/*

 * Copyright (c) 2005-2020 Rich Felker, et al.

 *

 * SPDX-License-Identifier: MIT

 *

 * Please see https://git.musl-libc.org/cgit/musl/tree/COPYRIGHT

 * for all contributors to musl.

 */

#include "math_private.h"

double s_scalbn(double x, int n)

{

  union {double f; uint64_t i;} u;

  double_t y = x;

  if (n > 1023) {

    y *= 0x1p1023;

    n -= 1023;

    if (n > 1023) {

      y *= 0x1p1023;

      n -= 1023;

      if (n > 1023)

        n = 1023;

    }

  } else if (n < -1022) {

    /* make sure final n < -53 to avoid double

       rounding in the subnormal range */

    y *= 0x1p-1022 * 0x1p53;

    n += 1022 - 53;

    if (n < -1022) {

      y *= 0x1p-1022 * 0x1p53;

      n += 1022 - 53;

      if (n < -1022)

        n = -1022;

    }

  }

  u.i = (uint64_t)(0x3ff+n)<<52;

  x = y * u.f;

  return x;

}