pulsar

Pulsar is a programming language for building hardware accelerators with zero-latency memory access, which is achieved by:

1. Disallowing data-dependent addressing
2. Requiring all root control to have fully-resolved static timing

The language is currently under development, but a significant portion is functional. Here's an example of what it will be able to do once feature-complete:

struct Complex {
    re: Double,
    im: Double
}

func fft<FFT_SIZE>(input: Complex[FFT_SIZE], twid: Complex[FFT_SIZE / 2]) -> (output: Int) {
    for log in 0 ..< LOG2_FFT_SIZE {
        let span = FFT_SIZE >> (log + 1)
        for odd in span ..< FFT_SIZE {
            let odd = odd | span
            let even = odd ^ span
            let temp = input[even].re + input[odd].re
            ---
            input[odd].re = input[even].re - input[odd].re
            ---
            input[even].re = temp
            // ...
        }
    }
}

Introduction

You can declare hardware modules with the func keyword, specifying inputs and outputs. Types include primitive integers, structs, and (multi-dimensional) arrays. A struct cannot contain an array.

Operations which depend on each other or correspond to sequential logic must be gated between dividers (---). For example, a divider must be placed after multiplication but does not need to be placed after addition (which is purely combinational).

A lot of care has been put into good error messages. To quote the developers of spade,

Bad error messages are considered a bug. Please report them!

Crates

• pulsar-lang: Compiler driver
• pulsar-utils: Utilities for the pulsar-* crates
• pulsar-frontend: Parser/AST and type checking
• pulsar-ir: IR definition and optimization
• pulsar-backend: Target emission, e.g., Verilog (via calyx)
• calyx-builder: API for building calyx IR

License

Pulsar is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

Pulsar is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

A copy of the GNU General Public License, version 3, can be found in the LICENSE file.