/* Compute complex natural logarithm.
  Copyright (C) 1997-2018 Free Software Foundation, Inc.
  This file is part of the GNU C Library.
  Contributed by Ulrich Drepper <[email protected]>, 1997.

  The GNU C Library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  The GNU C 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
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with the GNU C Library; if not, see
  <http://www.gnu.org/licenses/>.  */

#include "quadmath-imp.h"

__complex128
clogq (__complex128 x)
{
 __complex128 result;
 int rcls = fpclassifyq (__real__ x);
 int icls = fpclassifyq (__imag__ x);

 if (__glibc_unlikely (rcls == QUADFP_ZERO && icls == QUADFP_ZERO))
   {
     /* Real and imaginary part are 0.0.  */
     __imag__ result = signbitq (__real__ x) ? (__float128) M_PIq : 0;
     __imag__ result = copysignq (__imag__ result, __imag__ x);
     /* Yes, the following line raises an exception.  */
     __real__ result = -1 / fabsq (__real__ x);
   }
 else if (__glibc_likely (rcls != QUADFP_NAN && icls != QUADFP_NAN))
   {
     /* Neither real nor imaginary part is NaN.  */
     __float128 absx = fabsq (__real__ x), absy = fabsq (__imag__ x);
     int scale = 0;

     if (absx < absy)
       {
         __float128 t = absx;
         absx = absy;
         absy = t;
       }

     if (absx > FLT128_MAX / 2)
       {
         scale = -1;
         absx = scalbnq (absx, scale);
         absy = (absy >= FLT128_MIN * 2 ? scalbnq (absy, scale) : 0);
       }
     else if (absx < FLT128_MIN && absy < FLT128_MIN)
       {
         scale = FLT128_MANT_DIG;
         absx = scalbnq (absx, scale);
         absy = scalbnq (absy, scale);
       }

     if (absx == 1 && scale == 0)
       {
         __real__ result = log1pq (absy * absy) / 2;
         math_check_force_underflow_nonneg (__real__ result);
       }
     else if (absx > 1 && absx < 2 && absy < 1 && scale == 0)
       {
         __float128 d2m1 = (absx - 1) * (absx + 1);
         if (absy >= FLT128_EPSILON)
           d2m1 += absy * absy;
         __real__ result = log1pq (d2m1) / 2;
       }
     else if (absx < 1
              && absx >= 0.5Q
              && absy < FLT128_EPSILON / 2
              && scale == 0)
       {
         __float128 d2m1 = (absx - 1) * (absx + 1);
         __real__ result = log1pq (d2m1) / 2;
       }
     else if (absx < 1
              && absx >= 0.5Q
              && scale == 0
              && absx * absx + absy * absy >= 0.5Q)
       {
         __float128 d2m1 = __quadmath_x2y2m1q (absx, absy);
         __real__ result = log1pq (d2m1) / 2;
       }
     else
       {
         __float128 d = hypotq (absx, absy);
         __real__ result = logq (d) - scale * (__float128) M_LN2q;
       }

     __imag__ result = atan2q (__imag__ x, __real__ x);
   }
 else
   {
     __imag__ result = nanq ("");
     if (rcls == QUADFP_INFINITE || icls == QUADFP_INFINITE)
       /* Real or imaginary part is infinite.  */
       __real__ result = HUGE_VALQ;
     else
       __real__ result = nanq ("");
   }

 return result;
}