QTimeEvt Class Reference

Time Event class. More...

#include "qp.h"

Inheritance diagram for QTimeEvt:

Public Member Functions
void	QTimeEvt_ctorX (QTimeEvt *const me, QActive *const act, enum_t const sig, uint_fast8_t const tickRate)
void	QTimeEvt_armX (QTimeEvt *const me, QTimeEvtCtr const nTicks, QTimeEvtCtr const interval)
bool	QTimeEvt_disarm (QTimeEvt *const me)
bool	QTimeEvt_rearm (QTimeEvt *const me, QTimeEvtCtr const nTicks)
bool	QTimeEvt_wasDisarmed (QTimeEvt *const me)
QTimeEvtCtr	QTimeEvt_currCtr (QTimeEvt const *const me)

Static Public Member Functions
bool	QTimeEvt_noActive (uint_fast8_t const tickRate)
Static Public Member Functions inherited from QEvt
static QEvt *	QEvt_ctor (QEvt *const me, enum_t const sig)

Public Attributes
QEvt	super
Public Attributes inherited from QEvt
QSignal	sig

Static Private Member Functions
void	QTimeEvt_tick_ (uint_fast8_t const tickRate, void const *const sender)
void	QTimeEvt_tick1_ (uint_fast8_t const tickRate, void const *const sender)

Private Attributes
struct QTimeEvt *volatile	next
void *volatile	act
QTimeEvtCtr volatile	ctr
QTimeEvtCtr	interval
QTimeEvt	QTimeEvt_timeEvtHead_ [QF_MAX_TICK_RATE]

Detailed Description

Time Event class.

Description

Time events are special QF events equipped with the notion of time passage. The basic usage model of the time events is as follows. An active object allocates one or more QTimeEvt objects (provides the storage for them). When the active object needs to arrange for a timeout, it arms one of its time events to fire either just once (one-shot) or periodically. Each time event times out independently from the others, so a QF application can make multiple parallel timeout requests (from the same or different active objects). When QF detects that the appropriate moment has arrived, it inserts the time event directly into the recipient's event queue. The recipient then processes the time event just like any other event.

Time events, as any other QF events derive from the QEvt base class. Typically, you will use a time event as-is, but you can also further derive more specialized time events from it by adding some more data members and/or specialized functions that operate on the specialized time events.

Internally, the armed time events are organized into linked lists–one list for every supported ticking rate. These linked lists are scanned in every invocation of the QTIMEEVT_TICK_X() macro. Only armed (timing out) time events are in the list, so only armed time events consume CPU cycles.

Traceability

• ARC-QP-02_60

Note

QF manages the time events in the QTIMEEVT_TICK_X() macro, which must be called periodically, from the clock tick ISR or from other periodic source. QTIMEEVT_TICK_X() caYou might also use the special QTicker active object.

Even though QTimeEvt is a subclass of QEvt, QTimeEvt instances can NOT be allocated dynamically from event pools. In other words, it is illegal to allocate QTimeEvt instances with the Q_NEW() or Q_NEW_X() macros.

Definition at line 957 of file qp.h.

Member Function Documentation

QTimeEvt_ctorX()

QTimeEvt::QTimeEvt_ctorX	(	QTimeEvt *const	me,
		QActive *const	act,
		enum_t const	sig,
		uint_fast8_t const	tickRate
	)

The "extended" constructor to initialize a Time Event.

Description

When creating a time event, you must commit it to a specific active object act, tick rate tickRate and event signal sig. You cannot change these attributes later.

Parameters

[in,out]	me	current instance pointer (see Object Orientation)
[in]	act	pointer to the active object associated with this time event. The time event will post itself to this AO.
[in]	sig	signal to associate with this time event.
[in]	tickRate	system clock tick rate to associate with this time event in the range [0..15].

Precondition qf_time:300

• the signal sig must be valid
• the tick rate tickRate must be in range

Note

You should call QTimeEvt_ctorX() exactly once for every Time Event object before arming the Time Event. The ideal place for calling QTimeEvt_ctorX() is the constructor of the associated AO.

QTimeEvt_armX()

QTimeEvt::QTimeEvt_armX	(	QTimeEvt *const	me,
		QTimeEvtCtr const	nTicks,
		QTimeEvtCtr const	interval
	)

Arm a time event (extended version for one shot or periodic time event)

Description

Arms a time event to fire in a specified number of clock ticks and with a specified interval. If the interval is zero, the time event is armed for one shot ('one-shot' time event). When the timeout expires, the time event gets directly posted (using the FIFO policy) into the event queue of the host active object. After posting, a one-shot time event gets automatically disarmed while a periodic time event (interval != 0) is automatically re-armed.

A time event can be disarmed at any time by calling QTimeEvt_disarm(). Also, a time event can be re-armed to fire in a different number of clock ticks by calling the QTimeEvt_rearm().

Parameters

[in,out]	me	current instance pointer (see Object Orientation)
[in]	nTicks	number of clock ticks (at the associated rate) to rearm the time event with.
[in]	interval	interval (in clock ticks) for periodic time event.

Precondition qf_time:400

• the host AO must be valid,
• the time eveht must be disarmed,
• the number of clock ticks cannot be zero,
• the signal must be valid.

Attention

Arming an already armed time event is not allowed and is considered a programming error. The QP/C framework will assert if it detects an attempt to arm an already armed time event.

Traceability

• DVR-QP-MC4-R11_05

Usage

The following example shows how to arm a periodic time event as well as one-shot time event from a state machine of an active object:

QState Game_show_logo(Tunnel * const me, QEvt const * const e) {
    QState status_;
    switch (e->sig) {
        case Q_ENTRY_SIG: {
            // arm periodic time event
            QTimeEvt_armX(&me->blinkTimeEvt,     // <===
                          BSP_TICKS_PER_SEC/2U,  // one-time delay
                          BSP_TICKS_PER_SEC/2U); // interva
            // arm a one-shot time event
            QTimeEvt_armX(&me->screenTimeEvt,
                          BSP_TICKS_PER_SEC*5U,  // one-time delay
                          0U);      // interval (0 == no interval)
            . . .
            status_ = Q_HANDLED();
            break;
        }
        . . .

Definition at line 97 of file qf_time.c.

QTimeEvt_disarm()

QTimeEvt::QTimeEvt_disarm

(

QTimeEvt *const

me

)

Disarm a time event.

Description

Disarm the time event so it can be safely reused.

Remarks

Disarming an already disarmed time event is fine.

Parameters

[in,out]

me

current instance pointer (see Object Orientation)

Returns

'true' if the time event was truly disarmed, that is, it was running. The return of 'false' means that the time event was not truly disarmed, because it was not running. The 'false' return is only possible for one-shot time events that have been automatically disarmed upon expiration. In this case the 'false' return means that the time event has already been posted or published and should be expected in the active object's state machine.

Definition at line 157 of file qf_time.c.

QTimeEvt_rearm()

QTimeEvt::QTimeEvt_rearm	(	QTimeEvt *const	me,
		QTimeEvtCtr const	nTicks
	)

Rearm a time event.

Description

Rearms a time event with a new number of clock ticks. This function can be used to adjust the current period of a periodic time event or to prevent a one-shot time event from expiring (e.g., a watchdog time event). Rearming a periodic timer leaves the interval unchanged and is a convenient method to adjust the phasing of a periodic time event.

Parameters

[in,out]	me	current instance pointer (see Object Orientation)
[in]	nTicks	number of clock ticks (at the associated rate) to rearm the time event with.

Returns

'true' if the time event was running as it was re-armed. The 'false' return means that the time event was not truly rearmed because it was not running. The 'false' return is only possible for one-shot time events that have been automatically disarmed upon expiration. In this case the 'false' return means that the time event has already been posted or published and should be expected in the active object's state machine.

Precondition qf_time:600

• AO must be valid
• tick rate must be in range
• nTicks must not be zero,
• the signal of this time event must be valid

Traceability

• DVR-QP-MC4-R11_05

Definition at line 203 of file qf_time.c.

QTimeEvt_wasDisarmed()

QTimeEvt::QTimeEvt_wasDisarmed

(

QTimeEvt *const

me

)

Check the "was disarmed" status of a time event.

Description

Useful for checking whether a one-shot time event was disarmed in the QTimeEvt_disarm() operation.

Parameters

[in,out]

me

current instance pointer (see Object Orientation)

Returns

'true' if the time event was truly disarmed in the last QTimeEvt_disarm() operation. The 'false' return means that the time event was not truly disarmed, because it was not running at that time. The 'false' return is only possible for one-shot time events that have been automatically disarmed upon expiration. In this case the 'false' return means that the time event has already been posted or published and should be expected in the active object's event queue.

Note

This function has a side effect of setting the "was disarmed" status, which means that the second and subsequent times this function is called the function will return 'true'.

Definition at line 269 of file qf_time.c.

QTimeEvt_currCtr()

QTimeEvt::QTimeEvt_currCtr

(

QTimeEvt const *const

me

)

Get the current value of the down-counter of a time event.

Description

Useful for checking how many clock ticks (at the tick rate associated with the time event) remain until the time event expires.

Parameters

[in,out]

me

current instance pointer (see Object Orientation)

Returns

For an armed time event, the function returns the current value of the down-counter of the given time event. If the time event is not armed, the function returns 0.

Definition at line 285 of file qf_time.c.

QTimeEvt_tick_()

QTimeEvt::QTimeEvt_tick_ ( uint_fast8_t const  tickRate, void const *const  sender  )

staticprivate

Processes all armed time events at every clock tick.

Description

This internal helper function processes all armed QTimeEvt objects associated wit the tick rate tickRate.

This function must be called periodically from a time-tick ISR or from a task so that QF can manage the timeout events assigned to the given system clock tick rate.

Parameters

[in]	tickRate	clock tick rate serviced in this call [1..15].
[in]	sender	pointer to a sender object (only for QS tracing)

Note

this function should be called only via the macro QTIMEEVT_TICK_X().

The calls to QTimeEvt_tick_() with different tickRate parameter can preempt each other. For example, higher clock tick rates might be serviced from interrupts while others from tasks (active objects).

Traceability

• DVR-QP-MC4-R11_05

Definition at line 296 of file qf_time.c.

QTimeEvt_tick1_()

QTimeEvt::QTimeEvt_tick1_ ( uint_fast8_t const  tickRate, void const *const  sender  )

staticprivate

Processes one clock tick for QUTest

Definition at line 250 of file qutest.c.

QTimeEvt_noActive()

QTimeEvt::QTimeEvt_noActive ( uint_fast8_t const  tickRate )

static

Check if any time events are active at a given clock tick rate.

Parameters

[in]

tickRate

system clock tick rate to find out about.

Returns

'true' if no time events are armed at the given tick rate and 'false' otherwise.

Precondition qf_time:800

• the tick rate must be in range

Note

This function should be called in critical section.

Definition at line 434 of file qf_time.c.

Member Data Documentation

super

QEvt QTimeEvt::super

Definition at line 959 of file qp.h.

next

QTimeEvt::next

private

Link to the next time event in the list

Definition at line 964 of file qp.h.

act

QTimeEvt::act

private

Active object that receives the time events

Definition at line 967 of file qp.h.

ctr

QTimeEvt::ctr

private

Down-counter of the time event.

Description

The down-counter is decremented by 1 in every QTimeEvt_tick_() call. The time event fires (gets posted or published) when the down-counter reaches zero.

Definition at line 970 of file qp.h.

interval

QTimeEvt::interval

private

Interval for periodic time event (zero for one-shot time event)

Description

The value of the interval is re-loaded to the internal down-counter when the time event expires, so that the time event keeps timing out periodically.

Definition at line 973 of file qp.h.

QTimeEvt_timeEvtHead_

QTimeEvt::QTimeEvt_timeEvtHead_

private

Array of heads of linked lists of time events, one for every clock tick rate

Definition at line 977 of file qp.h.

---

The documentation for this class was generated from the following files:

• qp.h
• qf_time.c
• qutest.c
• qp.dox