A C++ template library for embedded applications
MIT licensed
Designed and
maintained by
John Wellbelove
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Tutorial

Locked Queues



There are several lockable queues in the ETL.
Each offers a different method of locking and unlocking a queue for modification.

____________________________________________________________________________________________________
queue_spsc_isr


template <typename T, size_t SIZE, typename TAccess>
class queue_spsc_isr

This queue was originally designed for use with an Interrupt Service Routine (ISR), where functionality would be provided to it to enable and disable interrupts. This is achieved in this queue by supplying a template parameter type that implements two static functions;

lock()
unlock()


The first disables the relevant interrupts and the second enables them.
The queue, of course, is not limited to just interrupts.
____________________________________________________________________________________________________
Example
struct InterruptControl
{
 
static void lock()
  {
    OsDisableInterrupts();
  }

 
static void unlock()
  {
    OsEnableInterrupts();
  }
};

etl::
queue_spsc_isr<char, 100, InterruptControl> charQueue;
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queue_spsc_locked


template <typename T, size_t SIZE>
class queue_spsc_locked

This queue is similar to the above, but the access control functions are supplied at run time as references to etl::ifunction.
____________________________________________________________________________________________________
Example
void QueueLock()
{
  OsDisableInterrupts();
}

void QueueUnlock()
{
  OsEnableInterrupts();
}

etl::
function_fv<QueueLock>   queueLock;
etl::
function_fv<QueueUnlock> queueUnlock;

etl::
queue_spsc_isr<char, 100> charQueue(queueLock, queueUnlock);
____________________________________________________________________________________________________
queue_spsc_lockable


template <typename T, size_t SIZE>
class queue_spsc_lockable

This queue provides access to locking by providing two pure virtual functions, lock() and unlock() that the user of the queue must supply implementations for.
____________________________________________________________________________________________________
Example
class QueueInt : public etl::queue_lockable<int, 4>
{
public:

  QueueInt()
  {
  }

 
void lock() const override
  {
    OsDisableInterrupts();
  }

 
void unlock() const override
  {
    OsEnableInterrupts();
  }
};

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