Synthesis from C and other programming languages.

The advantages of using a general-purpose language to describe both hardware and software are becoming apparent: designs can be ported easily and tested in software environments before implementation in hardware. There is also the potential benefit that software engineers can be used to generate ASICs: they are normally cheaper to employ than ASIC engineers! The practical benefit of such approaches is not fully proven, but there is great potential.

The software programming paradigm, where a serial thread of execution runs around between various modules is undoubtedly easier to design with than the forced parallelism of expressions found in RTL-style coding. Ideally, a new thread should only be introduced when there is a need for concurrent behaviour in the expression of the design. A product from »COMPILOGIC is typical and claimed the following:

• Compile C to RTL Verilog for synthesis to FPGA and ASIC hardware.
• Compile C to Test-Bench for Verilog simulation.
• Compiler options to control design's size and performance.
• Global analysis optimizes C-program intentions in hardware.
• Automatic and controlled parallelism and pipelining.
• Generates readable Verilog for integration and modification.
• Options to assist tracing/debugging HDL generated.
• Includes command line and GUI programmer's workbench.

However, we cannot compile general C/C++ programs to hardware: they tend to use too many language features. Java and CSharp are better, owing to stronger typing and banning of arithmetic on object handles (all subscription operations apply to first-class arrays).

Must be finite state:

• all recursion bounded, otherwise we have unknown stack space use,
• all dynamic storage allocation outside of infinite loops, or at least also freed inside the same loops (needs advanced heap shape analysis as currently being developed here in Cambridge),
• perhaps use only boolean logic and integer arithmetic, although in principle floating point can be compiled to hardware without problem,
• limited string handling (most string handling packages rely on garbage collection),
• very limited standard library support because there is no operating system present to provide most of the services.