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How can we add port interfaces to the arguments in our C description? A hardware design exchanges data and 
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control commands with the rest of the system using ports with properly associated interfaces. Adding 
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interfaces to ports in an HLS description is the main concept introduced in this video.
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Hardware designs use ports to communicate with other modules on a system. Ports have their own hardware 
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structure and can be a simple wire or a complex circuits implementing an interface, realising its sophisticated
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protocol.
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Ports can be output, input or inout. 
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Each input, output or inout signal in the hardware can have its own dedicated port. Also, a group of signals 
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can collaborate in implementing a port. 
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The hardware ports can be as simple as one-bit binary wire to 8-bit parallel data bus to complex 
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serial buses such as USB, DDR memory access port, I2C access port, just to name a few.
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This code is the simple LED controller description explained in the previous lecture. The function 
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body is a simple assignment that returns a fixed value to drive eight LEDs. 
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We expect that a group of wires implements this assignment in the final hardware.  As function arguments 
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are synthesised into input/output signals in the corresponding hardware design, there should be a port 
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associated with each of them implementing a specific interface.
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In this example, the 8-bit width port implements eight simple wires without any specific protocol. 
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How can we define a port interface associated with a function argument in a C/C++ code?
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Compiler directives can help us to do this definition. 
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For this purpose, we use the pragma directive following by HLS then INTERFACE. 
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Then we should specify the interface. As we don’t have any specific interface
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in this example, the AP_NONE is used for this purpose. 
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Finally, we should indicate the function argument name. 
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Notice that, AP_NONE interface models a simple wire port in the final hardware design.
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In addition to the function argument interfaces, there is an interface assigned to the whole function 
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that should be defined using a compiler directive via pragma.
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This line of code describes the interface assigned to the whole function. 
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More details of this function level interface are explained along the course.
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After understanding the concept behind the HLS description of the simple LED controller,  “How can we use 
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Vivado-HLS to implement our controller?” In the following video, 
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I will cope with this question.
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These are the takeaway messages from this lecture.
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Compiler directives can be used to assign a hardware interface with a proper protocol to a function 
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description , The compiler directives can be applied to Function arguments, Or the function itself
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Now, the quiz question.
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How to describe a 16-LED controller in HLS that turns on the lower 8 LEDs and keeps the rest 
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OFF? 
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You can use the quiz question in the previous lecture, and add proper HLS pragmas to the code.