Verilog-2001 added the much-heralded @* combinational sensitivity list token. Although the

combinational sensitivy list could be written using any of the following styles:

always @*

always @(*)

always @( * )

always @ ( * )

or any other combination of the characters @ ( * ) with or without white space, the author prefers the first

and most abbreviated style. To the author, "always @*" clearly denotes that a combinational block of logic

follows.

The Verilog-2001 "always @*" coding style has a number of important advantages over the more

cumbersome Verilog-1995 combinational sensitivity list coding style:

·  Reduces coding errors - the code informs the simulator that the intended implementation is

combinational logic, so the simulator will automatically add and remove signals from the sensitivity

list as RTL code is added or deleted from the combinational always block. The RTL coder is no longer

burdened with manually insuring that all of the necessary signals are present in the sensitivity list. This

will reduce coding errors that do not show up until a synthesis tool or linting tool reports errors in the

sensitivity list. The basic intent of this enhancement is to inform the simulator, "if the synthesis tool

wants the signals, so do we!"

·  Abbreviated syntax - large combinational blocks often meant multiple lines of redundant signal

naming in a sensitivity list. The redundancy served no appreciable purpose and users will gladly adopt

the more concise and abbreviated @* syntax.

·  Clear intent - an always @* procedural block informs the code-reviewer that this block is intended to

behave like, and synthesize to, combinational logic.