There is a far distance between computer simulation and hardware implementation of fast inline processing algorithms. This gets even harder when applying such an advanced technology as FPGA, with its benefits of speed and reliability but also caveats like unfamiliar development approaches, integer math and even hours of compilation time. We managed to bypass the complexity of tools by using LabVIEW FPGA and National Instruments hardware platform to rapidly implement control and demodulation functionality into a mock-up of a Fiber Optic Current Sensor. It was a great leap to get an alpha-prototype working in the lab with its parameters exceeding the best industry solutions. However, this implementation needed a plenty of work ahead to implement our ideas, debug and polish algorithms and ensure reliability. And that was the point where we got stuck with minor changes in the code and then hours of compilation to find out that we did wrong. Due to the rapidness of the process in fiber-optic scheme no other implementation could handle real-time processing so we were ought to put up with the delays. Finally, we convinced that this was the dead end. So, we put our efforts to create a reliable simulation model of the optical scheme of current sensor with the same LabVIEW tools. Succeeding in it, we applied our FPGA integer and fixed-point math to the desktop environment. This worked simply great, so we were able to run plenty of experiments, making changes and trying new ideas in real time in the form, that could be seamlessly moved to hardware FPGA-based platform. The article discloses several of our experiment results with the computer simulation correlated to the real-world measurements acquired with the mock-up.