QXSemaphore Class Reference

Counting Semaphore of the QXK preemptive kernel. More...

#include "qxk.h"

Public Member Functions
void	QXSemaphore_init (QXSemaphore *const me, uint_fast8_t const count, uint_fast8_t const max_count)
bool	QXSemaphore_wait (QXSemaphore *const me, QTimeEvtCtr const nTicks)
bool	QXSemaphore_tryWait (QXSemaphore *const me)
bool	QXSemaphore_signal (QXSemaphore *const me)

Private Attributes
QPSet	waitSet
uint8_t volatile	count
uint8_t	max_count

Detailed Description

Counting Semaphore of the QXK preemptive kernel.

QXSemaphore is a blocking mechanism intended primarily for signaling extended threads. The semaphore is initialized with the maximum count (see QXSemaphore_init()), which allows you to create a binary semaphore (when the maximum count is 1) and counting semaphore when the maximum count is > 1.

Usage

The following example illustrates how to instantiate and use the semaphore in your application.

QXSemaphore BTN_sema; // semaphore to signal a button press//
int main() {
    . . .
    // initialize the BTN_sema semaphore as binary, signaling semaphore//
    QXSemaphore_init(&BTN_sema, // pointer to semaphore to initialize//
                     0U,  // initial semaphore count (singaling semaphore)//
                     1U); // maximum semaphore count (binary semaphore)//
    . . .
}
 
void main_threadXYZ(QXThread * const me) {
    while (1) {
        . . .
        QXSemaphore_wait(&BTN_sema,  // <--- pointer to semaphore to wait on//
                         QXTHREAD_NO_TIMEOUT); // timeout for waiting//
        . . .
    }
}
 
void GPIO_Handler(void) {
    . . .
    QXSemaphore_signal(&BTN_sema); // <--- pointer to semaphore to signal//
    . . .
}

Definition at line 208 of file qxk.h.

Member Function Documentation

QXSemaphore_init()

void QXSemaphore_init	(	QXSemaphore *const	me,
		uint_fast8_t const	count,
		uint_fast8_t const	max_count
	)

QXSemaphore_wait()

bool QXSemaphore_wait	(	QXSemaphore *const	me,
		QTimeEvtCtr const	nTicks
	)

Definition at line 95 of file qxk_sema.c.

QXSemaphore_tryWait()

bool QXSemaphore_tryWait

(

QXSemaphore *const

me

)

Definition at line 182 of file qxk_sema.c.

QXSemaphore_signal()

bool QXSemaphore_signal

(

QXSemaphore *const

me

)

Definition at line 224 of file qxk_sema.c.

Member Data Documentation

waitSet

QXSemaphore::waitSet

private

Set of extended threads waiting on this semaphore

Definition at line 212 of file qxk.h.

count

QXSemaphore::count

private

Semaphore up-down counter

Definition at line 215 of file qxk.h.

max_count

QXSemaphore::max_count

private

Maximum value of the semaphore counter (e.g., 1 for binary semaphore)

Definition at line 218 of file qxk.h.

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

• qxk.h
• DOC-QPC-MAN/qxk.dox
• qxk_sema.c