Chapter 7. Improved I/O

Previous versions of VHDL provided fairly basic forms of binary and text I/O. In this chapter, we describe additions to the I/O and string conversion features provided by VHDL-2008.

The To_string Functions

In previous versions of VHDL, converting a value to a string required the use of the 'image attribute or the write procedures from the textio package. These options were very limiting. The 'image attribute was only defined for scalar types, and the write procedures were only defined for the predefined scalar types and for bit_vector. VHDL-2008 adds predefined to_string operations as a flexible alternative for string conversion. As a function, to_string is overloadable, supports scalar and composite types, and can have multiple ...

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