I think that I should expand on the example with a bit of background.

I am sending a ring buffer via a synchronous FSK modem, the RxRdIdx is where I start reading from in the buffer the WrRdIdx is where I stop reading in the buffer (all available data will then be sent)

The function call is a call to the "getCharFromBuffer" which returns the character (obviously) but also increments the RxRdIdx by 1 so that it approaches the WrRdIdx.

After I receive the char from the function, I clock it out a bit at a time.

I have thought about just making a copy of RxRdIdx as I enter the function and then using this as a variable that I can do what I want with in the for loop, but it adds some dgree of uncertainty to the process (what if I Rx another byte from the serial port while I am clocking this data out, I would like to sent that new byte as well)

A while loop would probably not work, (nor would the >= clause in the for loop) as I am using a circular buffer which means that RxWrIdx may infact be less than the RxRdIdx.

Or could I do something like:

while(RxRdIdx != RxWrIdx)
{

}

Thanks for all the suggestions

Regards

Marshall