Keyword: VARIABLE
The variable keyword declares a variable of a specified type.
A variable declaration includes—in this order—the reserved word "variable", the variable’s name, the variable’s subtype, and, optionally, an expression specifying the initial value of the variable.
A variable can only be declared within a process, procedure or function. Also, a variable cannot be of a file type. Variables declared within a process have their values preserved during subsequent executions of the process. Variables declared within a function or procedure have their values initialized each time the function or procedure is called.
Example
process(Rst,Clk)
variable Q: integer range 0 to 15;
begin
if Rst = '1' then -- Asynchronous reset
Q := 0;
elsif rising_edge(Clk) then
if Load = '1' then
Q := to_unsigned(Data); -- Convert vector to
-- integer
elsif Q = 15 then
Q := 0;
else
Q := Q + 1;
end if;
end if;
Count <= to_vector(4,Q); -- Convert integer to
-- vector
end process;
LRM
4.3
See also
