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author | Roland McGrath <roland@gnu.org> | 1995-02-18 01:27:10 +0000 |
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committer | Roland McGrath <roland@gnu.org> | 1995-02-18 01:27:10 +0000 |
commit | 28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch) | |
tree | 15f07c4c43d635959c6afee96bde71fb1b3614ee /sysdeps/ieee754/mpn2dbl.c | |
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initial import
Diffstat (limited to 'sysdeps/ieee754/mpn2dbl.c')
-rw-r--r-- | sysdeps/ieee754/mpn2dbl.c | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/sysdeps/ieee754/mpn2dbl.c b/sysdeps/ieee754/mpn2dbl.c new file mode 100644 index 0000000..01e0019 --- /dev/null +++ b/sysdeps/ieee754/mpn2dbl.c @@ -0,0 +1,46 @@ +/* Copyright (C) 1995 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 "ieee754.h" +#include <float.h> + +/* Convert a multi-precision integer of the needed number of bits (53 for + double) and an integral power of two to a `double' in IEEE754 double- + precision format. */ + +double +__mpn_construct_double (mp_srcptr frac_ptr, int expt, int negative) +{ + union ieee754_double u; + + u.ieee.negative = negative; + u.ieee.exponent = expt + IEEE754_DOUBLE_BIAS; +#if BITS_PER_MP_LIMB == 32 + u.ieee.mantissa1 = frac_ptr[0]; + u.ieee.mantissa0 = frac_ptr[1] & ((1 << (DBL_MANT_DIG - 32)) - 1); +#elif BITS_PER_MP_LIMB == 64 + u.ieee.mantissa1 = frac_ptr[0] & ((1 << 32) - 1); + i.ieee.mantissa0 = (frac_ptr[0] >> 32) & ((1 << (DBL_MANT_DIG - 32)) - 1); +#else + #error "mp_limb size " BITS_PER_MP_LIMB "not accounted for" +#endif + + return u.d; +} |