Trait gstreamer::prelude::MulDiv[−]

pub trait MulDiv<RHS = Self> {
    type Output;
    fn mul_div_floor(self, num: RHS, denom: RHS) -> Option<Self::Output>;

    fn mul_div_round(self, num: RHS, denom: RHS) -> Option<Self::Output>;

    fn mul_div_ceil(self, num: RHS, denom: RHS) -> Option<Self::Output>;
}
Expand description

Trait for calculating val * num / denom with different rounding modes and overflow protection.

Implementations of this trait have to ensure that even if the result of the multiplication does not fit into the type, as long as it would fit after the division the correct result has to be returned instead of None. None only should be returned if the overall result does not fit into the type.

This specifically means that e.g. the u64 implementation must, depending on the arguments, be able to do 128 bit integer multiplication.

Associated Types

Output type for the methods of this trait.

Required methods

Calculates floor(val * num / denom), i.e. the largest integer less than or equal to the result of the division.

Example

extern crate muldiv;
use muldiv::MulDiv;

let x = 3i8.mul_div_floor(4, 2);
assert_eq!(x, Some(6));

let x = 5i8.mul_div_floor(2, 3);
assert_eq!(x, Some(3));

let x = (-5i8).mul_div_floor(2, 3);
assert_eq!(x, Some(-4));

let x = 3i8.mul_div_floor(3, 2);
assert_eq!(x, Some(4));

let x = (-3i8).mul_div_floor(3, 2);
assert_eq!(x, Some(-5));

let x = 127i8.mul_div_floor(4, 3);
assert_eq!(x, None);

Calculates round(val * num / denom), i.e. the closest integer to the result of the division. If both surrounding integers are the same distance (x.5), the one with the bigger absolute value is returned (round away from 0.0).

Example

extern crate muldiv;
use muldiv::MulDiv;

let x = 3i8.mul_div_round(4, 2);
assert_eq!(x, Some(6));

let x = 5i8.mul_div_round(2, 3);
assert_eq!(x, Some(3));

let x = (-5i8).mul_div_round(2, 3);
assert_eq!(x, Some(-3));

let x = 3i8.mul_div_round(3, 2);
assert_eq!(x, Some(5));

let x = (-3i8).mul_div_round(3, 2);
assert_eq!(x, Some(-5));

let x = 127i8.mul_div_round(4, 3);
assert_eq!(x, None);

Calculates ceil(val * num / denom), i.e. the the smallest integer greater than or equal to the result of the division.

Example

extern crate muldiv;
use muldiv::MulDiv;

let x = 3i8.mul_div_ceil(4, 2);
assert_eq!(x, Some(6));

let x = 5i8.mul_div_ceil(2, 3);
assert_eq!(x, Some(4));

let x = (-5i8).mul_div_ceil(2, 3);
assert_eq!(x, Some(-3));

let x = 3i8.mul_div_ceil(3, 2);
assert_eq!(x, Some(5));

let x = (-3i8).mul_div_ceil(3, 2);
assert_eq!(x, Some(-4));

let x = (127i8).mul_div_ceil(4, 3);
assert_eq!(x, None);

Implementations on Foreign Types

Implementors