1: /* Copyright (C) 2005, 2006 Free Software Foundation, Inc.
    2:    This file is part of the GNU C Library.
    3:    Contributed by Richard Henderson <rth@redhat.com>, 2005.
    4: 
    5:    The GNU C Library is free software; you can redistribute it and/or
    6:    modify it under the terms of the GNU Lesser General Public
    7:    License as published by the Free Software Foundation; either
    8:    version 2.1 of the License, or (at your option) any later version.
    9: 
   10:    The GNU C Library is distributed in the hope that it will be useful,
   11:    but WITHOUT ANY WARRANTY; without even the implied warranty of
   12:    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   13:    Lesser General Public License for more details.
   14: 
   15:    You should have received a copy of the GNU Lesser General Public
   16:    License along with the GNU C Library; if not, write to the Free
   17:    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   18:    02111-1307 USA.  */
   19: 
   20: #include <stdbool.h>
   21: #include <math.h>
   22: #include <complex.h>
   23: 
   24: attribute_hidden
   25: long double _Complex
   26: __multc3 (long double a, long double b, long double c, long double d)
   27: {
   28:   long double ac, bd, ad, bc, x, y;
   29: 
   30:   ac = a * c;
   31:   bd = b * d;
   32:   ad = a * d;
   33:   bc = b * c;
   34: 
   35:   x = ac - bd;
   36:   y = ad + bc;
   37: 
   38:   if (isnan (x) && isnan (y))
   39:     {
   40:       /* Recover infinities that computed as NaN + iNaN.  */
   41:       bool recalc = 0;
   42:       if (isinf (a) || isinf (b))
   43:         {
   44:           /* z is infinite.  "Box" the infinity and change NaNs in
   45:              the other factor to 0.  */
   46:           a = __copysignl (isinf (a) ? 1 : 0, a);
   47:           b = __copysignl (isinf (b) ? 1 : 0, b);
   48:           if (isnan (c)) c = __copysignl (0, c);
   49:           if (isnan (d)) d = __copysignl (0, d);
   50:           recalc = 1;
   51:         }
   52:      if (isinf (c) || isinf (d))
   53:         {
   54:           /* w is infinite.  "Box" the infinity and change NaNs in
   55:              the other factor to 0.  */
   56:           c = __copysignl (isinf (c) ? 1 : 0, c);
   57:           d = __copysignl (isinf (d) ? 1 : 0, d);
   58:           if (isnan (a)) a = __copysignl (0, a);
   59:           if (isnan (b)) b = __copysignl (0, b);
   60:           recalc = 1;
   61:         }
   62:      if (!recalc
   63:           && (isinf (ac) || isinf (bd) || isinf (ad) || isinf (bc)))
   64:         {
   65:           /* Recover infinities from overflow by changing NaNs to 0.  */
   66:           if (isnan (a)) a = __copysignl (0, a);
   67:           if (isnan (b)) b = __copysignl (0, b);
   68:           if (isnan (c)) c = __copysignl (0, c);
   69:           if (isnan (d)) d = __copysignl (0, d);
   70:           recalc = 1;
   71:         }
   72:       if (recalc)
   73:         {
   74:           x = INFINITY * (a * c - b * d);
   75:           y = INFINITY * (a * d + b * c);
   76:         }
   77:     }
   78: 
   79:   return x + I * y;
   80: }