Scripting in Yosys
------------------

.. todo:: check logical consistency

Yosys reads and processes commands from synthesis scripts, command line
arguments and an interactive command prompt. Yosys commands consist of a command
name and an optional whitespace separated list of arguments. Commands are
terminated using the newline character or a semicolon (;). Empty lines and lines
starting with the hash sign (#) are ignored. See :ref:`sec:typusecase` for an
example synthesis script.

The command :cmd:ref:`help` can be used to access the command reference manual,
with ``help <command>`` providing details for a specific command.  ``yosys -H``
or ``yosys -h <command>`` will do the same outside of an interactive prompt.
The entire reference manual is also available here at :doc:`/cmd_ref`.

Example commands
~~~~~~~~~~~~~~~~

Commands for design navigation and investigation:

.. code-block:: yoscrypt

    cd                   # a shortcut for 'select -module <name>'
    ls                   # list modules or objects in modules
    dump                 # print parts of the design in RTLIL format
    show                 # generate schematics using graphviz
    select               # modify and view the list of selected objects

Commands for executing scripts or entering interactive mode:

.. code-block:: yoscrypt

    shell                # enter interactive command mode
    history              # show last interactive commands
    script               # execute commands from script file
    tcl                  # execute a TCL script file

Commands for reading and elaborating the design:

.. code-block:: yoscrypt

    read_rtlil           # read modules from RTLIL file
    read_verilog         # read modules from Verilog file
    hierarchy            # check, expand and clean up design hierarchy


Commands for high-level synthesis:

.. code-block:: yoscrypt

    proc                 # translate processes to netlists
    fsm                  # extract and optimize finite state machines
    memory               # translate memories to basic cells
    opt                  # perform simple optimizations


Commands for technology mapping:

.. code-block:: yoscrypt

    techmap              # generic technology mapper
    abc                  # use ABC for technology mapping
    dfflibmap            # technology mapping of flip-flops
    hilomap              # technology mapping of constant hi- and/or lo-drivers
    iopadmap             # technology mapping of i/o pads (or buffers)
    flatten              # flatten design

Commands for writing the results:

.. code-block:: yoscrypt

    write_blif           # write design to BLIF file
    write_btor           # write design to BTOR file
    write_edif           # write design to EDIF netlist file
    write_rtlil          # write design to RTLIL file
    write_spice          # write design to SPICE netlist file
    write_verilog        # write design to Verilog file


Script-Commands for standard synthesis tasks:

.. code-block:: yoscrypt

    synth                # generic synthesis script
    synth_xilinx         # synthesis for Xilinx FPGAs


Commands for model checking:

.. code-block:: yoscrypt

    sat                  # solve a SAT problem in the circuit
    miter                # automatically create a miter circuit
    scc                  # detect strongly connected components (logic loops)

Selections intro
~~~~~~~~~~~~~~~~

Most commands can operate not only on the entire design but also specifically on
selected parts of the design. For example the command :cmd:ref:`dump` will print
all selected objects in the current design while ``dump foobar`` will only print
the module ``foobar`` and ``dump *`` will print the entire design regardless of
the current selection.

.. code:: yoscrypt

	dump */t:$add %x:+[A] */w:* %i

The selection mechanism is very powerful. For example the command above will
print all wires that are connected to the ``\A`` port of a ``$add`` cell.
Detailed documentation of the select framework can be found under
:doc:`/using_yosys/more_scripting/selections` or in the command reference at
:doc:`/cmd/select`.