Clock

group Clock

Functions

error_t clock_init(u64 tick_quantum)

Initialize the periodic clock subsystem.

Initialize internal state and program the first timer deadline using the provided tick quantum.

Parameters:

tick_quantum – Number of hardware timer ticks per software tick.

Returns:

error_t E_OK on success, otherwise an error code.

u64 clock_now(void)

Return the current time in hardware timer ticks.

This returns a monotonic timestamp suitable for computing deadlines.

Returns:

Current time in hardware ticks.

u64 clock_ticks_now(void)

Return the number of software ticks since boot.

Software ticks are incremented by the timer IRQ handler and advance at a rate of one per tick_quantum hardware ticks.

Returns:

Number of elapsed software ticks.

error_t clock_set_next_switch_in(u64 ticks_from_now)

Request the scheduler be woken in a number of software ticks.

Programs the next switch tick to be ticks_from_now software ticks in the future. This does not block; use clock_next_switch_tick or clock_ticks_to_next_switch to query the scheduled value.

Parameters:

ticks_from_now – Number of software ticks from now to schedule.

Returns:

error_t E_OK on success, otherwise an error code.

error_t clock_next_switch_tick(u64 *out_tick)

Obtain the currently scheduled next-switch absolute tick.

Writes the absolute software tick value at which the scheduler has requested a switch into out_tick.

Parameters:

out_tick – Pointer to u64 to receive the absolute tick value.

Returns:

error_t E_OK on success, EINVAL if out_tick is NULL, or other error codes on failure.

error_t clock_ticks_to_next_switch(u64 *out_ticks)

Obtain the number of software ticks until the next switch.

Writes into out_ticks the number of ticks remaining until the scheduled next-switch tick. If a next-switch is not scheduled, behavior is implementation-defined.

Parameters:

out_ticks – Pointer to u64 to receive remaining ticks.

Returns:

error_t E_OK on success, EINVAL if out_ticks is NULL, or other error codes on failure.