lib/builtins/divdc3.c

   1 /* ===-- divdc3.c - Implement __divdc3 -------------------------------------===
   2  *
   3  *                     The LLVM Compiler Infrastructure
   4  *
   5  * This file is dual licensed under the MIT and the University of Illinois Open
   6  * Source Licenses. See LICENSE.TXT for details.
   7  *
   8  * ===----------------------------------------------------------------------===
   9  *
  10  * This file implements __divdc3 for the compiler_rt library.
  11  *
  12  * ===----------------------------------------------------------------------===
  13  */
  14
  15 #include "int_lib.h"
  16 #include "int_math.h"
  17
  18 /* Returns: the quotient of (a + ib) / (c + id) */
  19
  20 COMPILER_RT_ABI double _Complex
  21 __divdc3(double __a, double __b, double __c, double __d)
  22 {
  23     int __ilogbw = 0;
  24     double __logbw = crt_logb(crt_fmax(crt_fabs(__c), crt_fabs(__d)));
  25     if (crt_isfinite(__logbw))
  26     {
  27         __ilogbw = (int)__logbw;
  28         __c = crt_scalbn(__c, -__ilogbw);
  29         __d = crt_scalbn(__d, -__ilogbw);
  30     }
  31     double __denom = __c * __c + __d * __d;
  32     double _Complex z;
  33     __real__ z = crt_scalbn((__a * __c + __b * __d) / __denom, -__ilogbw);
  34     __imag__ z = crt_scalbn((__b * __c - __a * __d) / __denom, -__ilogbw);
  35     if (crt_isnan(__real__ z) && crt_isnan(__imag__ z))
  36     {
  37         if ((__denom == 0.0) && (!crt_isnan(__a) || !crt_isnan(__b)))
  38         {
  39             __real__ z = crt_copysign(CRT_INFINITY, __c) * __a;
  40             __imag__ z = crt_copysign(CRT_INFINITY, __c) * __b;
  41         }
  42         else if ((crt_isinf(__a) || crt_isinf(__b)) &&
  43                  crt_isfinite(__c) && crt_isfinite(__d))
  44         {
  45             __a = crt_copysign(crt_isinf(__a) ? 1.0 : 0.0, __a);
  46             __b = crt_copysign(crt_isinf(__b) ? 1.0 : 0.0, __b);
  47             __real__ z = CRT_INFINITY * (__a * __c + __b * __d);
  48             __imag__ z = CRT_INFINITY * (__b * __c - __a * __d);
  49         }
  50         else if (crt_isinf(__logbw) && __logbw > 0.0 &&
  51                  crt_isfinite(__a) && crt_isfinite(__b))
  52         {
  53             __c = crt_copysign(crt_isinf(__c) ? 1.0 : 0.0, __c);
  54             __d = crt_copysign(crt_isinf(__d) ? 1.0 : 0.0, __d);
  55             __real__ z = 0.0 * (__a * __c + __b * __d);
  56             __imag__ z = 0.0 * (__b * __c - __a * __d);
  57         }
  58     }
  59     return z;
  60 }