Subversion Repositories pentevo

// (c) NedoPC 2010
//
// wait generator for Z80

`include "../include/tune.v"


module zwait(

        input  wire rst_n,

        input  wire wait_start_gluclock,
        input  wire wait_start_comport,

        input  wire wait_end,


        output reg  [6:0] waits,

        output wire wait_n,
        output wire spiint_n
);


`ifdef SIMULATE
        initial
        begin
                force waits = 7'd0;
        end
`endif


        wire wait_off_n;
        assign wait_off_n = (~wait_end) & rst_n;

        // RS-flipflops
        //
        always @(posedge wait_start_gluclock, negedge wait_off_n)
        if( !wait_off_n )
                waits[0] <= 1'b0;
        else if( wait_start_gluclock )
                waits[0] <= 1'b1;
        //
        always @(posedge wait_start_comport, negedge wait_off_n)
        if( !wait_off_n )
                waits[1] <= 1'b0;
        else if( wait_start_comport )
                waits[1] <= 1'b1;


        always @(posedge wait_end) // just dummy for future extensions
        begin
                waits[6:2] <= 6'd0;
        end



        assign spiint_n = ~|waits;
        assign wait_n = spiint_n ? 1'bZ : 1'b0;

endmodule