apb_decoder.v

// APB Decoder Module
// Decodes address and generates PSEL for each slave

module apb_decoder #(
    parameter ADDR_WIDTH = 32,
    parameter NUM_SLAVES = 4
)(
    input wire [ADDR_WIDTH-1:0] PADDR,
    input wire PSEL,  // Master PSEL
    output reg [NUM_SLAVES-1:0] slave_sel  // One-hot slave select
);

    // Address ranges for each slave (can be parameterized)
    // Slave 0: 0x0000_0000 - 0x0000_0FFF
    // Slave 1: 0x0000_1000 - 0x0000_1FFF
    // Slave 2: 0x0000_2000 - 0x0000_2FFF
    // Slave 3: 0x0000_3000 - 0x0000_3FFF
    
    always @(*) begin
        slave_sel = 0;
        if (PSEL) begin
            case (PADDR[15:12])
                4'h0: slave_sel[0] = 1'b1;
                4'h1: slave_sel[1] = 1'b1;
                4'h2: slave_sel[2] = 1'b1;
                4'h3: slave_sel[3] = 1'b1;
                default: slave_sel = 0; // No slave selected
            endcase
        end
    end

endmodule