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Diffstat (limited to 'contrib/libgmp/mpf/add.c')
| -rw-r--r-- | contrib/libgmp/mpf/add.c | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/contrib/libgmp/mpf/add.c b/contrib/libgmp/mpf/add.c new file mode 100644 index 000000000000..2db876fc657f --- /dev/null +++ b/contrib/libgmp/mpf/add.c @@ -0,0 +1,180 @@ +/* mpf_add -- Add two floats. + +Copyright (C) 1993, 1994, 1996 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_add (mpf_ptr r, mpf_srcptr u, mpf_srcptr v) +#else +mpf_add (r, u, v) + mpf_ptr r; + mpf_srcptr u; + mpf_srcptr v; +#endif +{ + mp_srcptr up, vp; + mp_ptr rp, tp; + mp_size_t usize, vsize, rsize; + mp_size_t prec; + mp_exp_t uexp; + mp_size_t ediff; + mp_limb_t cy; + int negate; + TMP_DECL (marker); + + usize = u->_mp_size; + vsize = v->_mp_size; + + /* Handle special cases that don't work in generic code below. */ + if (usize == 0) + { + mpf_set (r, v); + return; + } + if (vsize == 0) + { + mpf_set (r, u); + return; + } + + /* If signs of U and V are different, perform subtraction. */ + if ((usize ^ vsize) < 0) + { + __mpf_struct v_negated; + v_negated._mp_size = -vsize; + v_negated._mp_exp = v->_mp_exp; + v_negated._mp_d = v->_mp_d; + mpf_sub (r, u, &v_negated); + return; + } + + TMP_MARK (marker); + + /* Signs are now known to be the same. */ + negate = usize < 0; + + /* Make U be the operand with the largest exponent. */ + if (u->_mp_exp < v->_mp_exp) + { + mpf_srcptr t; + t = u; u = v; v = t; + usize = u->_mp_size; + vsize = v->_mp_size; + } + + usize = ABS (usize); + vsize = ABS (vsize); + up = u->_mp_d; + vp = v->_mp_d; + rp = r->_mp_d; + prec = r->_mp_prec; + uexp = u->_mp_exp; + ediff = u->_mp_exp - v->_mp_exp; + + /* If U extends beyond PREC, ignore the part that does. */ + if (usize > prec) + { + up += usize - prec; + usize = prec; + } + + /* If V extends beyond PREC, ignore the part that does. + Note that this may make vsize negative. */ + if (vsize + ediff > prec) + { + vp += vsize + ediff - prec; + vsize = prec - ediff; + } + +#if 0 + /* Locate the least significant non-zero limb in (the needed parts + of) U and V, to simplify the code below. */ + while (up[0] == 0) + up++, usize--; + while (vp[0] == 0) + vp++, vsize--; +#endif + + /* Allocate temp space for the result. Allocate + just vsize + ediff later??? */ + tp = (mp_ptr) TMP_ALLOC (prec * BYTES_PER_MP_LIMB); + + if (ediff >= prec) + { + /* V completely cancelled. */ + if (tp != up) + MPN_COPY (rp, up, usize); + rsize = usize; + } + else + { + /* uuuu | uuuu | uuuu | uuuu | uuuu */ + /* vvvvvvv | vv | vvvvv | v | vv */ + + if (usize > ediff) + { + /* U and V partially overlaps. */ + if (vsize + ediff <= usize) + { + /* uuuu */ + /* v */ + mp_size_t size; + size = usize - ediff - vsize; + MPN_COPY (tp, up, size); + cy = mpn_add (tp + size, up + size, usize - size, vp, vsize); + rsize = usize; + } + else + { + /* uuuu */ + /* vvvvv */ + mp_size_t size; + size = vsize + ediff - usize; + MPN_COPY (tp, vp, size); + cy = mpn_add (tp + size, up, usize, vp + size, usize - ediff); + rsize = vsize + ediff; + } + } + else + { + /* uuuu */ + /* vv */ + mp_size_t size; + size = vsize + ediff - usize; + MPN_COPY (tp, vp, vsize); + MPN_ZERO (tp + vsize, ediff - usize); + MPN_COPY (tp + size, up, usize); + cy = 0; + rsize = size + usize; + } + + MPN_COPY (rp, tp, rsize); + rp[rsize] = cy; + rsize += cy; + uexp += cy; + } + + r->_mp_size = negate ? -rsize : rsize; + r->_mp_exp = uexp; + TMP_FREE (marker); +} |