Struct PosFloat

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pub struct PosFloat(/* private fields */);

Expand description

A finite, positive f32.

This is used in many places in SMS where a negative or infinite f32 would break things: timestamps, sample rates, etc. Zero would break some of these too, but less Interestingly.

Implementations§

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pub fn new(x: f32) -> Result<PosFloat, &'static str>

Try to create a new PosFloat from an f32.

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pub const unsafe fn new_unchecked(x: f32) -> PosFloat

Create a new PosFloat from an f32, which you promise is positive and finite.

§Safety

x must be positive (sign bit of zero), and finite (exponent < max).

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pub fn new_clamped(x: f32) -> PosFloat

Create a new PosFloat from an f32. If it is non-finite or negative, return zero.

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pub fn seconds_to_frames(&self, sample_rate: PosFloat) -> u64

Interprets this PosFloat as a time in seconds, and converts it to an integer number of sample frames at the given sample rate.

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pub fn seconds_to_frac_frames(&self, sample_rate: PosFloat) -> PosFloat

Interprets this PosFloat as a time in seconds, and converts it to an potentially-non-whole-number of sample frames at the given sample rate.

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pub fn seconds_to_samples( &self, sample_rate: PosFloat, speaker_layout: SpeakerLayout, ) -> u64

Interprets this PosFloat as a time in seconds, and converts it to an integer number of samples for the given sample rate and speaker layout.

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pub fn saturating_sub(&self, differend: PosFloat) -> PosFloat

Subtract differend from ourselves and return the result. If the result would have been zero (because different is greater than self), return zero.

Methods from Deref<Target = f32>§

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pub const RADIX: u32 = 2u32

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pub const MANTISSA_DIGITS: u32 = 24u32

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pub const DIGITS: u32 = 6u32

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pub const EPSILON: f32 = 1.1920929E-7f32

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pub const MIN: f32 = -3.40282347E+38f32

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pub const MIN_POSITIVE: f32 = 1.17549435E-38f32

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pub const MAX: f32 = 3.40282347E+38f32

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pub const MIN_EXP: i32 = -125i32

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pub const MAX_EXP: i32 = 128i32

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pub const MIN_10_EXP: i32 = -37i32

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pub const MAX_10_EXP: i32 = 38i32

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pub const NAN: f32 = NaN_f32

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pub const INFINITY: f32 = +Inf_f32

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pub const NEG_INFINITY: f32 = -Inf_f32

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pub fn total_cmp(&self, other: &f32) -> Ordering

Returns the ordering between self and other.

Unlike the standard partial comparison between floating point numbers, this comparison always produces an ordering in accordance to the totalOrder predicate as defined in the IEEE 754 (2008 revision) floating point standard. The values are ordered in the following sequence:

negative quiet NaN
negative signaling NaN
negative infinity
negative numbers
negative subnormal numbers
negative zero
positive zero
positive subnormal numbers
positive numbers
positive infinity
positive signaling NaN
positive quiet NaN.

The ordering established by this function does not always agree with the PartialOrd and PartialEq implementations of f32. For example, they consider negative and positive zero equal, while total_cmp doesn’t.

The interpretation of the signaling NaN bit follows the definition in the IEEE 754 standard, which may not match the interpretation by some of the older, non-conformant (e.g. MIPS) hardware implementations.

§Example

struct GoodBoy {
    name: String,
    weight: f32,
}

let mut bois = vec![
    GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
    GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
    GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
    GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY },
    GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN },
    GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
];

bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));

// `f32::NAN` could be positive or negative, which will affect the sort order.
if f32::NAN.is_sign_negative() {
    assert!(bois.into_iter().map(|b| b.weight)
        .zip([f32::NAN, -5.0, 0.1, 10.0, 99.0, f32::INFINITY].iter())
        .all(|(a, b)| a.to_bits() == b.to_bits()))
} else {
    assert!(bois.into_iter().map(|b| b.weight)
        .zip([-5.0, 0.1, 10.0, 99.0, f32::INFINITY, f32::NAN].iter())
        .all(|(a, b)| a.to_bits() == b.to_bits()))
}