Struct TimerDevice

pub struct TimerDevice {
    pub vect: u8,
    pub priority: u8,
    pub enabled: bool,
    /* private fields */
}

A timer device that triggers an interrupt after a configured number (or range) of instructions.

This is not part of LC-3 specification, so the design decision made (such as default interrupt vector, priority level) are not reflective of LC-3’s choices.

Fields

vect: u8

The interrupt vector.

priority: u8

The priority.

Note that if this exceeds 7, it will be treated as though it is 7.

enabled: bool

Whether this timer can trigger an interrupt.

Implementations

impl TimerDevice

pub fn new( seed: Option<u64>, range: impl RangeBounds<u32>, vect: u8, priority: u8, ) -> Self

Creates a new timer device.

• seed: Sets the seed for the timer’s RNG. This can be None if RNG does not need to be deterministic or if range can only be exactly one value.
• range: Sets the range of possible number of instructions before interrupt trigger.
• vect and priority: Initializes the interrupt vector and priority values.

pub fn get_range(&self) -> impl RangeBounds<u32>

Gets the range of possible number of instructions before the interrupt is triggered.

pub fn set_range(&mut self, r: impl RangeBounds<u32>) -> &mut Self

Sets the number of instructions before the interrupt is triggered to a range of values.

pub fn set_exact(&mut self, n: u32) -> &mut Self

Sets the number of instructions before the interrupt is triggered to an exact number.

pub fn get_remaining(&self) -> u32

Gets the number of instructions remaining until the interrupt triggers.

pub fn reset_remaining(&mut self)

Resets the remaining time.

Trait Implementations

impl Debug for TimerDevice

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

Formats the value using the given formatter.

impl Default for TimerDevice

fn default() -> Self

Creates a timer with default parameters.

The default parameters here are:

• non-deterministic RNG
• Triggers a timer interrupt every 50 instructions
• Binds to interrupt vector 0x81
• Interrupt priority 4
• Disabled

(These are arbitrary.)

impl ExternalDevice for TimerDevice

fn io_read(&mut self, _addr: u16, _effectful: bool) -> Option<u16>

Reads the data at the given memory-mapped address.

fn io_write(&mut self, _addr: u16, _data: u16) -> bool

Writes the data to the given memory-mapped address.

fn io_reset(&mut self)

Resets device.

fn poll_interrupt(&mut self) -> Option<Interrupt>

During each instruction cycle, this function is called once to see whether to trigger an interrupt.