libpri/doc/cc_ptp_agent.fsm

/*
 * FSM pseudo code used in the design/implementation of the CC PTP agent.
 */
FSM CC_PTP_Agent
{
	State CC_STATE_IDLE {
		Init {
		}
		Prolog {
			Action Set_Selfdestruct;
		}
		Stimulus CC_EVENT_AVAILABLE {
			Next_State CC_STATE_PENDING_AVAILABLE;
		}
		Stimulus CC_EVENT_CANCEL {
			Action Set_Selfdestruct;
		}
	}
	State CC_STATE_PENDING_AVAILABLE {
		Stimulus CC_EVENT_MSG_ALERTING {
			Action Send_CC_Available(Q931_ALERTING);
			Next_State CC_STATE_AVAILABLE;
		}
		Stimulus CC_EVENT_MSG_DISCONNECT {
			Action Send_CC_Available(Q931_DISCONNECT);
			Next_State CC_STATE_AVAILABLE;
		}
		Stimulus CC_EVENT_CANCEL {
			Next_State CC_STATE_IDLE;
		}
	}
	State CC_STATE_AVAILABLE {
		/*
		 * For PTP mode the T_RETENTION timer is not defined.  However,
		 * we will use it anyway in this state to protect our resources
		 * from leaks caused by user A not requesting CC.  This timer
		 * should be set much longer than the PTMP network link to
		 * allow for variations in user A's CC offer timer.
		 */
		Epilog {
			Action Stop_T_RETENTION;
		}
		Stimulus CC_EVENT_MSG_RELEASE {
			Action Stop_T_RETENTION;
			Action Start_T_RETENTION;
		}
		Stimulus CC_EVENT_MSG_RELEASE_COMPLETE {
			Action Stop_T_RETENTION;
			Action Start_T_RETENTION;
		}
		Stimulus CC_EVENT_CC_REQUEST {
			Action Pass_Up_CC_Request;
			Action Stop_T_RETENTION;
			Next_State CC_STATE_REQUESTED;
		}
		Stimulus CC_EVENT_TIMEOUT_T_RETENTION {
			Action Pass_Up_CC_Cancel;
			Next_State CC_STATE_IDLE;
		}
		Stimulus CC_EVENT_CANCEL {
			Next_State CC_STATE_IDLE;
		}
	}
	State CC_STATE_REQUESTED {
		Stimulus CC_EVENT_CC_REQUEST_ACCEPT {
			Next_State CC_STATE_ACTIVATED;
		}
		Stimulus CC_EVENT_SIGNALING_GONE {
			/* Signaling link cleared. */
			Action Pass_Up_CC_Cancel;
			Next_State CC_STATE_IDLE;
		}
		Stimulus CC_EVENT_CANCEL {
			Action Hangup_Signaling_Link;
			Next_State CC_STATE_IDLE;
		}
	}
	State CC_STATE_ACTIVATED {
		Prolog {
			Action Reset_A_Status;
		}
		Stimulus CC_EVENT_REMOTE_USER_FREE {
			Action Pass_Up_A_Status_Indirect;
			Test = Get_A_Status;
			Test == Busy {
				Next_State CC_STATE_SUSPENDED;
			}
			Action Send_RemoteUserFree;
			Next_State CC_STATE_WAIT_CALLBACK;
		}
		Stimulus CC_EVENT_SUSPEND {
			/* Received CCBS_T_Suspend */
			Action Set_A_Status_Busy;
		}
		Stimulus CC_EVENT_RESUME {
			/* Received CCBS_T_Resume */
			Action Reset_A_Status;
		}
	}
	State CC_STATE_WAIT_CALLBACK {
		Stimulus CC_EVENT_SUSPEND {
			/* Received CCBS_T_Suspend */
			Action Set_A_Status_Busy;
			Action Pass_Up_A_Status;
			Next_State CC_STATE_SUSPENDED;
		}
	}
	State CC_STATE_SUSPENDED {
		Stimulus CC_EVENT_RESUME {
			/* Received CCBS_T_Resume */
			Action Set_A_Status_Free;
			Action Pass_Up_A_Status;
			Next_State CC_STATE_ACTIVATED;
		}
	}
	Superstate CC_ACTIVE(CC_STATE_ACTIVATED, CC_STATE_WAIT_CALLBACK, CC_STATE_SUSPENDED) {
		Prolog {
			/* Start T_CCBS5/T_CCNR5 depending upon CC mode. */
			Action Start_T_SUPERVISION;
		}
		Epilog {
			Action Stop_T_SUPERVISION;
		}
		Stimulus CC_EVENT_RECALL {
			/* Received CCBS_T_Call */
			Action Pass_Up_CC_Call;
			Action Set_Original_Call_Parameters;
		}
		Stimulus CC_EVENT_TIMEOUT_T_SUPERVISION {
			Action Pass_Up_CC_Cancel;
			Action Hangup_Signaling_Link;
			Next_State CC_STATE_IDLE;
		}
		Stimulus CC_EVENT_SIGNALING_GONE {
			/* Signaling link cleared. */
			Action Pass_Up_CC_Cancel;
			Next_State CC_STATE_IDLE;
		}
		Stimulus CC_EVENT_CANCEL {
			Action Hangup_Signaling_Link;
			Next_State CC_STATE_IDLE;
		}
	}
}