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      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 Dcomplex
     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     Dcomplex z;
     33     COMPLEX_REAL(z) = crt_scalbn((__a * __c + __b * __d) / __denom, -__ilogbw);
     34     COMPLEX_IMAGINARY(z) = crt_scalbn((__b * __c - __a * __d) / __denom, -__ilogbw);
     35     if (crt_isnan(COMPLEX_REAL(z)) && crt_isnan(COMPLEX_IMAGINARY(z)))
     36     {
     37         if ((__denom == 0.0) && (!crt_isnan(__a) || !crt_isnan(__b)))
     38         {
     39             COMPLEX_REAL(z) = crt_copysign(CRT_INFINITY, __c) * __a;
     40             COMPLEX_IMAGINARY(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             COMPLEX_REAL(z) = CRT_INFINITY * (__a * __c + __b * __d);
     48             COMPLEX_IMAGINARY(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             COMPLEX_REAL(z) = 0.0 * (__a * __c + __b * __d);
     56             COMPLEX_IMAGINARY(z) = 0.0 * (__b * __c - __a * __d);
     57         }
     58     }
     59     return z;
     60 }
     61