user
49 lines
1.8 KiB
Markdown
49 lines
1.8 KiB
Markdown
# K14 — Software timer and the timer daemon task
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K14 implements a freestanding, non-copyable C++ SoftwareTimer wrapper over
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statically allocated FreeRTOS timers. OneShotTimer and PeriodicTimer encode the
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reload policy in the type. The constructor creates the timer, while start,
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reset, change_period and stop remain explicit commands sent to the timer daemon.
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The target experiment starts both timers before the scheduler:
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command acceptance snapshot: callbacks = 0
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periodic initial period 2: ticks 2, 4
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one-shot reset at tick 1: callback at tick 6, then inactive
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periodic change at tick 4: next callback at tick 7
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periodic stop: inactive, no fourth callback
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The callback checks that its current task is xTimerGetTimerDaemonTaskHandle()
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and that the task name begins with Tmr S. It also records a stack pointer
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different from the verifier task. Timer control blocks, verifier TCB and stacks
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live in .bss; creating both timers leaves the heap unchanged.
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## Build
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make check
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This runs a host policy test, ABI/storage checks and the deterministic Hazard3
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simulation.
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## Debug
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riscv64-unknown-elf-gdb build/task01_sw_timer/prog.elf
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b software_timer_debug_checkpoint
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p g_start_commands_accepted
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p g_callbacks_when_start_returned
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p g_reset_tick
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p g_change_tick
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p g_one_shot_tick
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p g_periodic_ticks
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p g_daemon_handle_match
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p g_daemon_name_match
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p g_timer_pass
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## Lifetime boundary
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The timer ID stores a pointer to the typed callback context. Therefore the
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StaticTimer_t storage, wrapper and context must remain alive while a command or
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callback can still be pending. A successful API return proves queue acceptance,
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not callback completion. Timer callbacks execute in the shared daemon task and
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must not block.
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