| /* Copyright (C) 1995,1996,1997,1998,1999,2002,2003 |
| 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 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 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 |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, write to the Free |
| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. */ |
| |
| #include <float.h> |
| #include <math.h> |
| #include <stdlib.h> |
| #include "gmp-impl.h" |
| |
| /* Convert a `__float128' in IEEE854 quad-precision format to a |
| multi-precision integer representing the significand scaled up by its |
| number of bits (113 for long double) and an integral power of two |
| (MPN frexpl). */ |
| |
| mp_size_t |
| mpn_extract_flt128 (mp_ptr res_ptr, mp_size_t size, |
| int *expt, int *is_neg, |
| __float128 value) |
| { |
| ieee854_float128 u; |
| u.value = value; |
| |
| *is_neg = u.ieee.negative; |
| *expt = (int) u.ieee.exponent - IEEE854_FLOAT128_BIAS; |
| |
| #if BITS_PER_MP_LIMB == 32 |
| res_ptr[0] = u.ieee.mant_low; /* Low-order 32 bits of fraction. */ |
| res_ptr[1] = (u.ieee.mant_low >> 32); |
| res_ptr[2] = u.ieee.mant_high; |
| res_ptr[3] = (u.ieee.mant_high >> 32); /* High-order 32 bits. */ |
| #define N 4 |
| #elif BITS_PER_MP_LIMB == 64 |
| res_ptr[0] = u.ieee.mant_low; |
| res_ptr[1] = u.ieee.mant_high; |
| #define N 2 |
| #else |
| #error "mp_limb size " BITS_PER_MP_LIMB "not accounted for" |
| #endif |
| /* The format does not fill the last limb. There are some zeros. */ |
| #define NUM_LEADING_ZEROS (BITS_PER_MP_LIMB \ |
| - (FLT128_MANT_DIG - ((N - 1) * BITS_PER_MP_LIMB))) |
| |
| 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[1] == 0 |
| && res_ptr[N - 2] == 0 && res_ptr[N - 1] == 0) /* Assumes N<=4. */ |
| /* 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; |
| |
| #if N == 2 |
| if (res_ptr[N - 1] != 0) |
| { |
| count_leading_zeros (cnt, res_ptr[N - 1]); |
| cnt -= NUM_LEADING_ZEROS; |
| res_ptr[N - 1] = res_ptr[N - 1] << cnt |
| | (res_ptr[0] >> (BITS_PER_MP_LIMB - cnt)); |
| res_ptr[0] <<= cnt; |
| *expt = FLT128_MIN_EXP - 1 - cnt; |
| } |
| else |
| { |
| count_leading_zeros (cnt, res_ptr[0]); |
| if (cnt >= NUM_LEADING_ZEROS) |
| { |
| res_ptr[N - 1] = res_ptr[0] << (cnt - NUM_LEADING_ZEROS); |
| res_ptr[0] = 0; |
| } |
| else |
| { |
| res_ptr[N - 1] = res_ptr[0] >> (NUM_LEADING_ZEROS - cnt); |
| res_ptr[0] <<= BITS_PER_MP_LIMB - (NUM_LEADING_ZEROS - cnt); |
| } |
| *expt = FLT128_MIN_EXP - 1 |
| - (BITS_PER_MP_LIMB - NUM_LEADING_ZEROS) - cnt; |
| } |
| #else |
| int j, k, l; |
| |
| for (j = N - 1; j > 0; j--) |
| if (res_ptr[j] != 0) |
| break; |
| |
| count_leading_zeros (cnt, res_ptr[j]); |
| cnt -= NUM_LEADING_ZEROS; |
| l = N - 1 - j; |
| if (cnt < 0) |
| { |
| cnt += BITS_PER_MP_LIMB; |
| l--; |
| } |
| if (!cnt) |
| for (k = N - 1; k >= l; k--) |
| res_ptr[k] = res_ptr[k-l]; |
| else |
| { |
| for (k = N - 1; k > l; k--) |
| res_ptr[k] = res_ptr[k-l] << cnt |
| | res_ptr[k-l-1] >> (BITS_PER_MP_LIMB - cnt); |
| res_ptr[k--] = res_ptr[0] << cnt; |
| } |
| |
| for (; k >= 0; k--) |
| res_ptr[k] = 0; |
| *expt = FLT128_MIN_EXP - 1 - l * BITS_PER_MP_LIMB - cnt; |
| #endif |
| } |
| } |
| else |
| /* Add the implicit leading one bit for a normalized number. */ |
| res_ptr[N - 1] |= (mp_limb_t) 1 << (FLT128_MANT_DIG - 1 |
| - ((N - 1) * BITS_PER_MP_LIMB)); |
| |
| return N; |
| } |