Struct Speed 

pub struct Speed(pub u16);

A traction speed: IEEE half-float in scale m/s, sign bit = reverse.

The inner u16 is the raw half-float as sent on the wire (see crate::float16). The Traction Control Standard expresses speed in scale meters per second, with the sign bit as the direction: set means reverse. Direction is therefore kept even at zero speed, which is why there are two stop values. The magnitude accessors (Speed::mps, Speed::mph) always return a non-negative number; use Speed::is_reverse for the direction.

use rolcb::traction::Speed;

let s = Speed::from_mph(30.0, true);
assert!(s.is_reverse());
assert!((s.mph() - 30.0).abs() < 0.05);
assert!(s.mps() > 0.0);

assert_eq!(Speed::from_mps(0.0, true), Speed::STOP_REVERSE);
assert_eq!(Speed::default(), Speed::STOP_FORWARD);
assert!(Speed::NAN.is_nan());

Tuple Fields

0: u16

Implementations

impl Speed

pub const NAN: Speed

“Not available”, used in Query Speed replies.

pub const STOP_FORWARD: Speed

Zero speed, facing forward (+0.0, 0x0000).

pub const STOP_REVERSE: Speed

Zero speed, facing reverse (-0.0, 0x8000).

pub fn from_mps(mps: f32, reverse: bool) -> Speed

Build from a magnitude in scale m/s and a direction. The sign of mps is ignored; only reverse sets the direction.

pub fn from_mph(mph: f32, reverse: bool) -> Speed

Build from a magnitude in scale miles per hour (1 mph = 0.44704 m/s) and a direction.

pub fn is_reverse(self) -> bool

True if the direction (sign) bit is set.

pub fn is_nan(self) -> bool

True for any half-float NaN, such as Speed::NAN.

pub fn mps(self) -> f32

Magnitude in m/s (never negative; see Speed::is_reverse).

For a NaN speed such as Speed::NAN (“not available”) this returns f32::NAN, so check Speed::is_nan before doing arithmetic or comparisons with the result.

use rolcb::traction::Speed;
assert!(Speed::NAN.mps().is_nan());
assert_eq!(Speed::from_mps(2.0, true).mps(), 2.0);

pub fn mph(self) -> f32

Magnitude in mph. DCC command stations conventionally map mph 1:1 onto 128-step speed steps (126 = full). NaN for a NaN speed, like Speed::mps.

Trait Implementations

impl Clone for Speed

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Speed

impl Debug for Speed

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Speed

fn default() -> Self

Returns the “default value” for a type.

impl Eq for Speed

impl Hash for Speed

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Speed

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Speed