Struct agb::sync::Static

pub struct Static<T> { /* private fields */ }

A helper that implements static variables.

It ensures that even if you use the same static variable in both an IRQ and normal code, the IRQ will never observe an invalid value of the variable.

This type only works with owned values. If you need to work with borrows, consider using sync::Mutex instead.

Performance

Writing or reading from a static variable is efficient under the following conditions:

• The type is aligned to 4 bytes and can be stored in 40 bytes or less.
• The type is aligned to 2 bytes and can be stored in 2 bytes.
• The type is can be stored in a single byte.

Replacing the current value of the static variable is efficient under the following conditions:

• The type is aligned to 4 bytes and can be stored in 4 bytes or less.
• The type is can be stored in a single byte.

When these conditions are not met, static variables are handled using a fallback routine that disables IRQs and does a normal copy. This can be dangerous as disabling IRQs can cause your program to miss out on important interrupts such as V-Blank.

Consider using sync::Mutex instead if you need to use a large amount of operations that would cause IRQs to be disabled. Also consider using #[repr(align(4))] to force proper alignment for your type.

Implementations

impl<T> Static<T>

pub const fn new(val: T) -> Self

Creates a new static variable.

Examples found in repository

examples/output.rs (line 6)

static COUNT: Static<u32> = Static::new(0);

pub fn replace(&self, val: T) -> T

Replaces the current value of the static variable with another, and returns the old value.

pub fn into_inner(self) -> T

Extracts the interior value of the static variable.

impl<T: Copy> Static<T>

pub fn write(&self, val: T)

Writes a new value into this static variable.

pub fn read(&self) -> T

Reads a value from this static variable.

Trait Implementations

impl<T: Default> Default for Static<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T> Send for Static<T>

impl<T> Sync for Static<T>