ROL — rotate left
q <= a ROL b;qequals arotated left by bbits. Instead of filling the right bbits with
a value, the bbits that were shifted off the left end are copied to the right
of the shifted abits. An array that originally contained ABCDand is
rotated left one bit will become BCDA.ROR — rotate right
q <= a ROR b;qequals arotated right by bbits. Instead of filling the left bbits with
a value, the bbits that were shifted off the right end are copied to the left
of the shifted abits. An array that originally contained ABCDand is
rotated right one bit will become DABC.
These operators can now be overloaded to work with user-defined types.Syntax Consistency
As part of the VHDL93 syntax update a number of the language end
clauses were modified to become more consistent. All of the clauses now
include the beginning clause identifier. For instance in VHDL87 the
entityclause was as shown here:ENTITY test IS
---
END test;In VHDL93 the same construct can optionally look as follows:ENTITY test IS
---
END ENTITY test;Notice that the END clause contains the starting ENTITY clause.
Including the keyword ENTITYin the ENDclause is optional but allowed in
VHDL93. The same holds true for the architecture,package,package
body, configuration, component, block, process, record, case, if,
procedure, and generatestatement. Examples are shown here:464 Appendix D: VHDL93 Updates