/*                                                                      
 Copyright 2020 Blue Liang, liangkangnan@163.com
                                                                         
 Licensed under the Apache License, Version 2.0 (the "License");         
 you may not use this file except in compliance with the License.        
 You may obtain a copy of the License at                                 
                                                                         
     http://www.apache.org/licenses/LICENSE-2.0                          
                                                                         
 Unless required by applicable law or agreed to in writing, software    
 distributed under the License is distributed on an "AS IS" BASIS,       
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and     
 limitations under the License.                                          
 */

// 带默认值和控制信号的流水线触发器
module gen_pipe_dff #(
    parameter DW = 32)(

    input wire clk,
    input wire rst,
    input wire hold_en,

    input wire[DW-1:0] def_val,
    input wire[DW-1:0] din,
    output wire[DW-1:0] qout

    );

    reg[DW-1:0] qout_r;

    always @ (posedge clk) begin
        if (!rst | hold_en) begin
            qout_r <= def_val;
        end else begin
            qout_r <= din;
        end
    end

    assign qout = qout_r;

endmodule

// 复位后输出为0的触发器
module gen_rst_0_dff #(
    parameter DW = 32)(

    input wire clk,
    input wire rst,

    input wire[DW-1:0] din,
    output wire[DW-1:0] qout

    );

    reg[DW-1:0] qout_r;

    always @ (posedge clk) begin
        if (!rst) begin
            qout_r <= {DW{1'b0}};
        end else begin                  
            qout_r <= din;
        end
    end

    assign qout = qout_r;

endmodule

// 复位后输出为1的触发器
module gen_rst_1_dff #(
    parameter DW = 32)(

    input wire clk,
    input wire rst,

    input wire[DW-1:0] din,
    output wire[DW-1:0] qout

    );

    reg[DW-1:0] qout_r;

    always @ (posedge clk) begin
        if (!rst) begin
            qout_r <= {DW{1'b1}};
        end else begin                  
            qout_r <= din;
        end
    end

    assign qout = qout_r;

endmodule

// 复位后输出为默认值的触发器
module gen_rst_def_dff #(
    parameter DW = 32)(

    input wire clk,
    input wire rst,
    input wire[DW-1:0] def_val,

    input wire[DW-1:0] din,
    output wire[DW-1:0] qout

    );

    reg[DW-1:0] qout_r;

    always @ (posedge clk) begin
        if (!rst) begin
            qout_r <= def_val;
        end else begin                  
            qout_r <= din;
        end
    end

    assign qout = qout_r;

endmodule

// 带使能端、复位后输出为0的触发器
module gen_en_dff #(
    parameter DW = 32)(

    input wire clk,
    input wire rst,

    input wire en,
    input wire[DW-1:0] din,
    output wire[DW-1:0] qout

    );

    reg[DW-1:0] qout_r;

    always @ (posedge clk) begin
        if (!rst) begin
            qout_r <= {DW{1'b0}};
        end else if (en == 1'b1) begin
            qout_r <= din;
        end
    end

    assign qout = qout_r;

endmodule