Getting started


The latest release version of hdl-registers can be installed from PyPI with the command

python3 -m pip install hdl-registers

Alternatively, you can clone the git repository if you want to use a development version. From the repo checkout you can install the Python package by running

python3 -m pip install .

in the repo root. You can also access it in your scripts by adding the repo path to the PYTHONPATH environment variable, or by modifying sys.path in your script.


A minimal usage example:

from pathlib import Path

from hdl_registers.generator.vhdl.register_package import VhdlRegisterPackageGenerator
from hdl_registers.parser.toml import from_toml

this_dir = Path(__file__).parent

register_list = from_toml(name="caesar", toml_file=this_dir / "caesar_registers.toml")
VhdlRegisterPackageGenerator(register_list=register_list, output_folder=this_dir).create_if_needed()

The basis of all register operations is the RegisterList class, which represents a register map, meaning, the registers of one module. An object of this type is returned when calling from_toml() on a TOML file with the correct format. To try things out you could use the register TOML data from the TOML format example.

Register code generation is then done using one of the generator classes, for example VhdlRegisterPackageGenerator as seen in the example above. See the sidebar under “Code Generators” for information on what can be generated and how to invoke it.

If you have more than one module with registers in your project then these are represented with a RegisterList object each. See Scope for a background on this.

Integration in tsfpga

The tsfpga project, which is a sister project of hdl-registers, integrates register code generation in an elegant way. If a file named regs_<name>.toml is placed in the root of a module, and <name> matches the name of the module, it will be parsed and used as that module’s register map. In the simulation and build scripts there is then a call to the VHDL generators for each register list before each run. This makes sure that an up-to-date register definition is always used.

This is a good example of how hdl-registers can be used in an effective way.