EnterCritical and LeaveCritical

[wmjenkinson]

Do these functions over complete protection during interrupts?

Thanks, Ireland.

[rsta2]

EnterCritical([IRQ_LEVEL]) ensures, that an IRQ cannot occur on the core, where it was called. An FIQ can still occur, but not when you call EnterCritical(FIQ_LEVEL). LeaveCritical() ends this. With multi-core support you should use spin locks instead. Please see this for more info!

[wmjenkinson]

I tried replacing the "enter critical and leave critical" functions with spinlocks but that doesn't work. Could you provide me with an example?

`char CSoftSerialDevice::OutBuf (void)
{
EnterCritical ();

if (m_nInPtr == m_nOutPtr)
{
	LeaveCritical ();

	return 0;
}

char chChar = m_Buffer[m_nOutPtr];

m_nOutPtr = (m_nOutPtr+1) & BUFMASK;

LeaveCritical ();

return chChar;

}`

[rsta2]

Replace EnterCricital() with m_SpinLock.Acquire() and LeaveCritical() with m_SpinLock.Release(). Furthermore you have to add CSpinLock m_SpinLock; to the class declaration, where the spin lock is used in. CSpinLock is defined in <circle/spinlock.h>, which has to be included into the header file of your class. That's all.

Please note, that you have to configure the project for multi-core support, so that it really uses spin locks. Otherwise it will use EnterCritical() again, because its faster and spin locks are only required with multiple cores.