File syn_timer.c¶

FileList > sched > syn_timer.c

Software timer implementation.

#include "../port/syn_port_system.h"
#include "../util/syn_assert.h"
#include "syn_timer.h"

Public Functions¶

Type	Name
bool	syn_timer_expired (SYN_Timer * timer) Poll whether the timer has expired.
void	syn_timer_init (SYN_Timer * timer, uint32_t period_ms, bool periodic, SYN_TimerCallback callback, void * user_data) Initialize a software timer.
uint32_t	syn_timer_next_expiry (const SYN_Timer * timers, size_t count) Get the earliest expiry tick among a set of active timers.
uint32_t	syn_timer_remaining (const SYN_Timer * timer) Get the remaining time until the next expiry.
void	syn_timer_service (SYN_Timer * timers, size_t count) Service an array of timers.
void	syn_timer_set_period (SYN_Timer * timer, uint32_t period_ms) Change the timer's period. Takes effect on next start or next periodic reload.
void	syn_timer_start (SYN_Timer * timer) Start (or restart) the timer.
void	syn_timer_stop (SYN_Timer * timer) Stop the timer. It will not fire until started again.

Public Functions Documentation¶

function syn_timer_expired¶

Poll whether the timer has expired.

bool syn_timer_expired (
    SYN_Timer * timer
)

If expired and periodic, the timer is automatically re-armed. If expired and one-shot, the timer is stopped.

This can be used instead of (or in addition to) the callback.

Parameters:

timer Timer to check.

Returns:

true if the timer has expired since the last check.

function syn_timer_init¶

Initialize a software timer.

void syn_timer_init (
    SYN_Timer * timer,
    uint32_t period_ms,
    bool periodic,
    SYN_TimerCallback callback,
    void * user_data
)

The timer is created in the stopped state. Call syn_timer_start() to begin counting.

Parameters:

timer Timer to initialize.
period_ms Period in milliseconds.
periodic true for repeating timer, false for one-shot.
callback Function called on expiry (may be NULL if using polling).
user_data User context pointer passed to callback.

function syn_timer_next_expiry¶

Get the earliest expiry tick among a set of active timers.

uint32_t syn_timer_next_expiry (
    const SYN_Timer * timers,
    size_t count
)

Scans the timer array and returns the minimum target_tick of any active timer whose deadline is in the future. Used by the tickless scheduler to account for software timer wakeups.

Parameters:

timers Array of timers to scan.
count Number of timers in the array.

Returns:

Earliest expiry tick, or UINT32_MAX if no timers are active or all have already expired.

function syn_timer_remaining¶

Get the remaining time until the next expiry.

uint32_t syn_timer_remaining (
    const SYN_Timer * timer
)

Parameters:

timer Timer to query.

Returns:

Remaining milliseconds, or 0 if expired/stopped.

function syn_timer_service¶

Service an array of timers.

void syn_timer_service (
    SYN_Timer * timers,
    size_t count
)

Checks each timer for expiry and calls its callback if set. Call this from your main loop, a scheduler task, or a periodic ISR.

Parameters:

timers Array of timers.
count Number of timers in the array.

function syn_timer_set_period¶

Change the timer's period. Takes effect on next start or next periodic reload.

void syn_timer_set_period (
    SYN_Timer * timer,
    uint32_t period_ms
)

Parameters:

timer Timer.
period_ms New period in milliseconds.

function syn_timer_start¶

Start (or restart) the timer.

void syn_timer_start (
    SYN_Timer * timer
)

Sets the target tick to now + period_ms and marks the timer active.

Parameters:

timer Timer to start.

function syn_timer_stop¶

Stop the timer. It will not fire until started again.

void syn_timer_stop (
    SYN_Timer * timer
)

Parameters:

timer Timer to stop.

The documentation for this class was generated from the following file src/syntropic/sched/syn_timer.c