C Language for FPGA-Based Hardware Design?
Let's think a bit more about the role of Cor lack of a role, as the case may bein hardware design. Why is standard C not appropriate as a replacement for existing hardware design languages? Because any good programming language provides one important thing: a useful abstraction of its target. VHDL and Verilog (or, more precisely, the synthesizable
The standard C language does not provide that level of abstraction (which we call register transfer level, or RTL), so "C-based" languages for hardware could add RTL-like constructs in the form of syntax decorations, extra functions or keywords, compiler hints, and more to create some meaningful way of
So why use C at all for FPGA design? There are significant advantages, including the potential for hardware-software codesign, for the creation of test benches written in C, and (if the modified C language supports it) the ability to compile and debug an FPGA application using a standard C development environment. And if a mid-level approach to hardware abstraction is takenone that does not require that the programmer understand all the details of the hardware target, and yet is guided by the programming model toward more appropriate
Compelling Platforms for Software Acceleration
Here's where software developers come in. On the applications side there is an increasing trend toward using FPGAs as hardware accelerators for high-performance computing. Applications that demand such performance exist in many domains, including communications, image processing, streaming media, and other general-purpose signal processing. Many of these applications are in the embedded software space, while others represent scientific, biomedical, financial, and other larger-scale computing solutions.
When acceleration is required, these applications typically begin their lives as software models, often in C language, and are then manually rewritten and implemented in hardware using VHDL or Verilog. This manual conversion of software algorithms to hardware is a process that can be long and
On the hardware side, there have been recent advances in FPGA-based programmable platforms that make FPGAs even more practical for use as application accelerators. In fact, FPGAs with embedded processor cores have now become
From a tools perspective, what is interesting about these new devicesand the new computing platforms they representis that they are flexible enough to support the use of
It is here that FPGA designers who are questioning the use of software design languages and methods for FPGAs may be missing the point. C is not likely to replace HDLs such as VHDL and Verilog for traditional, general-purpose hardware design. C will, however, play a strong role in the kind of mixed hardware/software applications that are emerging todayapplications in which the line between what is software and what is hardware is becoming increasingly blurred, and where the ability to
In addition, because of the prevalence of embedded FPGA processors, the C language is already being used for FPGAs by thousands of software engineers. The problem is that the vast majority of these software