Synthesis problems with while and non-constant terminal point.

You need to get used to thinking in terms of hardware, instead of how many times something will loop.

Think about how you would build it using TTL gates and flip-flops, for example. Once you do that, consider what your loop is doing. Making things run fast in hardware means doing many things in parallel. C style loops don't naturally do that.

Hope this helps,

-- glen

Consider adding a clock input and use a synchronous process loop that executes once per clock.

Now, within this process, you can do as many sequential statements as you like up to the limit of the clock cycle time. A static timing analysis can check this for you after synthesis.

Step one is to get your code running synchronously and correctly in a simulation testbench.

Step two is a trial synthesis and static timing check.

If static timing fails the FMAX constraint, modify your code to do less per clock, or reduce the clock frequency.

Good luck.

-- Mike Treseler