llvm-project/compiler-rt/lib/builtins/muldc3.c

//===-- muldc3.c - Implement __muldc3 -------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements __muldc3 for the compiler_rt library.
//
//===----------------------------------------------------------------------===//

#include "int_lib.h"
#include "int_math.h"

// Returns: the product of a + ib and c + id

COMPILER_RT_ABI Dcomplex __muldc3(double __a, double __b, double __c,
                                  double __d) {
  double __ac = __a * __c;
  double __bd = __b * __d;
  double __ad = __a * __d;
  double __bc = __b * __c;
  Dcomplex z;
  COMPLEX_REAL(z) = __ac - __bd;
  COMPLEX_IMAGINARY(z) = __ad + __bc;
  if (crt_isnan(COMPLEX_REAL(z)) && crt_isnan(COMPLEX_IMAGINARY(z))) {
    int __recalc = 0;
    if (crt_isinf(__a) || crt_isinf(__b)) {
      __a = crt_copysign(crt_isinf(__a) ? 1 : 0, __a);
      __b = crt_copysign(crt_isinf(__b) ? 1 : 0, __b);
      if (crt_isnan(__c))
        __c = crt_copysign(0, __c);
      if (crt_isnan(__d))
        __d = crt_copysign(0, __d);
      __recalc = 1;
    }
    if (crt_isinf(__c) || crt_isinf(__d)) {
      __c = crt_copysign(crt_isinf(__c) ? 1 : 0, __c);
      __d = crt_copysign(crt_isinf(__d) ? 1 : 0, __d);
      if (crt_isnan(__a))
        __a = crt_copysign(0, __a);
      if (crt_isnan(__b))
        __b = crt_copysign(0, __b);
      __recalc = 1;
    }
    if (!__recalc && (crt_isinf(__ac) || crt_isinf(__bd) || crt_isinf(__ad) ||
                      crt_isinf(__bc))) {
      if (crt_isnan(__a))
        __a = crt_copysign(0, __a);
      if (crt_isnan(__b))
        __b = crt_copysign(0, __b);
      if (crt_isnan(__c))
        __c = crt_copysign(0, __c);
      if (crt_isnan(__d))
        __d = crt_copysign(0, __d);
      __recalc = 1;
    }
    if (__recalc) {
      COMPLEX_REAL(z) = CRT_INFINITY * (__a * __c - __b * __d);
      COMPLEX_IMAGINARY(z) = CRT_INFINITY * (__a * __d + __b * __c);
    }
  }
  return z;
}