.. _set_argument_interface_type:

set_argument_interface_type
----------------------------

This parameter specifies the interface type for the top-level interface.
This can be used to specify a pointer argument for a single element (single-element array or a single-element global variable) passed into the top-level function to become a simpler wire/register interface.
``set_argument_interface_type data_out register/wire``

A global variable can also be specified to become an AXI slave interface.
``set_argument_interface_type slave_memory axi_s``

For a single-element array/global variable passed in as argument to top-level function, there can be 5 different types of interface. 
1. If element is read from and written to, LegUp creates readdata, write_enable, writedata ports (default behaviour). 
2. If element is read-only, only readdata port is created (default behaviour)
3. If element is write-only, write_enable and writedata ports are created (default behaviour)
4. If element is write-only, and user wants the written data registered inside the top-level module so that the written data at the top-level interface is held constant, set_argument_interface_type <arg_name> register can be used. This creates only writedata ports at the top-level interface, which is connected to the output of the instantiated register in the top-level module.
5. If element is write-only, and user wants only the writedata port at the top-level interface without written data being registered (wire connection directly to the top-level), set_argument_interface_type <arg_name> wire -always_valid can be used.

Category
+++++++++

HLS Constraints

Value Type
+++++++++++

+--------------------+------------+
| Parameter          | Value Type |
+====================+============+
| argument_name      | String     |
+--------------------+------------+
| interface_type     | String     |
+--------------------+------------+

Valid Values
+++++++++++++

Three types of interface can be specified, "wire", "register", and "axi_s".

Dependencies
+++++++++++++

Require top-level function to be set via ``set_custom_top_level_module``. 

Applicable Flows
+++++++++++++++++

All devices for pure hardware flow

Test Status
++++++++++++

Actively in-use

Examples
+++++++++

    ``set_argument_interface_type data_out register``
data_out is a write-only single-element pointer argument passed into the top-level function. A register will be created at the top-level module to flop the written data for data_out. The output of the register is connected to the data_out writedata port at the top-level interface. 
    
    ``set_argument_interface_type data_out wire -always_valid``
data_out is a write-only single-element pointer argument passed into the top-level function. Only the writedata port will be created at the top-level for data_out. 

    ``set_argument_interface_type slave_memory axi_s``
slave_memory is a global variable specified to be an AXI slave interface.     

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