QP::QK Namespace Reference

preemptive, non-blocking kernel More...

Functions
QSchedStatus	schedLock (std::uint_fast8_t const ceiling) noexcept
void	schedUnlock (QSchedStatus const prevCeil) noexcept
void	onIdle ()

Detailed Description

preemptive, non-blocking kernel

Details

The QK namespace contains only QK facilities callable from C++. The following other QK facilities are defined in the global namespace to be callable from assembly (as extern "C"):

• QK_sched_()
• QK_activate_()
• QK_Attr

Function Documentation

schedLock()

QSchedStatus QP::QK::schedLock ( std::uint_fast8_t const ceiling )

noexcept

QK selective scheduler lock

Details

This function locks the QK scheduler to the specified ceiling.

Parameters

[in]

ceiling

preemption ceiling to which the QK scheduler needs to be locked

Returns

The previous QK Scheduler lock status, which is to be used to unlock the scheduler by restoring its previous lock status in QK::schedUnlock().

Precondition qk:100

• The QK scheduler lock cannot be called from an ISR

Note

QK::schedLock() must be always followed by the corresponding QK::schedUnlock().

See also

QK::schedUnlock()

Usage

The following example shows how to lock and unlock the QK scheduler:

std::uint32_t BSP::random() {
    QP::QSchedStatus lockStat = QP::QK::schedLock(N_PHILO); // <== lock
    std::uint32_rnd;
    . . . // access/manipulate the shared random seed resource
    QP::QK::schedUnlock(lockStat);
 
    return rnd;
}

Definition at line 67 of file qk.cpp.

schedUnlock()

void QP::QK::schedUnlock ( QSchedStatus const stat )

noexcept

QK selective scheduler unlock

Details

This function unlocks the QK scheduler to the previous status.

Parameters

[in]

stat

previous QK Scheduler lock status returned from QK::schedLock()

Precondition qk:200

• the QK scheduler cannot be unlocked: from the ISR context
• the current lock ceiling must be greater than the previous

Note

QK::schedUnlock() must always follow the corresponding QK::schedLock().

See also

QK::schedLock()

Usage

The following example shows how to lock and unlock the QK scheduler:

std::uint32_t BSP::random() {
    QP::QSchedStatus lockStat = QP::QK::schedLock(N_PHILO);
    std::uint32_rnd;
    . . . // access/manipulate the shared random seed resource
    QP::QK::schedUnlock(lockStat); // <=== unlock
 
    return rnd;
}

Definition at line 106 of file qk.cpp.

onIdle()

void QP::QK::onIdle

(

)

QK idle callback (customized in BSPs for QK)

Details

QK::onIdle() is called continuously by the QK idle loop. This callback gives the application an opportunity to enter a power-saving CPU mode, or perform some other idle processing.

Note

QK::onIdle() is invoked with interrupts enabled and must also return with interrupts enabled.