AHDL: Parameterized Multiplexer (lpm_mux)
In this example, four 4-bit-wide buses (a, b, c, and d) are multiplexed.
The widths of the four buses are specified with the parameter
LPM_WIDTH, the number of buses being multiplexed is specified with
LPM_SIZE, and the number of select lines is specified with
LPM_WIDTHS. You can change any of these parameters to suit the needs
of your design. The ports of the LPM function are defined in a
Function Prototype Statement (shown in blue text). An Instance Declaration (shown in red text) implements an instance of
the function.
For more information on using this example in your project, go to:
mux.tdf
FUNCTION lpm_mux (data[LPM_SIZE-1..0][LPM_WIDTH-1..0],
sel[LPM_WIDTHS-1..0])
WITH (LPM_WIDTH, LPM_SIZE, LPM_WIDTHS, CASCADE_CHAIN)
RETURNS (result[LPM_WIDTH-1..0]);
SUBDESIGN mux
(
a[3..0], b[3..0], c[3..0], d[3..0] : INPUT;
select[1..0] : INPUT;
result[3..0] : OUTPUT;
)
BEGIN
result[3..0] = lpm_mux (a[3..0], b[3..0], c[3..0], d[3..0],
select[1..0])
WITH (LPM_WIDTH=4, LPM_SIZE=4, LPM_WIDTHS=2);
END;
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