_floor (mpf_ptr r, mpf_srcptr u)
        !           115: {
        !           116:   mpf_ceil_or_floor (r, u, -1);
        !           117: }