QXK Class Reference

QXK services. More...

#include <qxk.hpp>

Collaboration diagram for QXK:

Static Public Member Functions
static QSchedStatus	schedLock (std::uint_fast8_t const ceiling) noexcept
	QXK selective scheduler lock. More...
static void	schedUnlock (QSchedStatus const stat) noexcept
	QXK selective scheduler unlock. More...
static void	onIdle (void)
	QXK idle callback (customized in BSPs for QXK) More...

Detailed Description

QXK services.

Description

This class groups together QXK services. It has only static members and should not be instantiated.

Note

The QXK initialization and the QXK scheduler belong conceptually to the QXK class (as static class members). However, to avoid C++ potential name-mangling problems in assembly language, these elements are defined outside of the QXK class and outside the QP namespace with the extern "C" linkage specification.

Definition at line 144 of file qxk.hpp.

Member Function Documentation

schedLock()

QSchedStatus schedLock ( std::uint_fast8_t const  ceiling )

staticnoexcept

QXK selective scheduler lock.

Description

This function locks the QXK scheduler to the specified ceiling.

Parameters

[in]

ceiling

priority ceiling to which the QXK scheduler needs to be locked

Returns

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

Note

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

See also

QXK::schedUnlock()

Usage

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

std::uint32_t BSP::random(void) {
 
    // lock the scheduler around l_rnd up to the (N_PHILO + 1U) ceiling
    QP::QSchedStatus lockStat = QP::QXK::schedLock(N_PHILO + 1U);
 
    // "Super-Duper" Linear Congruential Generator (LCG)
    // LCG(2^32, 3*7*11*13*23, 0, seed)
    //
    uint32_t rnd = l_rnd * (3U*7U*11U*13U*23U);
    l_rnd = rnd; // set for the next time
 
    QP::QXK::schedUnlock(lockStat); // unlock sched after accessing l_rnd
 
    return (rnd >> 8);
}
 

Precondition

The QXK scheduler lock:

• cannot be called from an ISR;

Definition at line 238 of file qxk.cpp.

schedUnlock()

void schedUnlock ( QSchedStatus const  stat )

staticnoexcept

QXK selective scheduler unlock.

Description

This function unlocks the QXK scheduler to the previous status.

Parameters

[in]

stat

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

Note

A QXK scheduler can be locked from both basic threads (AOs) and extended threads and the scheduler locks can nest.

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

See also

QXK::schedLock()

Usage

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

std::uint32_t BSP::random(void) {
 
    // lock the scheduler around l_rnd up to the (N_PHILO + 1U) ceiling
    QP::QSchedStatus lockStat = QP::QXK::schedLock(N_PHILO + 1U);
 
    // "Super-Duper" Linear Congruential Generator (LCG)
    // LCG(2^32, 3*7*11*13*23, 0, seed)
    //
    uint32_t rnd = l_rnd * (3U*7U*11U*13U*23U);
    l_rnd = rnd; // set for the next time
 
    QP::QXK::schedUnlock(lockStat); // unlock sched after accessing l_rnd
 
    return (rnd >> 8);
}
 

Precondition

The scheduler cannot be unlocked:

• from the ISR context; and
• the current lock priority must be greater than the previous

Definition at line 293 of file qxk.cpp.

onIdle()

static void onIdle ( void  )

static

QXK idle callback (customized in BSPs for QXK)

Description

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

Note

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

See also

QP::QF::onIdle()

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

• qxk.hpp
• qxk.cpp