libgcc/config/rs6000/_divkc3.c

   1 /* Copyright (C) 1989-2019 Free Software Foundation, Inc.
   2
   3 This file is part of GCC.
   4
   5 GCC is free software; you can redistribute it and/or modify it under
   6 the terms of the GNU General Public License as published by the Free
   7 Software Foundation; either version 3, or (at your option) any later
   8 version.
   9
  10 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  11 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13 for more details.
  14
  15 Under Section 7 of GPL version 3, you are granted additional
  16 permissions described in the GCC Runtime Library Exception, version
  17 3.1, as published by the Free Software Foundation.
  18
  19 You should have received a copy of the GNU General Public License and
  20 a copy of the GCC Runtime Library Exception along with this program;
  21 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  22 <http://www.gnu.org/licenses/>.  */
  23
  24 /* This is a temporary specialization of code from libgcc/libgcc2.c.  */
  25
  26 #include "soft-fp.h"
  27 #include "quad-float128.h"
  28
  29 #define COPYSIGN(x,y) __builtin_copysignf128 (x, y)
  30 #define INFINITY __builtin_inff128 ()
  31 #define FABS __builtin_fabsf128
  32 #define isnan __builtin_isnan
  33 #define isinf __builtin_isinf
  34 #define isfinite __builtin_isfinite
  35
  36 #if defined(FLOAT128_HW_INSNS) && !defined(__divkc3)
  37 #define __divkc3 __divkc3_sw
  38 #endif
  39
  40 TCtype
  41 __divkc3 (TFtype a, TFtype b, TFtype c, TFtype d)
  42 {
  43   TFtype denom, ratio, x, y;
  44   TCtype res;
  45
  46   /* ??? We can get better behavior from logarithmic scaling instead of
  47      the division.  But that would mean starting to link libgcc against
  48      libm.  We could implement something akin to ldexp/frexp as gcc builtins
  49      fairly easily...  */
  50   if (FABS (c) < FABS (d))
  51     {
  52       ratio = c / d;
  53       denom = (c * ratio) + d;
  54       x = ((a * ratio) + b) / denom;
  55       y = ((b * ratio) - a) / denom;
  56     }
  57   else
  58     {
  59       ratio = d / c;
  60       denom = (d * ratio) + c;
  61       x = ((b * ratio) + a) / denom;
  62       y = (b - (a * ratio)) / denom;
  63     }
  64
  65   /* Recover infinities and zeros that computed as NaN+iNaN; the only cases
  66      are nonzero/zero, infinite/finite, and finite/infinite.  */
  67   if (isnan (x) && isnan (y))
  68     {
  69       if (c == 0.0 && d == 0.0 && (!isnan (a) || !isnan (b)))
  70         {
  71           x = COPYSIGN (INFINITY, c) * a;
  72           y = COPYSIGN (INFINITY, c) * b;
  73         }
  74       else if ((isinf (a) || isinf (b)) && isfinite (c) && isfinite (d))
  75         {
  76           a = COPYSIGN (isinf (a) ? 1 : 0, a);
  77           b = COPYSIGN (isinf (b) ? 1 : 0, b);
  78           x = INFINITY * (a * c + b * d);
  79           y = INFINITY * (b * c - a * d);
  80         }
  81       else if ((isinf (c) || isinf (d)) && isfinite (a) && isfinite (b))
  82         {
  83           c = COPYSIGN (isinf (c) ? 1 : 0, c);
  84           d = COPYSIGN (isinf (d) ? 1 : 0, d);
  85           x = 0.0 * (a * c + b * d);
  86           y = 0.0 * (b * c - a * d);
  87         }
  88     }
  89
  90   __real__ res = x;
  91   __imag__ res = y;
  92   return res;
  93 }