[Doc] Add a draft documentation about the bitstream setting

docs/source/manual/file_formats/bitstream_setting.rst

@@ -0,0 +1,27 @@
+.. _file_formats_bitstream_setting:
+
+Bitstream Setting (.xml)
+------------------------
+
+An example of bitstream settings is shown as follows.
+This can define a hard-coded bitstream for a reconfigurable resource in FPGA fabrics.
+
+.. code-block:: xml
+
+  <openfpga_bitstream_setting>
+    <pb_type name="<string>" source="eblif" content=".param LUT"/>
+  </openfpga_bitstream_setting>
+
+.. option:: pb_type="<string>"
+
+  The ``pb_type`` name to be constrained, which should be the full path of a ``pb_type`` consistent with VPR's architecture description. For example, ``pb_type="clb.fle[arithmetic].soft_adder.adder_lut4"``
+
+.. option:: source="<string>"
+
+  The source of the ``pb_type`` bitstream, which could be from a ``.eblif`` file. For example, ``source="eblif"``.
+
+.. option:: content="<string>"
+
+  The content of the ``pb_type`` bitstream, which could be a keyword in a ``.eblif`` file. For example, ``content=".attr LUT"`` means that the bitstream will be extracted from the ``.attr LUT`` line which is defined under the ``.blif model`` (that is defined under the ``pb_type`` in VPR architecture file).
+  
+.. warning:: Bitstream is a feature for power-users. It may cause wrong bitstream to be generated. For example, the hard-coded bitstream is not compatible with LUTs whose nets may be swapped during routing stage (cause a change on the truth table as well as bitstream). It is users's responsibility to ensure correct bitstream.

docs/source/manual/file_formats/index.rst

@@ -18,4 +18,6 @@ OpenFPGA widely uses XML format for interchangable files
 
    fabric_bitstream
 
+   bitstream_setting
+
    fabric_key

docs/source/manual/openfpga_shell/openfpga_commands/setup_commands.rst

@@ -56,6 +56,33 @@ write_openfpga_simulation_setting
 
     Show verbose log
 
+read_openfpga_bitstream_setting
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  Read the XML file about bitstream settings (see details in :ref:`file_formats_bitstream_setting`)
+
+  .. option:: --file <string> or -f <string>
+     
+    Specify the file name. For example, ``--file bitstream_setting.xml`` 
+
+  .. option:: --verbose
+
+    Show verbose log
+
+write_openfpga_bitstream_setting
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+  Write the OpenFPGA XML bitstream settings to a file
+
+  .. option:: --file <string> or -f <string>
+     
+    Specify the file name. For example, ``--file auto_bitstream_setting_echo.xml``.
+    See details about file format at :ref:`file_formats_bitstream_setting`.
+
+  .. option:: --verbose
+
+    Show verbose log
+
 link_openfpga_arch
 ~~~~~~~~~~~~~~~~~~