Description in VHDL is given by http://www.cs.sfu.ca/~ggbaker/reference/std_logic/src/std_logic_entities.vhd
Truth Table
DataIn | Clock | Reset | DataOut |
* | * | U | U |
* | * | 1 | 0 |
* | 0-Trns | 0 | NC |
* | 1-Trns | 0 | DataIn |
* | X-Trns | 0 | X or U or NC |
* | * | X | X or U or 0 or NC |
* = do not care U = L.'U' 0 = L.'0' or L.'L' 1 = L.'1' or L.'H' X = L.'X' or L.'W' or L.'Z' or L.'-' NC = no change Clock transition definitions: 1-Trns: 0 -> 1 0-Trns: ~ -> 0 or 1 -> * or X -> X|U or U -> X|U X-Trns: 0 -> X|U or X|U -> 1