Scheduler

Fixed-priority cooperative task scheduler with WCET tracking.

Header: core/ecu_scheduler.h

enum sched_priority_t

Task priority levels (lower value = higher priority).

Values:

enumerator SCHED_PRIO_CRITICAL: Safety-critical (e.g. control loop).

enumerator SCHED_PRIO_HIGH: High priority (e.g. watchdog).

enumerator SCHED_PRIO_MEDIUM: Medium priority (e.g. telemetry).

enumerator SCHED_PRIO_LOW: Low priority (e.g. housekeeping).

typedef void (*sched_task_fn)(void *ctx): Task function signature.

void ecu_sched_init(ecu_scheduler_t *sched)

Initialise the scheduler.

Parameters:

sched – [out] Scheduler context.

int ecu_sched_add(ecu_scheduler_t *sched, const char *name, sched_task_fn fn, void *ctx, sched_priority_t prio, uint32_t interval_ms)

Register a periodic task.

Parameters:

sched – [inout] Scheduler context.
name – [in] Task name (pointer must remain valid).
fn – [in] Task function.
ctx – [in] User context passed to fn.
prio – [in] Task priority.
interval_ms – [in] Execution interval in milliseconds.

Returns:

Task index on success, or -1 if the table is full.

void ecu_sched_tick(ecu_scheduler_t *sched, uint32_t now_ms)

Execute one scheduler tick.

Runs all tasks whose interval has elapsed, in priority order.

Parameters:

sched – [inout] Scheduler context.
now_ms – [in] Current time in milliseconds.

uint32_t ecu_sched_get_wcet(const ecu_scheduler_t *sched, int task_idx)

Get worst-case execution time for a task.

Parameters:

sched – [in] Scheduler context.
task_idx – [in] Task index (from ecu_sched_add()).

Returns:

WCET in microseconds.

bool ecu_sched_any_overrun(const ecu_scheduler_t *sched)

Check if any task has experienced an overrun.

Parameters:

sched – [in] Scheduler context.

Returns:

true if any task has overrun its interval.

SCHED_MAX_TASKS: Maximum registered tasks.

struct sched_task_t

#include <ecu_scheduler.h>

Registered task descriptor.

Public Members

const char *name: Human-readable task name.

sched_task_fn fn: Task function pointer.

void *ctx: User context for fn.

sched_priority_t priority: Execution priority.

uint32_t interval_ms: Execution interval (ms).

uint32_t last_run_ms: Timestamp of last execution.

uint32_t worst_case_us: Worst-case execution time (us).

uint32_t run_count: Total executions.

bool overrun: Set if interval was exceeded.

struct ecu_scheduler_t

#include <ecu_scheduler.h>

Scheduler context.

Public Members

sched_task_t tasks[8]: Registered tasks.

int task_count: Number of registered tasks.

uint32_t tick_ms: Current tick time.