QP/C  8.0.0
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QV Class Reference

QV non-preemptive kernel (QV namespace emulated as a "class" in C) More...

#include "qv.h"

Static Public Member Functions

void QV_schedDisable (uint_fast8_t const ceiling)
 
void QV_schedEnable (void)
 
void QV_onIdle (void)
 

Private Attributes

QV_Attr QV_priv_
 

Detailed Description

QV non-preemptive kernel (QV namespace emulated as a "class" in C)

Definition at line 42 of file qv.h.

Member Function Documentation

◆ QV_schedDisable()

void QV_schedDisable ( uint_fast8_t const ceiling)
static

QV selective scheduler disable

Details
This function disables the QV scheduler from scheduling threads below the specified ceiling. The main purpose of disabling the QV scheduler is to avoid scheduling threads that might take too long and overruon the next clock tick, for example.
Parameters
[in]ceilingpreemption ceiling upto which the QV scheduler needs to be disabled
Note
QV_schedDisable() must be unlocked with QV_schedEnable() at some point, but this is typically done in the system clock tick ISR.
See also
QV_schedEnable()
Usage
The following example shows how to disable the QV scheduler:
static QState Sporadic3_busy(Sporadic3 * const me, QEvt const * const e) {
QState status_;
switch (e->sig) {
//${AOs::Sporadic3::SM::active::busy::REMINDER}
case REMINDER_SIG: {
uint16_t toggles = me->total - me->done;
if (toggles > me->per_rtc) {
toggles = me->per_rtc;
}
me->done += toggles;
for (; toggles > 0U; --toggles) {
BSP_d4on();
BSP_d4off();
}
QV_schedDisable(3U); // <== disable scheduler up to given prio.
. . .
enum QStateRet QState
Type returned from state-handler functions.
Definition qp.h:212
Event class.
Definition qp.h:131
QSignal sig
Signal of the event (see Event Signal)
Definition qp.h:135
void QV_schedDisable(uint_fast8_t const ceiling)

◆ QV_schedEnable()

void QV_schedEnable ( void )
static

QV scheduler enable

Details
This function re-enables the QV scheduler previously disabled with QV_schedDisable().
Note
QV_schedEnable() must be called (typically from the system clock tick ISR) when the application ever uses QV_schedDisable().
See also
QV_schedDisable()
Usage
The following example shows how to enable the QV scheduler:
void SysTick_Handler(void) {
QTIMEEVT_TICK_X(0U, &l_SysTick_Handler); // time events at rate 0
QV_schedEnable(); // <== enable the scheduler to process next clock tick
. . .
#define QTIMEEVT_TICK_X(tickRate_, sender_)
Invoke the system clock tick processing QTimeEvt_tick_()
Definition qp.h:1238
void QV_schedEnable(void)
Definition qv.c:94

Definition at line 94 of file qv.c.

◆ QV_onIdle()

void QV_onIdle ( void )
static

QV idle callback (customized in BSPs for QV)

QV_onIdle() is called by the non-preemptive QV kernel (from QF_run()) when the scheduler detects that no events are available for active objects (the idle condition). This callback gives the application an opportunity to enter a power-saving CPU mode, or perform some other idle processing (such as QS software tracing output).

Attention
QV_onIdle() is invoked with interrupts DISABLED because the idle condition can be asynchronously changed at any time by an interrupt. QV_onIdle() MUST enable the interrupts internally, but not before putting the CPU into the low-power mode. (Ideally, enabling interrupts and low-power mode should happen atomically). At the very least, the function MUST enable interrupts, otherwise interrupts will remain disabled permanently.

Member Data Documentation

◆ QV_priv_

QV_Attr QV_priv_
private

Definition at line 75 of file qv.h.


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