/*                                                                      
 Copyright 2019 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.                                          
 */

`include "defines.v"

// 通用寄存器模块
module gpr_reg(

    input wire clk,
    input wire rst_n,

    input wire we_i,                        // 写寄存器使能
    input wire[4:0] waddr_i,                // 写寄存器地址
    input wire[31:0] wdata_i,               // 写寄存器数据

    input wire[4:0] raddr1_i,               // 读寄存器1地址
    output wire[31:0] rdata1_o,             // 读寄存器1数据

    input wire[4:0] raddr2_i,               // 读寄存器2地址
    output wire[31:0] rdata2_o              // 读寄存器2数据

    );

    wire[32-1:0] regs[32-1:0];
    wire[32-1:0] we;

    genvar i;

    generate
        for (i = 0; i < 32; i = i + 1) begin
            // x0 cannot be wrote since it is constant-zeros
            if (i == 0) begin
                assign we[i] = 1'b0;
                assign regs[i] = 32'h0;
            end else begin
                assign we[i] = we_i & (waddr_i == i);
                gen_en_dffnr #(32) rf_dff(clk, we[i], wdata_i, regs[i]);
            end
        end
    endgenerate

    assign rdata1_o = regs[raddr1_i];
    assign rdata2_o = regs[raddr2_i];

    // for debug
    wire[31:0] ra = regs[1];
    wire[31:0] sp = regs[2];
    wire[31:0] gp = regs[3];
    wire[31:0] tp = regs[4];
    wire[31:0] t0 = regs[5];
    wire[31:0] t1 = regs[6];
    wire[31:0] t2 = regs[7];
    wire[31:0] s0 = regs[8];
    wire[31:0] fp = regs[8];
    wire[31:0] s1 = regs[9];
    wire[31:0] a0 = regs[10];
    wire[31:0] a1 = regs[11];
    wire[31:0] a2 = regs[12];
    wire[31:0] a3 = regs[13];
    wire[31:0] a4 = regs[14];
    wire[31:0] a5 = regs[15];
    wire[31:0] a6 = regs[16];
    wire[31:0] a7 = regs[17];
    wire[31:0] s2 = regs[18];
    wire[31:0] s3 = regs[19];
    wire[31:0] s4 = regs[20];
    wire[31:0] s5 = regs[21];
    wire[31:0] s6 = regs[22];
    wire[31:0] s7 = regs[23];
    wire[31:0] s8 = regs[24];
    wire[31:0] s9 = regs[25];
    wire[31:0] s10 = regs[26];
    wire[31:0] s11 = regs[27];
    wire[31:0] t3 = regs[28];
    wire[31:0] t4 = regs[29];
    wire[31:0] t5 = regs[30];
    wire[31:0] t6 = regs[31];

endmodule