VHDL composite types consists of arrays and records. Each
object of this data type can hold more than one value.
Arrays consist of many similar elements of any data type,
including arrays. The array is declared in a TYPE
statement. There are numerous items in an array declaration. The
first item is the name of the array. Second, the range of the array
is declared. The keywords TO and DOWNTO designate ascending or
descending indices within the specified range, respectively. The
third item in the array declaration is the specification of the data
type in each element of the array.
In the example above, an array consisting of 32 bits is
specified. Note that individual elements of the array are accessed by
using the index number of the element as shown above. The index
number corresponds to where in the specified range the index appears.
For example, X(12) above refers to the thirteenth element from
the left (since the leftmost index is 0) in the array.
