util/reggen/README.md

# Register generator `reggen` and `regtool`

The utility script `regtool.py` and collateral under `reggen` are Python
tools to read register descriptions in Hjson and generate various output
formats. The tool can output html documentation, standard json, compact
standard json (whitespace removed) and Hjson.  The example commands assume
`$REPO_TOP` is set to the toplevel directory of the repo.

### Setup

If packages have not previously been installed you will need to set a
few things up. First use `pip3` to install some required packages:

```console
$ pip3 install --user hjson
$ pip3 install --user mistletoe
$ pip3 install --user mako
```

### Register JSON Format

To ensure things stay up to date, the register json format information
is documented by the tool itself. Documentation can be generated by
running the tool to produce markdown and processing that into html.
This information can also be found in the
[register tool documentation](../../doc/rm/register_tool.md).
This references features in the [docgen](../docgen/README.md) suite
of documentation scripts.

```console
$ cd $REPO_TOP/util
$ ./regtool.py --doc | ./docgen.py -c > /tmp/outdoc.html
```

### Examples using standalone regtool

Normally for documentation the `docgen` tool will automatically use
`reggen`. See the examples in the `docgen` documentation tree.

The script `regtool.py` provides a standalone way to run `reggen`.
Note that the same example inputs are used here as for `docgen`.

This generates html from the register description and is verbose. Since
embeddable html is generated, the css is not included, so the output will
not be perfectly formatted.

```console
$ cd $REPO_TOP/util
$ ./regtool.py -v -d docgen/examples/uart.hjson > /tmp/outuart.html
```

The following shows an example of how to generate the full featured
standard json from the register description Hjson file:

```console
$ cd $REPO_TOP/util
$ ./regtool.py -v -j docgen/examples/uart.hjson > /tmp/outuart.json
```

The following shows an example of how to generate RTL from a register
description:

```console
$ cd $REPO_TOP/util
$ mkdir /tmp/rtl
$ ./regtool.py -r -t /tmp/rtl ../hw/ip/uart/data/uart.hjson
$ ls /tmp/rtl
    uart_reg_pkg.sv   uart_reg_top.sv
```

The following shows an example of how to generate a DV UVM class from
a register description:

```console
$ cd $REPO_TOP/util
$ mkdir /tmp/dv
$ ./regtool.py -s -t /tmp/dv ../hw/ip/uart/data/uart.hjson
$ ls /tmp/rtl
    uart_reg_block.sv
```

If the target directory is not specified, the tool creates the DV file
under the `hw/ip/{module}/dv/` directory.