OpenFPGA/docs/source/manual/file_formats/bus_group_file.rst

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.. _file_format_bus_group_file:
Bus Group File (.xml)
=====================
The bus group file aims to show
- How bus ports are flatten by EDA engines, e.g., synthesis.
- What are the pins in post-routing corresponding to the bus ports before synthesis
An example of file is shown as follows.
.. code-block:: xml
<bus_group>
<bus name="i_addr[0:3]" big_endian="false">
<pin id="0" name="i_addr_0_"/>
<pin id="1" name="i_addr_1_"/>
<pin id="2" name="i_addr_2_"/>
<pin id="3" name="i_addr_3_"/>
</bus>
</bus_group>
Bus-related Syntax
------------------
.. option:: name="<string>"
The bus port defined before synthesis, e.g., addr[0:3]
.. option:: big_endian="<bool>"
Specify if this port should follow big endian or little endian in Verilog netlist. By default, big endian is assumed, e.g., addr[0:3].
Pin-related Syntax
------------------
.. option:: id="<int>"
The index of the current pin in a bus port. The index must be the range of **[LSB, MSB-1]** that are defined in the bus.
.. option:: name="<string>"
The pin name after bus flatten in synthesis results