diff options
Diffstat (limited to 'sysdeps')
| -rw-r--r-- | sysdeps/i386/ldbl2mpn.c | 101 | ||||
| -rw-r--r-- | sysdeps/ieee754/ldbl2mpn.c | 7 |
2 files changed, 101 insertions, 7 deletions
diff --git a/sysdeps/i386/ldbl2mpn.c b/sysdeps/i386/ldbl2mpn.c new file mode 100644 index 0000000..8db73cd --- /dev/null +++ b/sysdeps/i386/ldbl2mpn.c @@ -0,0 +1,101 @@ +/* Copyright (C) 1995, 1996 Free Software Foundation, Inc. +This file is part of the GNU C Library. + +The GNU C 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 option) any later version. + +The GNU C 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 License for more details. + +You should have received a copy of the GNU Library General Public +License along with the GNU C Library; see the file COPYING.LIB. If +not, write to the Free Software Foundation, Inc., 675 Mass Ave, +Cambridge, MA 02139, USA. */ + +#include "gmp.h" +#include "gmp-impl.h" +#include "longlong.h" +#include "ieee754.h" +#include <float.h> +#include <stdlib.h> + +/* Convert a `long double' in IEEE854 standard double-precision format to a + multi-precision integer representing the significand scaled up by its + number of bits (64 for long double) and an integral power of two + (MPN frexpl). */ + +mp_size_t +__mpn_extract_long_double (mp_ptr res_ptr, mp_size_t size, + int *expt, int *is_neg, + long double value) +{ + union ieee854_long_double u; + u.d = value; + + *is_neg = u.ieee.negative; + *expt = (int) u.ieee.exponent - IEEE854_LONG_DOUBLE_BIAS; + +#if BITS_PER_MP_LIMB == 32 + res_ptr[0] = u.ieee.mantissa1; /* Low-order 32 bits of fraction. */ + res_ptr[1] = u.ieee.mantissa0; /* High-order 32 bits. */ + #define N 2 +#elif BITS_PER_MP_LIMB == 64 + /* Hopefully the compiler will combine the two bitfield extracts + and this composition into just the original quadword extract. */ + res_ptr[0] = ((unsigned long int) u.ieee.mantissa0 << 32) | u.ieee.mantissa1; + #define N 1 +#else + #error "mp_limb size " BITS_PER_MP_LIMB "not accounted for" +#endif + + if (u.ieee.exponent == 0) + { + /* A biased exponent of zero is a special case. + Either it is a zero or it is a denormal number. */ + if (res_ptr[0] == 0 && res_ptr[N - 1] == 0) /* Assumes N<=2. */ + /* It's zero. */ + *expt = 0; + else + { + /* It is a denormal number, meaning it has no implicit leading + one bit, and its exponent is in fact the format minimum. */ + int cnt; + + /* One problem with Intel's 80-bit format is that the explicit + leading one in the normalized representation has to be zero + for denormalized number. If it is one, the number is according + to Intel's specification an invalid number. We make the + representation unique by explicitly clearing this bit. */ + res_ptr[N - 1] &= ~(1L << ((LDBL_MANT_DIG - 1) % BITS_PER_MP_LIMB)); + + if (res_ptr[N - 1] != 0) + { + count_leading_zeros (cnt, res_ptr[N - 1]); + if (cnt != 0) + { +#if N == 2 + res_ptr[N - 1] = res_ptr[N - 1] << cnt + | (res_ptr[0] >> (BITS_PER_MP_LIMB - cnt)); + res_ptr[0] <<= cnt; +#else + res_ptr[N - 1] <<= cnt; +#endif + } + *expt = LDBL_MIN_EXP - 1 - cnt; + } + else + { + count_leading_zeros (cnt, res_ptr[0]); + res_ptr[N - 1] = res_ptr[0] << cnt; + res_ptr[0] = 0; + *expt = LDBL_MIN_EXP - 1 - BITS_PER_MP_LIMB - cnt; + } + } + } + + return N; +} diff --git a/sysdeps/ieee754/ldbl2mpn.c b/sysdeps/ieee754/ldbl2mpn.c index 8db73cd..b72af2e 100644 --- a/sysdeps/ieee754/ldbl2mpn.c +++ b/sysdeps/ieee754/ldbl2mpn.c @@ -65,13 +65,6 @@ __mpn_extract_long_double (mp_ptr res_ptr, mp_size_t size, one bit, and its exponent is in fact the format minimum. */ int cnt; - /* One problem with Intel's 80-bit format is that the explicit - leading one in the normalized representation has to be zero - for denormalized number. If it is one, the number is according - to Intel's specification an invalid number. We make the - representation unique by explicitly clearing this bit. */ - res_ptr[N - 1] &= ~(1L << ((LDBL_MANT_DIG - 1) % BITS_PER_MP_LIMB)); - if (res_ptr[N - 1] != 0) { count_leading_zeros (cnt, res_ptr[N - 1]); |