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Annotation of OpenXM_contrib/gmp/mpf/ceilfloor.c, Revision 1.1.1.1

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: }