compiler-rt/lib/builtins/ppc/multc3.c

// 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

#include "../int_math.h"
#include "DD.h"

#define makeFinite(x)                                                          \
  {                                                                            \
    (x).s.hi = crt_copysign(crt_isinf((x).s.hi) ? 1.0 : 0.0, (x).s.hi);        \
    (x).s.lo = 0.0;                                                            \
  }

#define zeroNaN(x)                                                             \
  {                                                                            \
    if (crt_isnan((x).s.hi)) {                                                 \
      (x).s.hi = crt_copysign(0.0, (x).s.hi);                                  \
      (x).s.lo = 0.0;                                                          \
    }                                                                          \
  }

long double _Complex __multc3(long double a, long double b, long double c,
                              long double d) {
  long double ac = __gcc_qmul(a, c);
  long double bd = __gcc_qmul(b, d);
  long double ad = __gcc_qmul(a, d);
  long double bc = __gcc_qmul(b, c);

  DD real = {.ld = __gcc_qsub(ac, bd)};
  DD imag = {.ld = __gcc_qadd(ad, bc)};

  if (crt_isnan(real.s.hi) && crt_isnan(imag.s.hi)) {
    int recalc = 0;

    DD aDD = {.ld = a};
    DD bDD = {.ld = b};
    DD cDD = {.ld = c};
    DD dDD = {.ld = d};

    if (crt_isinf(aDD.s.hi) || crt_isinf(bDD.s.hi)) {
      makeFinite(aDD);
      makeFinite(bDD);
      zeroNaN(cDD);
      zeroNaN(dDD);
      recalc = 1;
    }

    if (crt_isinf(cDD.s.hi) || crt_isinf(dDD.s.hi)) {
      makeFinite(cDD);
      makeFinite(dDD);
      zeroNaN(aDD);
      zeroNaN(bDD);
      recalc = 1;
    }

    if (!recalc) {
      DD acDD = {.ld = ac};
      DD bdDD = {.ld = bd};
      DD adDD = {.ld = ad};
      DD bcDD = {.ld = bc};

      if (crt_isinf(acDD.s.hi) || crt_isinf(bdDD.s.hi) ||
          crt_isinf(adDD.s.hi) || crt_isinf(bcDD.s.hi)) {
        zeroNaN(aDD);
        zeroNaN(bDD);
        zeroNaN(cDD);
        zeroNaN(dDD);
        recalc = 1;
      }
    }

    if (recalc) {
      real.s.hi = CRT_INFINITY * (aDD.s.hi * cDD.s.hi - bDD.s.hi * dDD.s.hi);
      real.s.lo = 0.0;
      imag.s.hi = CRT_INFINITY * (aDD.s.hi * dDD.s.hi + bDD.s.hi * cDD.s.hi);
      imag.s.lo = 0.0;
    }
  }

  long double _Complex z;
  __real__ z = real.ld;
  __imag__ z = imag.ld;

  return z;
}