Annotation of OpenXM_contrib/gmp/mpfr/add_one_ulp.c, Revision 1.1
1.1 ! ohara 1: /* mpfr_add_one_ulp -- add one unit in last place
! 2:
! 3: Copyright 1999, 2001 Free Software Foundation, Inc.
! 4:
! 5: This file is part of the MPFR Library.
! 6:
! 7: The MPFR 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 MPFR 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 MPFR 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: #include "mpfr.h"
! 25: #include "mpfr-impl.h"
! 26:
! 27: /* sets x to x+sign(x)*ulp(x) */
! 28: int
! 29: mpfr_add_one_ulp (mpfr_ptr x, mp_rnd_t rnd_mode)
! 30: {
! 31: mp_size_t xn;
! 32: int sh;
! 33: mp_limb_t *xp;
! 34:
! 35: if (MPFR_IS_NAN(x))
! 36: MPFR_RET_NAN;
! 37:
! 38: if (MPFR_IS_INF(x) || MPFR_IS_ZERO(x))
! 39: return 0;
! 40:
! 41: xn = 1 + (MPFR_PREC(x) - 1) / BITS_PER_MP_LIMB;
! 42: sh = xn * BITS_PER_MP_LIMB - MPFR_PREC(x);
! 43: xp = MPFR_MANT(x);
! 44: if (mpn_add_1 (xp, xp, xn, MP_LIMB_T_ONE << sh)) /* got 1.0000... */
! 45: {
! 46: mp_exp_t exp = MPFR_EXP(x);
! 47: if (exp == __mpfr_emax)
! 48: return mpfr_set_overflow(x, rnd_mode, MPFR_SIGN(x));
! 49: else
! 50: {
! 51: MPFR_EXP(x)++;
! 52: xp[xn-1] = GMP_LIMB_HIGHBIT;
! 53: }
! 54: }
! 55: return 0;
! 56: }
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