Stream oriented processing is an important methodology used in FPGA-based parallel processing. Characteristics of stream-oriented computing include high-data-rate flow of one or more data sources; fixed size, small stream payload tone byte to one word); compute-intensive operations, usually low precision fixed point, on the data stream; access to small local memories holding coefficients and other constants; and occasional synchronization between computational phases. In this paper we describe language constructs, compiler technology, and hardware/software libraries embodying the Streams-C system which has been developed to support stream-oriented computation on FPGA-based parallel computers. The language is implemented as a small set of library functions callable from a C language program. The Streams-C compiler synthesizes hardware circuits for multiple FPGAs as well as a multi-threaded software program for the control processor Our system includes a functional simulation environment based on POSIX threads, allowing the programmer to simulate the collection. of parallel processes and their communication at the functional level. Finally we present an: application written both in Streams-C and hand-coded in VHDL. Compared to the hand-crafted design, the Streams-C-generated circuit takes 3x the area and runs at 1/2 the clock rate. In terms of time to market, the hand-done design took a month to develop by an experienced hardware developer The Streams-C design took a couple of days, for a productivity increase of 10x.
