Std logic vector

FUNCTION To.StdLogicVector (b BIT VECTOR ) RETURN std logic vector ... 

FUNCTION To.UXO I ( s std logic vector) RETURN std logkuvector. FUNCTIONTo UXOI (s std ulogic vector) RETURN std ulogic vector,... 

The std Jogic type is the resolved form of the std ulogic type and is well supported by the functions and operators declared in the IEEE library package STD LOGIC l 164. The stdJoglc vector is the array form of the type. This package must therefore be visible to each design file in the sequence follower. 

The first stage is to select the libraries that the design is to use. The basic libraries and packages that are available to a VHDL designer have been discussed in Chapter 3. This example uses objects of type BIT and BIT VECTOR, and executes basic logic operations. It therefore only requires the STD library with its STANDARD package. As these are implicitly visible to every design unit. Library and Use clauses are not required. 

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