Inconsistent rounding when converting from f32

[keram88]

Hello,

I found that some f32 values are converted differently depending on whether use-intrinsics is enabled or not. I am using the 1.3.0 release version.

For example:

use half::f16;

let f = 2.9802322e-8f32;
let f2 = f16::from_f32(f);
println!("{}", f2);

prints 0 when intrinsics are enabled and 0.000000059604645 when intrinsics are not enabled.

I also found an example that is potentially a rounding direction mismatch:

use half::f16;

let f = 520.25f32;
let f2 = f16::from_f32(f);
println!("{}", f2);

prints 520 when intrinsics are enabled and 520.5 when not enabled.