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Diffstat (limited to 'src/mul_ui.c')
| -rw-r--r-- | src/mul_ui.c | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/src/mul_ui.c b/src/mul_ui.c new file mode 100644 index 0000000..8c9258a --- /dev/null +++ b/src/mul_ui.c @@ -0,0 +1,133 @@ +/* mpfr_mul_ui -- multiply a floating-point number by a machine integer + mpfr_mul_si -- multiply a floating-point number by a machine integer + +Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc. +Contributed by the AriC and Caramel projects, INRIA. + +This file is part of the GNU MPFR Library. + +The GNU MPFR Library is free software; you can redistribute it and/or modify +it under the terms of the GNU Lesser General Public License as published by +the Free Software Foundation; either version 3 of the License, or (at your +option) any later version. + +The GNU 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 Lesser General Public +License for more details. + +You should have received a copy of the GNU Lesser General Public License +along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see +http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., +51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */ + +#define MPFR_NEED_LONGLONG_H +#include "mpfr-impl.h" + +int +mpfr_mul_ui (mpfr_ptr y, mpfr_srcptr x, unsigned long int u, mpfr_rnd_t rnd_mode) +{ + mp_limb_t *yp; + mp_size_t xn; + int cnt, inexact; + MPFR_TMP_DECL (marker); + + if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x))) + { + if (MPFR_IS_NAN (x)) + { + MPFR_SET_NAN (y); + MPFR_RET_NAN; + } + else if (MPFR_IS_INF (x)) + { + if (u != 0) + { + MPFR_SET_INF (y); + MPFR_SET_SAME_SIGN (y, x); + MPFR_RET (0); /* infinity is exact */ + } + else /* 0 * infinity */ + { + MPFR_SET_NAN (y); + MPFR_RET_NAN; + } + } + else /* x is zero */ + { + MPFR_ASSERTD (MPFR_IS_ZERO (x)); + MPFR_SET_ZERO (y); + MPFR_SET_SAME_SIGN (y, x); + MPFR_RET (0); /* zero is exact */ + } + } + else if (MPFR_UNLIKELY (u <= 1)) + { + if (u < 1) + { + MPFR_SET_ZERO (y); + MPFR_SET_SAME_SIGN (y, x); + MPFR_RET (0); /* zero is exact */ + } + else + return mpfr_set (y, x, rnd_mode); + } + else if (MPFR_UNLIKELY (IS_POW2 (u))) + return mpfr_mul_2si (y, x, MPFR_INT_CEIL_LOG2 (u), rnd_mode); + + yp = MPFR_MANT (y); + xn = MPFR_LIMB_SIZE (x); + + MPFR_ASSERTD (xn < MP_SIZE_T_MAX); + MPFR_TMP_MARK(marker); + yp = MPFR_TMP_LIMBS_ALLOC (xn + 1); + + MPFR_ASSERTN (u == (mp_limb_t) u); + yp[xn] = mpn_mul_1 (yp, MPFR_MANT (x), xn, u); + + /* x * u is stored in yp[xn], ..., yp[0] */ + + /* since the case u=1 was treated above, we have u >= 2, thus + yp[xn] >= 1 since x was msb-normalized */ + MPFR_ASSERTD (yp[xn] != 0); + if (MPFR_LIKELY (MPFR_LIMB_MSB (yp[xn]) == 0)) + { + count_leading_zeros (cnt, yp[xn]); + mpn_lshift (yp, yp, xn + 1, cnt); + } + else + { + cnt = 0; + } + + /* now yp[xn], ..., yp[0] is msb-normalized too, and has at most + PREC(x) + (GMP_NUMB_BITS - cnt) non-zero bits */ + MPFR_RNDRAW (inexact, y, yp, (mpfr_prec_t) (xn + 1) * GMP_NUMB_BITS, + rnd_mode, MPFR_SIGN (x), cnt -- ); + + MPFR_TMP_FREE (marker); + + cnt = GMP_NUMB_BITS - cnt; + if (MPFR_UNLIKELY (__gmpfr_emax < MPFR_EMAX_MIN + cnt + || MPFR_GET_EXP (x) > __gmpfr_emax - cnt)) + return mpfr_overflow (y, rnd_mode, MPFR_SIGN(x)); + + MPFR_SET_EXP (y, MPFR_GET_EXP (x) + cnt); + MPFR_SET_SAME_SIGN (y, x); + + return inexact; +} + +int mpfr_mul_si (mpfr_ptr y, mpfr_srcptr x, long int u, mpfr_rnd_t rnd_mode) +{ + int res; + + if (u >= 0) + res = mpfr_mul_ui (y, x, u, rnd_mode); + else + { + res = -mpfr_mul_ui (y, x, -u, MPFR_INVERT_RND (rnd_mode)); + MPFR_CHANGE_SIGN (y); + } + return res; +} |