///
/// Note that this function is distinct from casting.
///
+ /// Returns `Err(())` if the representation of a signaling NaN "sNaN"
+ /// float, is passed to the function.
+ ///
/// ```
/// #![feature(float_bits_conv)]
/// use std::f64;
- /// let difference = (f64::from_bits(0x4029000000000000) - 12.5).abs();
+ /// let v = f64::from_bits(0x4029000000000000).unwrap();
+ /// let difference = (v - 12.5).abs();
/// assert!(difference <= 1e-5);
+ /// // Example for a signaling NaN value:
+ /// assert_eq!(f64::from_bits(0x7FF0000000000001), Err(()));
/// ```
#[unstable(feature = "float_bits_conv", reason = "recently added", issue = "0")]
#[inline]
- pub fn from_bits(v: u64) -> Self {
- unsafe { ::mem::transmute(v) }
+ pub fn from_bits(v: u64) -> Result<Self, ()> {
+ match v {
+ 0x7FF0000000000001 ... 0x7FF7FFFFFFFFFFFF |
+ 0xFFF0000000000001 ... 0xFFF7FFFFFFFFFFFF => Err(()),
+ _ => Ok(unsafe { ::mem::transmute(v) }),
+ }
}
}
assert_eq!((12.5f64).to_bits(), 0x4029000000000000);
assert_eq!((1337f64).to_bits(), 0x4094e40000000000);
assert_eq!((-14.25f64).to_bits(), 0xc02c800000000000);
- assert_approx_eq!(f64::from_bits(0x3ff0000000000000), 1.0);
- assert_approx_eq!(f64::from_bits(0x4029000000000000), 12.5);
- assert_approx_eq!(f64::from_bits(0x4094e40000000000), 1337.0);
- assert_approx_eq!(f64::from_bits(0xc02c800000000000), -14.25);
+ assert_approx_eq!(f64::from_bits(0x3ff0000000000000).unwrap(), 1.0);
+ assert_approx_eq!(f64::from_bits(0x4029000000000000).unwrap(), 12.5);
+ assert_approx_eq!(f64::from_bits(0x4094e40000000000).unwrap(), 1337.0);
+ assert_approx_eq!(f64::from_bits(0xc02c800000000000).unwrap(), -14.25);
}
}