Local Timer (for each LAPIC / CPU) More...

Classes
struct	ControlRegister.__unnamed56__

Enumerations
enum	DeliveryStatus { IDLE = 0 , SEND_PENDING = 1 }
	Timer Delivery Status.

enum	TimerMode { ONE_SHOT = 0 , PERIODIC = 1 , DEADLINE = 2 }
	Timer Mode.

enum	Mask { NOT_MASKED = 0 , MASKED = 1 }
	Timer Mask.

Functions
uint32_t	ticks (void)
	Determines the LAPIC timer frequency. More...

void	set (uint32_t counter, uint8_t divide, uint8_t vector, bool periodic, bool masked=false)
	Set the LAPIC timer. More...

Register	getClockDiv (uint8_t div)
	Calculate the bit mask for the LAPIC-timer divider. More...

Detailed Description

Local Timer (for each LAPIC / CPU)

See also: ISDMv3 10.5.4 APIC Timer

Class Documentation

◆ LAPIC::Timer::ControlRegister.unnamed56

struct LAPIC::Timer::ControlRegister.__unnamed56__

Class Members
uint32_t	vector: 8	Vector.
uint32_t	__pad0__: 4
DeliveryStatus	delivery_status: 1	Delivery Status.
uint32_t	__pad1__: 3
Mask	masked: 1	Interrupt Mask (if set, interrupt will not trigger)
TimerMode	timer_mode: 2	Timer Mode.
uint32_t	__pad2__: 13

Function Documentation

◆ ticks()

uint32_t LAPIC::Timer::ticks ( void )

Determines the LAPIC timer frequency.

This function will calculate the number of LAPIC-timer ticks passing in the course of one millisecond. To do so, this function will rely on PIT timer functionality and measure the tick delta between start and end of waiting for a predefined period.

For measurement, the LAPIC-timer single-shot mode (without interrupts) is used; after measurement, the timer is disabled again.

Note: The timer is counting towards zero.

Returns: Number of LAPIC-timer ticks per millisecond

◆ set()

void LAPIC::Timer::set	(	uint32_t	counter,
		uint8_t	divide,
		uint8_t	vector,
		bool	periodic,
		bool	masked = `false`
	)

Set the LAPIC timer.

Parameters

counter	Initial counter value; decremented on every LAPIC timer tick
divide	Divider (power of 2, i.e., 1 2 4 8 16 32...) used as prescaler between bus frequency and LAPIC timer frequency: `LAPIC timer frequency = divide * bus frequency`. `divide` is a numerical parameter, the conversion to the corresponding bit mask is done internally by calling getClockDiv().
vector	Interrupt vector number to be triggered on counter expiry
periodic	If set, the interrupt will be issued periodically
masked	If set, interrupts on counter expiry are suppressed

◆ getClockDiv()

Register LAPIC::Timer::getClockDiv ( uint8_t div )

Calculate the bit mask for the LAPIC-timer divider.

Parameters

div	Divider, must be power of two: 1, 2, 4, 8, 16, 32, 64, 128

Returns: Bit mask for LAPIC::setTimer() or 0xff if div is invalid.

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