Annotation of OpenXM_contrib/gmp/mpfr/mul_ui.c, Revision 1.1.1.1
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: }
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