HIRL (working name: Hardware Intermediate Representation Language) is a proof-of-concept, declarative hardware description language optimized for RTL coding, aiming to provide modern Rust-like syntax and more restrictive semantics protecting the user from typical errors.
Notable features:
- Syntax inspired by Rust and C++
- Sensitivity semantics in the type system provide basic CDC validation
- Restrictive signal width and signedness semantics
- Bi-directional type deduction - not all types need to be explicitly specified in assignments
- No implicit conversions - potentially harmful implicit conversions are not allowed
- Generic constructs compiled to equivalent generic System Verilog code
- Builtin elab phase ensuring proper use of signals (i.e. no double drivers, no dangling inputs etc.)
- Interoperability with System Verilog
This section presents some basic code examples. More code samples can be found in the tests directory.
// Interface definition
module full_adder {
// All inputs and outputs are asynchronous
input async a;
input async b;
input async cin;
output async cout;
output async q;
}
// Module logic
impl full_adder {
cout = (a & b) | (cin & (a ^ b));
q = a ^ b ^ cin;
}module simple_counter{
// Clock input
input clock clk;
// Asynchronous reset signal (active low)
input async wire nreset;
// Combinational enable signal (clock domain is clk)
input comb(clk) wire enable;
// Synchronous 16-bit output bus
output unsigned sync(clk) bus<16> data;
}
impl simple_counter {
// data is 16 bits wide, 1u1 is 1 bit wide.
// Addition result is 17-bit and therefore needs
// to be explicitly truncated with trunc() builtin function
bus<16> counter_next = trunc(data + 1u1);
// Register storing counter's value
reg counter{
clk, // Auto-connected to `clk`
nreset, // Auto-connected to `nreset`
en: enable, // Enable the register with `enable` signal
next: counter_next, // Next value for the register
data, // Output is auto-connected to `data`
};
}Use Cargo for building. The compiler has builtin command line help. For practical example of use please also see this Makefile.
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