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use super::{Noise, NoiseDomain, Seedable, noise::Seeded};
use num_traits::{Unsigned, PrimInt, AsPrimitive};
#[derive(Copy, Clone)]
pub struct ToFloat<Inner> {
inner: Inner,
}
impl<Inner: Noise> Noise for ToFloat<Inner> where Inner::Value: Unsigned + PrimInt + AsPrimitive<u64> {
type Value = f64;
type Unseeded = ToFloat<Inner::Unseeded>;
}
impl<Inner> ToFloat<Inner> {
pub fn new(inner: Inner) -> ToFloat<Inner> {
ToFloat { inner }
}
}
impl<Inner: Seedable> Seedable for ToFloat<Inner> {
type Seed = Inner::Seed;
type Seeded = ToFloat<Inner::Seeded>;
fn seed(self, seed: Self::Seed) -> Self::Seeded {
ToFloat { inner: self.inner.seed(seed) }
}
}
impl<Inner: Seeded> Seeded for ToFloat<Inner> {
type Config = ToFloat<Inner::Config>;
}
impl<Arg, Inner: NoiseDomain<Arg>> NoiseDomain<Arg> for ToFloat<Inner> where Inner::Value: Unsigned + PrimInt + AsPrimitive<u64> {
fn noise(&self, arg: Arg) -> Self::Value {
bits_to_f64(self.inner.noise(arg))
}
}
fn bits_to_f64<T: Unsigned + PrimInt + AsPrimitive<u64>>(value: T) -> f64 {
if value.is_zero() { 0.0 }
else {
let shift = value.leading_zeros();
let exponent = 1022 - shift;
let fraction = value.unsigned_shl(shift).unsigned_shl(1).swap_bytes().as_().swap_bytes().unsigned_shr(12);
f64::from_bits((u64::from(exponent) << 52) | fraction)
}
}