LUT_INPUT Primitive
LUT_INPUT
buffer specifies a LUT
function. The LUT_INPUT
buffer marks input signals for a
LUT_OUTPUT
buffer. The logical functionality of the
LUT_INPUT and LUT_OUTPUT
buffers is a simple wire, but
together they identify LUT boundaries.
To make a LUT, you need to use both input and output buffers that bound a cone of logic, as in the following example.
FUNCTION lut_output (in) RETURNS (out);
FUNCTION lut_input (in) RETURNS (out);
SUBDESIGN test
(
ina : INPUT ;
inb : INPUT ;
inc : INPUT ;
ind : INPUT ;
outd : OUTPUT ;
)
BEGIN
outd = lut_output(
lut_input (ina) &
lut_input (inb) &
lut_input (inc) &
lut_input (ind)
) ;
END ;
Note: For information about
Quartus® Prime
primitive instantiation, go to Using a
Quartus® Prime Logic
Function.