From 11da511c784eca003deb90c23570f0873954e0de Mon Sep 17 00:00:00 2001 From: Duncan Wilkie Date: Sat, 18 Nov 2023 06:11:09 -0600 Subject: Initial commit. --- gmp-6.3.0/mpf/div.c | 137 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 137 insertions(+) create mode 100644 gmp-6.3.0/mpf/div.c (limited to 'gmp-6.3.0/mpf/div.c') diff --git a/gmp-6.3.0/mpf/div.c b/gmp-6.3.0/mpf/div.c new file mode 100644 index 0000000..d13af75 --- /dev/null +++ b/gmp-6.3.0/mpf/div.c @@ -0,0 +1,137 @@ +/* mpf_div -- Divide two floats. + +Copyright 1993, 1994, 1996, 2000-2002, 2004, 2005, 2010, 2012 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" + + +/* Not done: + + No attempt is made to identify an overlap u==v. The result will be + correct (1.0), but a full actual division is done whereas of course + x/x==1 needs no work. Such a call is not a sensible thing to make, and + it's left to an application to notice and optimize if it might arise + somehow through pointer aliasing or whatever. + + Enhancements: + + The high quotient limb is non-zero when high{up,vsize} >= {vp,vsize}. We + could make that comparison and use qsize==prec instead of qsize==prec+1, + to save one limb in the division. + + If r==u but the size is enough bigger than prec that there won't be an + overlap between quotient and dividend in mpn_div_q, then we can avoid + copying up,usize. This would only arise from a prec reduced with + mpf_set_prec_raw and will be pretty unusual, but might be worthwhile if + it could be worked into the copy_u decision cleanly. */ + +void +mpf_div (mpf_ptr r, mpf_srcptr u, mpf_srcptr v) +{ + mp_srcptr up, vp; + mp_ptr rp, tp, new_vp; + mp_size_t usize, vsize, rsize, prospective_rsize, tsize, zeros; + mp_size_t sign_quotient, prec, high_zero, chop; + mp_exp_t rexp; + int copy_u; + TMP_DECL; + + usize = SIZ(u); + vsize = SIZ(v); + + if (UNLIKELY (vsize == 0)) + DIVIDE_BY_ZERO; + + if (usize == 0) + { + SIZ(r) = 0; + EXP(r) = 0; + return; + } + + sign_quotient = usize ^ vsize; + usize = ABS (usize); + vsize = ABS (vsize); + prec = PREC(r); + + TMP_MARK; + rexp = EXP(u) - EXP(v) + 1; + + rp = PTR(r); + up = PTR(u); + vp = PTR(v); + + prospective_rsize = usize - vsize + 1; /* quot from using given u,v sizes */ + rsize = prec + 1; /* desired quot */ + + zeros = rsize - prospective_rsize; /* padding u to give rsize */ + copy_u = (zeros > 0 || rp == up); /* copy u if overlap or padding */ + + chop = MAX (-zeros, 0); /* negative zeros means shorten u */ + up += chop; + usize -= chop; + zeros += chop; /* now zeros >= 0 */ + + tsize = usize + zeros; /* size for possible copy of u */ + + /* copy and possibly extend u if necessary */ + if (copy_u) + { + tp = TMP_ALLOC_LIMBS (tsize + 1); /* +1 for mpn_div_q's scratch needs */ + MPN_ZERO (tp, zeros); + MPN_COPY (tp+zeros, up, usize); + up = tp; + usize = tsize; + } + else + { + tp = TMP_ALLOC_LIMBS (usize + 1); + } + + /* ensure divisor doesn't overlap quotient */ + if (rp == vp) + { + new_vp = TMP_ALLOC_LIMBS (vsize); + MPN_COPY (new_vp, vp, vsize); + vp = new_vp; + } + + ASSERT (usize-vsize+1 == rsize); + mpn_div_q (rp, up, usize, vp, vsize, tp); + + /* strip possible zero high limb */ + high_zero = (rp[rsize-1] == 0); + rsize -= high_zero; + rexp -= high_zero; + + SIZ(r) = sign_quotient >= 0 ? rsize : -rsize; + EXP(r) = rexp; + TMP_FREE; +} -- cgit v1.2.3