Design Overview

Timer provides one-shot or periodic callbacks with millisecond resolution. Caller provides storage; framework manages state. Callbacks fired by system tick (typically 1ms from monotonic clock).

Core API

rte_timer_create(storage, config, out_handle)   // Create timer
rte_timer_start(handle)                          // Start countdown
rte_timer_stop(handle)                           // Stop countdown
rte_timer_destroy(handle)                        // Release
rte_timer_now_ms(out_now_ms)                     // Get current time

Configuration

typedef struct {
    rte_timer_mode_t mode;        // ONE_SHOT or PERIODIC
    rte_duration_ms_t period_ms;  // Period/delay in ms
    rte_timer_callback_t callback;// Called on expiry
    void *user_ctx;                // Passed to callback
} rte_timer_config_t;

Storage Model

Caller provides 64-byte storage via rte_timer_storage_t. Framework uses for internal state. Caller keeps valid for timer lifetime.

Callback Signature

typedef void (*rte_timer_callback_t)(
    rte_timer_handle_t handle,
    void *user_ctx
);

Called when timer expires. Runs in callback context (may be ISR on some OSAdapters). Keep execution time minimal.

Timer Tick System

Framework needs monotonic clock with ~1ms resolution. OSAdapter provides. Every tick, all active timers decrement countdown. On zero, callback fires.

O(1) Per Timer

Operation	Time
create()	O(1)
start()	O(1)
stop()	O(1)
destroy()	O(1)
tick()	O(n) [n = active timers]

Tick is only O(n) operation; typically called once per millisecond.

Constraints

Min period      - 1ms (timer resolution)
Max period      - 2^32 - 1 ms (~49 days)
Storage size    - 64 bytes
Callback time   - Caller's responsibility to bound