PipelineC

A C-like(1) hardware description language (HDL)(2) adding HLS(high level synthesis)-like automatic pipelining(3) as a language construct/compiler feature.

  1. Not actually regular C. But mostly compileable by gcc for doing basic functional verification/'simulation'.
    This is for convenience as a familiar bare minimum language prototype, not as an ideal end goal. Reach out to help develop something more complex together!
  2. Can reasonably replace Verilog/VHDL. Compiler produces synthesizable and human readable+debuggable VHDL. Hooks exist for inserting raw VHDL / existing IP / black boxes.
  3. If a computation can be written as a pure function without side effects (i.e. no global/static variables) then it will be autopipelined.
    Conceptually similar to technologies like Intel's variable latency Hyper-Pipelining
    and Xilinx's retiming options.
    Sharing some of the compiler driven pipelining design goals of Google's XLS Project and the DFiantHDL language as well.

What is PipelineC not?

  • High level synthesis of arbitrary C code with a global memory model / threads / etc.
  • Meta-programming hardware-generator (ex. uses C type system and preprocessor).

Core Features/Benefits

An easy to understand hardware description language centered around pipelining

  • Automatic pipelining as a feature of the compiler. Basic use of the tool is to generate single pipelines to drop into existing designs. Eliminate the practice of pipelining logic by hand = not portable (relies on operating frequency and part).
  • Helpful timing feedback derived from synthesis tool reports to help identify critical path logic that cannot be automatically pipelined.
  • Simulate your code in seconds, debug with printf's (ex. tool imports human readable+debuggable VHDL into Modelsim)
  • Compose complex portable designs consisting of multiple pipelines and controlling state machines.
  • Can start by cloning existing VHDL/Verilog designs or including raw VHDL as a starting point - not forced to use automatic pipelining features - a full hardware description language replacement.
  • Familiar C function syntax that eliminates many HDL quirks that beginners (and experts) can fall victim to (ex. blocking/nonblocking assignments).
  • Globally visible point-to-point wires/clock crossings and inferred clock enables make composing complex module hierarchies / state machines easier.
  • Integrates with software side C easily; helpful built in code generation. (ex. for un/packing structs from de/serialized byte arrays).

Fundamental design elements are state machines, pipelines, and interconnects (wires,cdc,fifos,etc).

By isolating complex logic into autopipelineable functions, and only writing literal clock by clock hardware description when absolutely necessary, PipelineC designs do not need to be rewritten for each new target device / operating frequency. The hope is to build shared, high performance, device agnostic, hardware designs described in a somewhat familiar C language look.

For software folks I want writing PipelineC to feel like solving a programming puzzle in C, not a whole new paradigm of programming languages.
The rules of the puzzle hide/imply hardware concepts. For hardware folks I want PipelineC to be a better hardware description language.

Currently Supported Tools (tested on Linux):
Synthesis: Xilinx Vivado, Intel Quartus, Lattice Diamond, GHDL+Yosys+NextPNR
Simulation: Modelsim

GitHub

https://github.com/JulianKemmerer/PipelineC