## MAX+PLUS II Architecture Control Logic Function Instantiation Example for VHDL

You can instantiate Altera®-provided logic functions from the alt_mf library, which includes the `a_8fadd`, `a_8mcomp`, `a_8count`, and `a_81mux` functions, in VHDL designs. Altera provides behavioral descriptions of these functions that support pre-synthesis/pre-route simulation of your top-level design with the VHDL System Simulator (VSS).

When you instantiate one of these functions, you can either include a Component Declaration for the function, or use the Altera-provided shell script analyze_vss to create a design library called altera so that you can reference the functions through the VHDL Library and Use Clauses. The Library and Use Clauses direct the Design Compiler or FPGA Compiler to incorporate the library files when it compiles your top-level design file. The analyze_vss shell script creates the altera design library when it analyzes the VSS simulation models in the /usr/maxplus2/synopsys/library/alt_mf/lib directory. See Setting up VSS Configuration Files for more information on using the analyze_vss shell script.

Figure 1 shows an example of an 8-bit counter that is instantiated using the `a_8count` function.

Figure 1. Sample VHDL File with Logic Function Instantiation

    LIBRARY ieee;
    USE ieee.std_logic_1164.ALL;
    LIBRARY altera;
    USE altera.maxplus2.ALL;
    ENTITY counter IS
    PORT (clock,ena,load,dnup,set,clear : IN STD_LOGIC;
       i    : IN STD_LOGIC_VECTOR (7 DOWNTO 0);
       q    : OUT STD_LOGIC_VECTOR(7 DOWNTO 0);
       cout : OUT STD_LOGIC);
    END counter;
    ARCHITECTURE structure OF counter IS
    BEGIN
       u1   : a_8count
       PORT MAP (a=>i(0), b=>i(1), c=>i(2), d=>i(3), e=>i(4),
                f=>i(5), g=>i(6), h=>i(7), ldn=>load, gn=>ena,
                dnup=>dnup, setn=>set, clrn=>clear, clk=>clock,
                qa=>q(0), qb=>q(1), qc=>q(2), qd=>q(3), qe=>q(4),
                qf=>q(5), qg=>q(6), qh=>q(7), cout=>cout);
    END structure;
    CONFIGURATION conf OF counter IS
       FOR structure
       END FOR;
    END conf;

Last Updated: August 28, 2000 for MAX+PLUS II version 10.0 |
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