diff options
Diffstat (limited to 'gnu/lib/libgmp/mpf/set_prc.c')
-rw-r--r-- | gnu/lib/libgmp/mpf/set_prc.c | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/gnu/lib/libgmp/mpf/set_prc.c b/gnu/lib/libgmp/mpf/set_prc.c new file mode 100644 index 0000000..10f2b06 --- /dev/null +++ b/gnu/lib/libgmp/mpf/set_prc.c @@ -0,0 +1,57 @@ +/* mpf_set_prec(x) -- Change the precision of x. + +Copyright (C) 1993, 1994, 1995 Free Software Foundation, Inc. + +This file is part of the GNU MP Library. + +The GNU MP 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 MP 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 MP 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. */ + +#include "gmp.h" +#include "gmp-impl.h" + +void +#if __STDC__ +mpf_set_prec (mpf_ptr x, unsigned long int prec_in_bits) +#else +mpf_set_prec (x, prec_in_bits) + mpf_ptr x; + unsigned long int prec_in_bits; +#endif +{ + mp_size_t prec; + mp_size_t size = ABS (x->_mp_size); + + prec = (MAX (53, prec_in_bits) + 2 * BITS_PER_MP_LIMB - 1)/BITS_PER_MP_LIMB; + + /* We want the most significant limbs, so move the limbs down if we are + about to truncate the value. */ + if (size > prec + 1) + { + mp_size_t offset = size - (prec + 1); + mp_ptr xp = x->_mp_d; + + MPN_COPY (xp, xp + offset, prec + 1); + } + + x->_mp_d = (mp_ptr) (*_mp_reallocate_func) + (x->_mp_d, + (x->_mp_prec + 1) * BYTES_PER_MP_LIMB, (prec + 1) * BYTES_PER_MP_LIMB); + x->_mp_prec = prec; + + /* If the precision decreased, truncate the number. */ + if (size > prec + 1) + x->_mp_size = x->_mp_size >= 0 ? (prec + 1) : -(prec + 1); +} |