compiler-rt/lib/builtins/divdc3.c

   1 //===-- divdc3.c - Implement __divdc3 -------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements __divdc3 for the compiler_rt library.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #define DOUBLE_PRECISION
  14 #include "fp_lib.h"
  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 __divdc3(double __a, double __b, double __c,
  21                                   double __d) {
  22   int __ilogbw = 0;
  23   double __logbw = __compiler_rt_logb(__compiler_rt_fmax(crt_fabs(__c),
  24                                                          crt_fabs(__d)));
  25   if (crt_isfinite(__logbw)) {
  26     __ilogbw = (int)__logbw;
  27     __c = __compiler_rt_scalbn(__c, -__ilogbw);
  28     __d = __compiler_rt_scalbn(__d, -__ilogbw);
  29   }
  30   double __denom = __c * __c + __d * __d;
  31   Dcomplex z;
  32   COMPLEX_REAL(z) =
  33       __compiler_rt_scalbn((__a * __c + __b * __d) / __denom, -__ilogbw);
  34   COMPLEX_IMAGINARY(z) =
  35       __compiler_rt_scalbn((__b * __c - __a * __d) / __denom, -__ilogbw);
  36   if (crt_isnan(COMPLEX_REAL(z)) && crt_isnan(COMPLEX_IMAGINARY(z))) {
  37     if ((__denom == 0.0) && (!crt_isnan(__a) || !crt_isnan(__b))) {
  38       COMPLEX_REAL(z) = crt_copysign(CRT_INFINITY, __c) * __a;
  39       COMPLEX_IMAGINARY(z) = crt_copysign(CRT_INFINITY, __c) * __b;
  40     } else if ((crt_isinf(__a) || crt_isinf(__b)) && crt_isfinite(__c) &&
  41                crt_isfinite(__d)) {
  42       __a = crt_copysign(crt_isinf(__a) ? 1.0 : 0.0, __a);
  43       __b = crt_copysign(crt_isinf(__b) ? 1.0 : 0.0, __b);
  44       COMPLEX_REAL(z) = CRT_INFINITY * (__a * __c + __b * __d);
  45       COMPLEX_IMAGINARY(z) = CRT_INFINITY * (__b * __c - __a * __d);
  46     } else if (crt_isinf(__logbw) && __logbw > 0.0 && crt_isfinite(__a) &&
  47                crt_isfinite(__b)) {
  48       __c = crt_copysign(crt_isinf(__c) ? 1.0 : 0.0, __c);
  49       __d = crt_copysign(crt_isinf(__d) ? 1.0 : 0.0, __d);
  50       COMPLEX_REAL(z) = 0.0 * (__a * __c + __b * __d);
  51       COMPLEX_IMAGINARY(z) = 0.0 * (__b * __c - __a * __d);
  52     }
  53   }
  54   return z;
  55 }