The design of cyber-physical systems (CPSs) remains challenging because of their highly heterogeneous nature that makes modeling, design and analysis hard. Despite extensive work in model-based approaches, few unified co-simulation tools are available today for such systems. This paper proposes a simulation strategy that benefits from the availability of recent FPGA platforms and advances in the high-level synthesis (HLS). Our proposal consists in using HLS to build a CPS simulator running at high-speed on a FPGA; in this view, HLS is used to synthesize the embedded systems in addition of the physical environment of the CPS, which are jointly emulated on the FPGA. Our paper proposes a case study illustrating this approach: the simulation of the automatic identification system required in maritime communications. The simulation executed on the latest FPGA generation is accelerated by a factor x811 compared to software alternatives demonstrating that FPGAs exhibit appealing characteristics for CPS simulations.