//+FHDR--------------------------------------------------------------------------------------------------------
//  Company: 
//-----------------------------------------------------------------------------------------------------------------
//  File Name             :    qbmcu_exu_bjp.v
//  Department            :    
//  Author                :    PWY
//  Author's Tel          :     
//-----------------------------------------------------------------------------------------------------------------
//  Relese History
//  Version     Date            Author          Description
//  0.1         2024-03-13      PWY            This module to implement the Conditional Branch Instructions,
//                                             which is mostly share the datapath with ALU adder to resolve the comparasion
//                                             result to save gatecount to mininum
//-----------------------------------------------------------------------------------------------------------------
//  Keywords            :       
//
//-----------------------------------------------------------------------------------------------------------------
//  Parameter
//
//-----------------------------------------------------------------------------------------------------------------
//  Purpose                 :
//                      
//-----------------------------------------------------------------------------------------------------------------
//  Target Device:        
//  Tool versions:        
//-----------------------------------------------------------------------------------------------------------------
//  Reuse Issues
//  Reset Strategy: 
//  Clock Domains: 
//  Critical Timing:
//  Asynchronous I/F:
//  Synthesizable (y/n): 
//  Other:
//-FHDR--------------------------------------------------------------------------------------------------------
                                                                         

`include "qbmcu_defines.v"
                                                                         

module qbmcu_exu_bjp(
  //system port
   input                                 clk
  ,input                                 rst_n
  //////////////////////////////////////////////////////////////
  //////////////////////////////////////////////////////////////
  // The Handshake Interface
  //
  ,input  [`QBMCU_XLEN-1             :0] bjp_i_rs1
  ,input  [`QBMCU_XLEN-1             :0] bjp_i_rs2
  ,input  [`QBMCU_XLEN-1             :0] bjp_i_imm
  ,input  [`QBMCU_PC_SIZE-1          :0] bjp_i_pc
  ,input  [`QBMCU_DECINFO_BJP_WIDTH-1:0] bjp_i_info
  ,input                                 bjp_i_op
  //The enable signal from the master control state machine
  ,input                                 bjp_i_active
  
  //////////////////////////////////////////////////////////////
  //Data sent to the write-back module
  //write back interface
  ,output [`QBMCU_XLEN-1             :0] bjp_o_wbck_wdat
  ,output                                bjp_o_wbck_valid
  //////////////////////////////////////////////////////////////
  //update the value of the program counter (PC)
  ,output                               update_pc_req
  ,output [`QBMCU_PC_SIZE-1         :0] update_pc_value 
  //////////////////////////////////////////////////////////////
  // To share the ALU datapath
  // The operands and info to ALU
  ,output [`QBMCU_XLEN-1             :0] bjp_req_alu_op1
  ,output [`QBMCU_XLEN-1             :0] bjp_req_alu_op2
  ,output                                bjp_req_alu_cmp_eq 
  ,output                                bjp_req_alu_cmp_ne 
  ,output                                bjp_req_alu_cmp_lt 
  ,output                                bjp_req_alu_cmp_gt 
  ,output                                bjp_req_alu_cmp_ltu
  ,output                                bjp_req_alu_cmp_gtu
  ,output                                bjp_req_alu_add
                                     
  ,input                                 bjp_req_alu_cmp_res
  ,input  [`QBMCU_XLEN-1             :0] bjp_req_alu_add_res
  );


wire bxx   = bjp_i_op & bjp_i_info [`QBMCU_DECINFO_BJP_BXX ]; 
wire jump  = bjp_i_op & bjp_i_info [`QBMCU_DECINFO_BJP_JUMP ]; 
wire jalr  = bjp_i_op & bjp_i_info [`QBMCU_DECINFO_BJP_JALR ]; 

wire wbck_link = jump;

assign bjp_req_alu_op1 = wbck_link ? 
                          bjp_i_pc 
                        : bjp_i_rs1;
assign bjp_req_alu_op2 = wbck_link ? 
                         `QBMCU_XLEN'd4
                        : bjp_i_rs2;

wire   cmt_bjp = bxx | jump;


assign bjp_req_alu_cmp_eq  = bjp_i_op & bjp_i_info [`QBMCU_DECINFO_BJP_BEQ  ]; 
assign bjp_req_alu_cmp_ne  = bjp_i_op & bjp_i_info [`QBMCU_DECINFO_BJP_BNE  ]; 
assign bjp_req_alu_cmp_lt  = bjp_i_op & bjp_i_info [`QBMCU_DECINFO_BJP_BLT  ]; 
assign bjp_req_alu_cmp_gt  = bjp_i_op & bjp_i_info [`QBMCU_DECINFO_BJP_BGT  ]; 
assign bjp_req_alu_cmp_ltu = bjp_i_op & bjp_i_info [`QBMCU_DECINFO_BJP_BLTU ]; 
assign bjp_req_alu_cmp_gtu = bjp_i_op & bjp_i_info [`QBMCU_DECINFO_BJP_BGTU ]; 

assign bjp_req_alu_add  = wbck_link;

wire   cmt_rslv  = jump ? 1'b1 : bjp_req_alu_cmp_res;


//bjp_o_wbck_wdat
sirv_gnrl_dfflr #(`QBMCU_XLEN) bjp_o_wbck_wdat_dfflr (bjp_i_active, bjp_req_alu_add_res,  bjp_o_wbck_wdat, clk, rst_n);
//bjp_o_wbck_valid
sirv_gnrl_dfflr #(1) bjp_o_wbck_valid_dfflr (bjp_i_active, bjp_i_op,  bjp_o_wbck_valid, clk, rst_n);

wire [`QBMCU_PC_SIZE-1:0] pc_temp = jalr ? bjp_i_rs1 : bjp_i_pc;

wire [`QBMCU_PC_SIZE-1:0] update_pc_value_w = (pc_temp + bjp_i_imm[`QBMCU_PC_SIZE-1:0]);
wire                      update_pc_req_w   = cmt_bjp & cmt_rslv;

//wire bjp_i_active_r;
//sirv_gnrl_dffr #(1)bjp_i_active_r_dffr (bjp_i_active, bjp_i_active_r, clk, rst_n);

//update_pc_vaule
//sirv_gnrl_dfflr #(`QBMCU_PC_SIZE) update_pc_vaule_dfflr (bjp_i_active_r, update_pc_value_w,  update_pc_value, clk, rst_n);
//update_pc_req
//sirv_gnrl_dfflr #(1) update_pc_req_dfflr (bjp_i_active_r, update_pc_req_w,  update_pc_req, clk, rst_n);

assign update_pc_value = update_pc_value_w;
assign update_pc_req   = update_pc_req_w;
endmodule

`include "qbmcu_undefines.v"