1/* mpfr_fmma, mpfr_fmms -- Compute a*b +/- c*d
2
3Copyright 2014-2023 Free Software Foundation, Inc.
4Contributed by the AriC and Caramba projects, INRIA.
5
6This file is part of the GNU MPFR Library.
7
8The GNU MPFR Library is free software; you can redistribute it and/or modify
9it under the terms of the GNU Lesser General Public License as published by
10the Free Software Foundation; either version 3 of the License, or (at your
11option) any later version.
12
13The GNU MPFR Library is distributed in the hope that it will be useful, but
14WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
16License for more details.
17
18You should have received a copy of the GNU Lesser General Public License
19along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
20https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
2151 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
22
23#include "mpfr-impl.h"
24
25/* compute a*b+c*d if neg=0 (fmma), a*b-c*d otherwise (fmms) */
26static int
27mpfr_fmma_aux (mpfr_ptr z, mpfr_srcptr a, mpfr_srcptr b, mpfr_srcptr c,
28               mpfr_srcptr d, mpfr_rnd_t rnd, int neg)
29{
30  mpfr_ubf_t u, v;
31  mpfr_t zz;
32  mpfr_prec_t prec_z = MPFR_PREC(z);
33  mp_size_t un, vn;
34  mpfr_limb_ptr up, vp, zp;
35  int inex;
36  MPFR_TMP_DECL(marker);
37
38  MPFR_LOG_FUNC
39    (("a[%Pu]=%.*Rg b[%Pu]=%.*Rg c[%Pu]=%.*Rg d[%Pu]=%.*Rg rnd=%d neg=%d",
40      mpfr_get_prec (a), mpfr_log_prec, a,
41      mpfr_get_prec (b), mpfr_log_prec, b,
42      mpfr_get_prec (c), mpfr_log_prec, c,
43      mpfr_get_prec (d), mpfr_log_prec, d, rnd, neg),
44     ("z[%Pu]=%.*Rg inex=%d",
45      mpfr_get_prec (z), mpfr_log_prec, z, inex));
46
47  MPFR_TMP_MARK (marker);
48
49  un = MPFR_LIMB_SIZE (a) + MPFR_LIMB_SIZE (b);
50  vn = MPFR_LIMB_SIZE (c) + MPFR_LIMB_SIZE (d);
51  MPFR_TMP_INIT (up, u, (mpfr_prec_t) un * GMP_NUMB_BITS, un);
52  MPFR_TMP_INIT (vp, v, (mpfr_prec_t) vn * GMP_NUMB_BITS, vn);
53
54  mpfr_ubf_mul_exact (u, a, b);
55  mpfr_ubf_mul_exact (v, c, d);
56  if (prec_z == MPFR_PREC(a) && prec_z == MPFR_PREC(b) &&
57      prec_z == MPFR_PREC(c) && prec_z == MPFR_PREC(d) &&
58      un == MPFR_PREC2LIMBS(2 * prec_z))
59    {
60      MPFR_TMP_INIT (zp, zz, 2 * prec_z, un);
61      MPFR_PREC(u) = MPFR_PREC(v) = 2 * prec_z;
62      inex = (neg == 0) ? mpfr_add (zz, (mpfr_srcptr) u, (mpfr_srcptr) v, rnd)
63        : mpfr_sub (zz, (mpfr_srcptr) u, (mpfr_srcptr) v, rnd);
64      inex = mpfr_set_1_2 (z, zz, rnd, inex);
65    }
66  else
67    inex = (neg == 0) ? mpfr_add (z, (mpfr_srcptr) u, (mpfr_srcptr) v, rnd)
68      : mpfr_sub (z, (mpfr_srcptr) u, (mpfr_srcptr) v, rnd);
69
70  MPFR_UBF_CLEAR_EXP (u);
71  MPFR_UBF_CLEAR_EXP (v);
72
73  MPFR_TMP_FREE (marker);
74
75  return inex;
76}
77
78/* z <- a*b + c*d */
79int
80mpfr_fmma (mpfr_ptr z, mpfr_srcptr a, mpfr_srcptr b, mpfr_srcptr c,
81           mpfr_srcptr d, mpfr_rnd_t rnd)
82{
83  return mpfr_fmma_aux (z, a, b, c, d, rnd, 0);
84}
85
86/* z <- a*b - c*d */
87int
88mpfr_fmms (mpfr_ptr z, mpfr_srcptr a, mpfr_srcptr b, mpfr_srcptr c,
89           mpfr_srcptr d, mpfr_rnd_t rnd)
90{
91  return mpfr_fmma_aux (z, a, b, c, d, rnd, 1);
92}
93