@startuml
scale max 900*520
skinparam backgroundColor transparent
skinparam shadowing false
skinparam defaultFontName "DejaVu Sans Mono"
skinparam defaultFontSize 13
skinparam stateBorderColor #2b6f8e
skinparam stateBackgroundColor #edf6fa
skinparam ArrowColor #8295a0
top to bottom direction
title A6 STATE — binary semaphore and task readiness across ISR
state "01 EMPTY\nwaiter Blocked" as Empty
state "02 IRQ PENDING\nstimulus interrupted" as Pending
state "03 GIVEN FROM ISR\nwaiter Ready" as Given
state "04 SWITCH REQUESTED\nxHPW=true" as Switch
state "05 TAKEN\nwaiter Running" as Taken
state "06 STIMULUS RESUMED" as Resumed
[*] --> Empty
Empty --> Pending : SET_IRQ
Pending --> Given : GiveFromISR
Given --> Switch : portYIELD_FROM_ISR
Switch --> Taken : restore waiter context
Taken --> Resumed : waiter completes
Resumed --> [*]
@enduml