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One of the requirements during design simulation is the ability to print variables on the screen. For
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this purpose, a C/C++ code usually uses the printf function or cout object. In this lecture, 
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I will explain how to use these functions in HLS.
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Vivado HLS supports printing values that require more than 64-bits to represent. 
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The printing functions are not synthesizable and only should be used during C-Simulation.
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The easiest way to output any value stored in an arbitrary precision variable is to use the C++ standard 
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output stream. For this purpose, the #include <iostream> or <iostream.h> header file should be added 
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to the test-bench file. The C++ modifiers std::oct, std::dec, std::hex 
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can be used to format the printed value.
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It is also possible to use the standard C library (#include <stdio.h>) to print out values larger than 64-bits.  For this purpose, 
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Firstly, convert the value to a C++ std::string by using the to_string() member function provided
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by the arbitrary precision class template. And then convert the result to a null-terminated C character 
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string by using the c_str() method.
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The arbitrary precision integer template class provides a member function, called to_string 
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to convert the value into the corresponding C++ string. This function gets an optional argument that 
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determines the output radix.
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Working with a multi-bit data type in a hardware design usually needs direct access to the bits in 
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the corresponding variables. HLS provides a set of functions for bit-level manipulation, which is 
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the subject of the next lecture.
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These are our takeaway messages. Vivado HLS supports printing values that require more than 64-bits 
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to represent. The member function, called to_string, converts the value of an arbitrary 
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precision integer data types into the corresponding C++ string.
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Now the quiz question. What is the output of this code?