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-rw-r--r--mpfr/mul_ui.c136
1 files changed, 58 insertions, 78 deletions
diff --git a/mpfr/mul_ui.c b/mpfr/mul_ui.c
index e92a79155..c997c41d9 100644
--- a/mpfr/mul_ui.c
+++ b/mpfr/mul_ui.c
@@ -1,20 +1,20 @@
/* mpfr_mul_ui -- multiply a floating-point number by a machine integer
-Copyright (C) 1999 Free Software Foundation.
+Copyright (C) 1999, 2001 Free Software Foundation, Inc.
This file is part of the MPFR Library.
The MPFR Library is free software; you can redistribute it and/or modify
-it under the terms of the GNU Library General Public License as published by
-the Free Software Foundation; either version 2 of the License, or (at your
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version.
The MPFR Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
-or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
+or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.
-You should have received a copy of the GNU Library General Public License
+You should have received a copy of the GNU Lesser General Public License
along with the MPFR Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
@@ -26,26 +26,19 @@ MA 02111-1307, USA. */
#include "mpfr.h"
#include "mpfr-impl.h"
-void
-#if __STDC__
-mpfr_mul_ui(mpfr_ptr y, mpfr_srcptr x, unsigned long int u, mp_rnd_t rnd_mode)
-#else
-mpfr_mul_ui(y, x, u, rnd_mode)
- mpfr_ptr y;
- mpfr_srcptr x;
- unsigned long int u;
- mp_rnd_t rnd_mode;
-#endif
+int
+mpfr_mul_ui (mpfr_ptr y, mpfr_srcptr x, unsigned long int u, mp_rnd_t rnd_mode)
{
- mp_limb_t carry, *my, *old_my, *my2; unsigned long c;
- unsigned long xsize, ysize, cnt, dif, ex, sh;
+ mp_limb_t *my, *old_my;
+ unsigned long xn, yn, cnt, c;
+ int inexact;
TMP_DECL(marker);
if (MPFR_IS_NAN(x))
{
MPFR_CLEAR_FLAGS(y);
MPFR_SET_NAN(y);
- return;
+ return 1; /* a NaN is always inexact */
}
if (MPFR_IS_INF(x))
@@ -54,81 +47,68 @@ mpfr_mul_ui(y, x, u, rnd_mode)
if (u)
{
MPFR_SET_INF(y);
- if (MPFR_SIGN(y) != MPFR_SIGN(x)) { MPFR_CHANGE_SIGN(y); }
- return;
+ if (MPFR_SIGN(y) != MPFR_SIGN(x))
+ MPFR_CHANGE_SIGN(y);
+ return 0; /* infinity is exact */
+ }
+ else /* 0 * infinity */
+ {
+ MPFR_SET_NAN(y);
+ return 1; /* NaN is inexact */
}
- else { MPFR_SET_NAN(y); return; }
}
- MPFR_CLEAR_FLAGS(y);
+ if (MPFR_IS_ZERO(x) || !u)
+ {
+ MPFR_CLEAR_FLAGS(y);
+ MPFR_SET_ZERO(y);
+ return 0; /* zero is exact */
+ }
+
+ MPFR_CLEAR_FLAGS(y);
+
+ if (u == 1)
+ return mpfr_set (y, x, rnd_mode);
TMP_MARK(marker);
- my = MPFR_MANT(y); ex = MPFR_EXP(x);
- ysize = (MPFR_PREC(y)-1)/BITS_PER_MP_LIMB + 1;
- xsize = (MPFR_PREC(x)-1)/BITS_PER_MP_LIMB + 1;
+ my = MPFR_MANT(y);
+ yn = (MPFR_PREC(y) - 1) / BITS_PER_MP_LIMB + 1;
+ xn = (MPFR_PREC(x) - 1) / BITS_PER_MP_LIMB + 1;
- old_my = my;
+ old_my = my;
- if (ysize < xsize) {
- my = (mp_ptr) TMP_ALLOC (xsize * BYTES_PER_MP_LIMB);
- dif=0;
- }
- else dif=ysize-xsize;
+ if (yn < xn + 1)
+ my = (mp_ptr) TMP_ALLOC ((xn + 1) * BYTES_PER_MP_LIMB);
- carry = mpn_mul_1(my+dif, MPFR_MANT(x), xsize, u);
- MPN_ZERO(my, dif);
+ my[xn] = mpn_mul_1 (my, MPFR_MANT(x), xn, u);
+
+ /* x * u is stored in my[xn], ..., my[0] */
- /* WARNING: count_leading_zeros is undefined for carry=0 */
- if (carry) count_leading_zeros(cnt, carry);
- else cnt=BITS_PER_MP_LIMB;
+ /* since the case u=1 was treated above, we have u >= 2, thus
+ my[xn] >= 1 since x was msb-normalized */
+ MPFR_ASSERTN(my[xn] != 0);
+ count_leading_zeros(cnt, my[xn]);
+ mpn_lshift (my, my, xn + 1, cnt);
- /* Warning: the number of limbs used by x and the lower part
- of y may differ */
- sh = (MPFR_PREC(x)+BITS_PER_MP_LIMB-1)/BITS_PER_MP_LIMB
- - (MPFR_PREC(y)+cnt-1)/BITS_PER_MP_LIMB;
+ /* now my[xn], ..., my[0] is msb-normalized too, and has at most
+ PREC(x) + (BITS_PER_MP_LIMB - cnt) non-zero bits */
- /* Warning: if all significant bits are in the carry, one has to
- be careful */
- if (cnt + MPFR_PREC(y) < BITS_PER_MP_LIMB)
- {
- /* Quick 'n dirty */
-
- if (xsize > ysize) {
- my2 = (mp_ptr) TMP_ALLOC ((xsize + 1) * BYTES_PER_MP_LIMB);
- my2[xsize] = mpn_lshift(my2, my, xsize, cnt)
- | (carry << (cnt ? BITS_PER_MP_LIMB - cnt : 0));
- }
- else {
- my2 = (mp_ptr) TMP_ALLOC ((ysize + 1) * BYTES_PER_MP_LIMB);
- my2[ysize] = mpn_lshift(my2, my, ysize, cnt)
- | (carry << (cnt ? BITS_PER_MP_LIMB - cnt : 0));
- }
-
- my = my2; ex += BITS_PER_MP_LIMB - cnt;
- carry = 0; cnt = BITS_PER_MP_LIMB;
- }
+ c = mpfr_round_raw (old_my, my, (xn + 1) * BITS_PER_MP_LIMB,
+ (MPFR_SIGN(x) < 0), MPFR_PREC(y), rnd_mode, &inexact);
- c = mpfr_round_raw(my+sh, my, MPFR_PREC(x), (MPFR_SIGN(x)<0),
- MPFR_PREC(y)-BITS_PER_MP_LIMB+cnt, rnd_mode);
+ MPFR_EXP(y) = MPFR_EXP(x) + BITS_PER_MP_LIMB - cnt;
- /* If cnt = 1111111111111 and c = 1 we shall get depressed */
- if (c && (carry == (((mp_limb_t)1) << (cnt ? BITS_PER_MP_LIMB - cnt : 0))
- - 1))
- {
- cnt--;
- mpn_rshift(my, my, ysize, BITS_PER_MP_LIMB - cnt);
- my[ysize - 1] |= ((mp_limb_t) 1) << (BITS_PER_MP_LIMB - 1);
- }
- else
+ if (c) /* rounded result is 1.0000000000000000... */
{
- /* Warning: mpn_rshift is undefined for shift=0 */
- if (cnt!=BITS_PER_MP_LIMB)
- mpn_rshift(my, my, ysize, BITS_PER_MP_LIMB - cnt);
- my[ysize - 1] |= (carry << cnt);
+ old_my[yn-1] = MP_LIMB_T_HIGHBIT;
+ MPFR_EXP(y) ++;
}
- MPFR_EXP(y) = ex + BITS_PER_MP_LIMB - cnt;
- if (ysize < xsize) MPN_COPY(old_my, my, ysize);
+
/* set sign */
- if (MPFR_SIGN(y) * MPFR_SIGN(x) < 0) MPFR_CHANGE_SIGN(y);
+ if (MPFR_SIGN(y) * MPFR_SIGN(x) < 0)
+ MPFR_CHANGE_SIGN(y);
+
TMP_FREE(marker);
+
+ return inexact;
}
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