Hi Chuck,
Ok that's good. If you are happy with the performane you can stop obviously.
If not you could try inlining the sqrtf function.
The optimization I referenced in the TI compiler would be much faster. It wouldn't have the function call and it wouldn't do the check for negative input value like the code does above. (I believe that's what the BMI is ... branch if minus)..
Anyway, that's not the default behaviour for the TI compiler, but if you can guarantee that your inputs are positive then you could use it. In your case you could probably take the sqrt of the abs of amplitude and this would guarantee you are not giving a negative number to SQRT. It might be faster that way than having the check for negative ... VABS is 1 cycle plus 1 cycle of result latency so I think it would be faster...