doubleToLongBits static method

int doubleToLongBits(double value)

Implementation

static int doubleToLongBits(double value) {
  const pow52 = 4503599627370496.0; // 2^52
  const pow1022 = 4.49423283715579e+307; // 2^1022
  if (value.isNaN) {
    return 0x7FF8000000000000;
  }
  int signbit = 0;
  if (value.isNegative) {
    signbit = 0x8000000000000000;
    value = -value;
  }
  if (value.isInfinite) {
    return signbit | 0x7FF0000000000000;
  } else if (value < 2.2250738585072014e-308) {
    // Denormal or zero.
    // Multiply by 2^(1022+52) to get the bits into the correct position.
    int bits = (value * pow1022 * pow52).toInt();
    return signbit | bits;
  } else {
    // Slow linear search to move bits into correct position for mantissa.
    // Use binary search or something even smarter for speed.
    int exponent = 52;
    while (value < pow52) {
      value *= 2;
      exponent -= 1;
    }
    while (value >= pow52 * 2) {
      value /= 2;
      exponent += 1;
    }
    int mantissaBits = (value - pow52).toInt();
    int exponentBits = (exponent + 1023);
    return signbit | (exponentBits << 52) | mantissaBits;
  }
}