diff options
Diffstat (limited to 'vendor/gmp-6.3.0/mpq/set_f.c')
-rw-r--r-- | vendor/gmp-6.3.0/mpq/set_f.c | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/vendor/gmp-6.3.0/mpq/set_f.c b/vendor/gmp-6.3.0/mpq/set_f.c new file mode 100644 index 0000000..581d4fc --- /dev/null +++ b/vendor/gmp-6.3.0/mpq/set_f.c @@ -0,0 +1,106 @@ +/* mpq_set_f -- set an mpq from an mpf. + +Copyright 2000-2002, 2018 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 either: + + * 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. + +or + + * the GNU General Public License as published by the Free Software + Foundation; either version 2 of the License, or (at your option) any + later version. + +or both in parallel, as here. + +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 General Public License +for more details. + +You should have received copies of the GNU General Public License and the +GNU Lesser General Public License along with the GNU MP Library. If not, +see https://www.gnu.org/licenses/. */ + +#include "gmp-impl.h" +#include "longlong.h" + + +void +mpq_set_f (mpq_ptr q, mpf_srcptr f) +{ + mp_size_t fexp = EXP(f); + mp_ptr fptr = PTR(f); + mp_size_t fsize = SIZ(f); + mp_size_t abs_fsize = ABS(fsize); + mp_limb_t flow; + + if (fsize == 0) + { + /* set q=0 */ + SIZ(NUM(q)) = 0; + SIZ(DEN(q)) = 1; + MPZ_NEWALLOC (DEN(q), 1)[0] = 1; + return; + } + + /* strip low zero limbs from f */ + flow = *fptr; + MPN_STRIP_LOW_ZEROS_NOT_ZERO (fptr, abs_fsize, flow); + + if (fexp >= abs_fsize) + { + /* radix point is to the right of the limbs, no denominator */ + mp_ptr num_ptr; + + num_ptr = MPZ_NEWALLOC (mpq_numref (q), fexp); + MPN_ZERO (num_ptr, fexp - abs_fsize); + MPN_COPY (num_ptr + fexp - abs_fsize, fptr, abs_fsize); + + SIZ(NUM(q)) = fsize >= 0 ? fexp : -fexp; + SIZ(DEN(q)) = 1; + MPZ_NEWALLOC (DEN(q), 1)[0] = 1; + } + else + { + /* radix point is within or to the left of the limbs, use denominator */ + mp_ptr num_ptr, den_ptr; + mp_size_t den_size; + + den_size = abs_fsize - fexp; + num_ptr = MPZ_NEWALLOC (mpq_numref (q), abs_fsize); + den_ptr = MPZ_NEWALLOC (mpq_denref (q), den_size+1); + + if (flow & 1) + { + /* no powers of two to strip from numerator */ + + MPN_COPY (num_ptr, fptr, abs_fsize); + MPN_ZERO (den_ptr, den_size); + den_ptr[den_size] = 1; + } + else + { + /* right shift numerator, adjust denominator accordingly */ + int shift; + + den_size--; + count_trailing_zeros (shift, flow); + + mpn_rshift (num_ptr, fptr, abs_fsize, shift); + abs_fsize -= (num_ptr[abs_fsize-1] == 0); + + MPN_ZERO (den_ptr, den_size); + den_ptr[den_size] = GMP_LIMB_HIGHBIT >> (shift-1); + } + + SIZ(NUM(q)) = fsize >= 0 ? abs_fsize : -abs_fsize; + SIZ(DEN(q)) = den_size + 1; + } +} |