Software-defined radio (SDR) brings the flexibility of software to the domain of wireless protocol design, promising an ideal platform both for research and innovation and the rapid deployment of new protocols on existing hardware. However, existing SDR programming platforms require either careful hand-tuning of low-level code, negating many of the advantages of software, or are too slow to be useful in the real world. In this demo we present Ziria, the first software-defined radio programming platform that is both easily programmable and performant. Ziria introduces a novel programming model tailored to wireless physical layer tasks and captures the inherent and important distinction between data and control paths in this domain. We show the capabilities of Ziria by demonstrating a real-time implementation of WiFi PHY running at 20 MHz.