Protocols¶

Protocols in FlooGen define the communication interfaces used by endpoints and routers within the network. Currently, FlooGen primarily supports the AXI4 protocol. These definitions determine the properties of the interface, such as data width, address width, and ID width, which are then used to generate the corresponding SystemVerilog typedefs and structs.

Configuration¶

Protocols are defined under the protocols list in the configuration file. Each entry specifies a configuration that can be referenced by endpoints and routers.

Parameters¶

Parameter	Type	Description	Required	Default
`name`	String	Unique identifier for the protocol. Used to reference it in endpoint configurations.	Yes	-
`protocol`	String	The protocol standard. Must be set to `"AXI4"`.	Yes	-
`data_width`	Integer	Width of the data bus in bits.	Yes	-
`addr_width`	Integer	Width of the address bus in bits.	Yes	-
`id_width`	Integer	Width of the ID signals in bits.	Yes	-
`user_width`	Int / Map	Configuration for the AXI User signal. Can be a single integer (total width) or a map defining fields.	No	`1`
`type`	String	Sub-type classification, useful for heterogeneous networks (e.g., `"narrow"`, `"wide"`).	No	`None`
`type_prefix`	String	Prefix for generated SystemVerilog types. Set to `null` or empty to remove default.	No	`"axi"`
`description`	String	Optional description of the protocol.	No	`""`

Examples¶

Basic AXI4 Configuration¶

A standard AXI4 configuration with 64-bit data and 48-bit address width.

protocols:
  - name: "axi_std"
    protocol: "AXI4"
    data_width: 64
    addr_width: 48
    id_width: 4

Custom User Fields¶

The user_width parameter supports structured definitions. Instead of a single integer, you can provide a dictionary of field names and their bit widths. FlooGen will generate a packed SystemVerilog struct for these fields.

protocols:
  - name: "axi_custom_user"
    protocol: "AXI4"
    data_width: 64
    addr_width: 48
    id_width: 4
    user_width:
      qos: 4
      region: 4
      parity: 1

Heterogeneous Networks¶

For networks that mix different link types (e.g., a "narrow" control plane and a "wide" data plane), you can use the type field. This helps match endpoints to the correct network interfaces.

protocols:
  - name: "narrow_in"
    type: "narrow"
    protocol: "AXI4"
    data_width: 64
    addr_width: 48
    id_width: 4

  - name: "wide_in"
    type: "wide"
    protocol: "AXI4"
    data_width: 512
    addr_width: 48
    id_width: 6

Customizing Type Names¶

By default, FlooGen generates SystemVerilog types with an axi prefix (e.g., axi_<name>_req_t). You can customize this using type_prefix. To remove the prefix entirely (e.g., to avoid axi_axi_...), leave the value empty.

protocols:
  - name: "noc_link"
    protocol: "AXI4"
    data_width: 64
    addr_width: 48
    id_width: 4
    type_prefix: "floo" # Results in floo_noc_link_req_t