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Annotation of OpenXM_contrib/gmp/mpfr/mul_ui.c, Revision 1.1

1.1     ! maekawa     1: /* mpfr_mul_ui -- multiply a floating-point number by a machine integer
        !             2:
        !             3: Copyright (C) 1999 PolKA project, Inria Lorraine and Loria
        !             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 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 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 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 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 <stdio.h>
        !            23: #include "gmp.h"
        !            24: #include "gmp-impl.h"
        !            25: #include "longlong.h"
        !            26: #include "mpfr.h"
        !            27:
        !            28: void
        !            29: #if __STDC__
        !            30: mpfr_mul_ui(mpfr_ptr y, mpfr_srcptr x, unsigned long u, unsigned char RND_MODE)
        !            31: #else
        !            32: mpfr_mul_ui(y, x, u, RND_MODE)
        !            33:      mpfr_ptr y;
        !            34:      mpfr_srcptr x;
        !            35:      unsigned long u;
        !            36:      unsigned char RND_MODE;
        !            37: #endif
        !            38: {
        !            39:   mp_limb_t carry, *my, *old_my; unsigned long c;
        !            40:   unsigned long xsize, ysize, cnt, dif;
        !            41:   TMP_DECL(marker);
        !            42:
        !            43:   TMP_MARK(marker);
        !            44:   my = MANT(y);
        !            45:   ysize = (PREC(y)-1)/BITS_PER_MP_LIMB + 1;
        !            46:   xsize = (PREC(x)-1)/BITS_PER_MP_LIMB + 1;
        !            47:
        !            48:   if (ysize < xsize) {
        !            49:       old_my = my;
        !            50:       my = (mp_ptr) TMP_ALLOC (xsize * BYTES_PER_MP_LIMB);
        !            51:       dif=0;
        !            52:     }
        !            53:   else dif=ysize-xsize;
        !            54:
        !            55:   carry = mpn_mul_1(my+dif, MANT(x), xsize, u);
        !            56:   MPN_ZERO(my, dif);
        !            57:
        !            58:   /* WARNING: count_leading_zeros is undefined for carry=0 */
        !            59:   if (carry) count_leading_zeros(cnt, carry);
        !            60:   else cnt=BITS_PER_MP_LIMB;
        !            61:
        !            62:   c = mpfr_round_raw(my, my, PREC(x), (SIGN(x)<0),
        !            63:                     PREC(y)-BITS_PER_MP_LIMB+cnt, RND_MODE);
        !            64:
        !            65:   /* If cnt = 1111111111111 and c = 1 we shall get depressed */
        !            66:   if (c && (carry == (((mp_limb_t)1) << (BITS_PER_MP_LIMB - cnt)) - 1))
        !            67:     {
        !            68:       cnt--;
        !            69:       mpn_rshift(my, my, ysize, BITS_PER_MP_LIMB - cnt);
        !            70:       my[ysize - 1] |= ((mp_limb_t) 1) << (BITS_PER_MP_LIMB - 1);
        !            71:     }
        !            72:   else
        !            73:     {
        !            74:       /* Warning: mpn_rshift is undefined for shift=0 */
        !            75:       if (cnt!=BITS_PER_MP_LIMB)
        !            76:        mpn_rshift(my, my, ysize, BITS_PER_MP_LIMB - cnt);
        !            77:       my[ysize - 1] |= (carry << cnt);
        !            78:     }
        !            79:   EXP(y) = EXP(x) + BITS_PER_MP_LIMB - cnt;
        !            80:   if (ysize < xsize) MPN_COPY(old_my, my, ysize);
        !            81:   /* set sign */
        !            82:   if (SIGN(y) != SIGN(x)) CHANGE_SIGN(y);
        !            83:   TMP_FREE(marker);
        !            84: }