/* 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" // 译码模块 // 纯组合逻辑电路 module id( input wire rst, // from if_id input wire[`InstBus] inst_i, // 指令内容 input wire[`InstAddrBus] inst_addr_i, // 指令地址 // from regs input wire[`RegBus] reg1_rdata_i, // 通用寄存器1输入数据 input wire[`RegBus] reg2_rdata_i, // 通用寄存器2输入数据 // from csr reg input wire[`RegBus] csr_rdata_i, // CSR寄存器输入数据 // from ex input wire ex_jump_flag_i, // 跳转标志 // to regs output reg[`RegAddrBus] reg1_raddr_o, // 读通用寄存器1地址 output reg[`RegAddrBus] reg2_raddr_o, // 读通用寄存器2地址 // to csr reg output reg[`MemAddrBus] csr_raddr_o, // 读CSR寄存器地址 output wire mem_req_o, // 向总线请求访问内存标志 // to ex output reg[`InstBus] inst_o, // 指令内容 output reg[`InstAddrBus] inst_addr_o, // 指令地址 output reg[`RegBus] reg1_rdata_o, // 通用寄存器1数据 output reg[`RegBus] reg2_rdata_o, // 通用寄存器2数据 output reg reg_we_o, // 写通用寄存器标志 output reg[`RegAddrBus] reg_waddr_o, // 写通用寄存器地址 output reg csr_we_o, // 写CSR寄存器标志 output reg[`RegBus] csr_rdata_o, // CSR寄存器数据 output reg[`MemAddrBus] csr_waddr_o // 写CSR寄存器地址 ); wire[6:0] opcode = inst_i[6:0]; wire[2:0] funct3 = inst_i[14:12]; wire[6:0] funct7 = inst_i[31:25]; wire[4:0] rd = inst_i[11:7]; wire[4:0] rs1 = inst_i[19:15]; wire[4:0] rs2 = inst_i[24:20]; reg mem_req; // 跳转时不向总线请求访问内存 assign mem_req_o = ((mem_req == `RIB_REQ) && (ex_jump_flag_i == `JumpDisable)); always @ (*) begin if (rst == `RstEnable) begin reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; csr_raddr_o = `ZeroWord; inst_o = `INST_NOP; inst_addr_o = `ZeroWord; reg1_rdata_o = `ZeroWord; reg2_rdata_o = `ZeroWord; csr_rdata_o = `ZeroWord; reg_we_o = `WriteDisable; csr_we_o = `WriteDisable; reg_waddr_o = `ZeroReg; csr_waddr_o = `ZeroWord; mem_req = `RIB_NREQ; end else begin inst_o = inst_i; inst_addr_o = inst_addr_i; reg1_rdata_o = reg1_rdata_i; reg2_rdata_o = reg2_rdata_i; csr_rdata_o = csr_rdata_i; mem_req = `RIB_NREQ; csr_raddr_o = `ZeroWord; csr_waddr_o = `ZeroWord; csr_we_o = `WriteDisable; case (opcode) `INST_TYPE_I: begin case (funct3) `INST_ADDI, `INST_SLTI, `INST_SLTIU, `INST_XORI, `INST_ORI, `INST_ANDI, `INST_SLLI, `INST_SRI: begin reg_we_o = `WriteEnable; reg_waddr_o = rd; reg1_raddr_o = rs1; reg2_raddr_o = `ZeroReg; end default: begin reg_we_o = `WriteDisable; reg_waddr_o = `ZeroReg; reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; end endcase end `INST_TYPE_R_M: begin if ((funct7 == 7'b0000000) || (funct7 == 7'b0100000)) begin case (funct3) `INST_ADD_SUB, `INST_SLL, `INST_SLT, `INST_SLTU, `INST_XOR, `INST_SR, `INST_OR, `INST_AND: begin reg_we_o = `WriteEnable; reg_waddr_o = rd; reg1_raddr_o = rs1; reg2_raddr_o = rs2; end default: begin reg_we_o = `WriteDisable; reg_waddr_o = `ZeroReg; reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; end endcase end else if (funct7 == 7'b0000001) begin case (funct3) `INST_MUL, `INST_MULHU, `INST_MULH, `INST_MULHSU: begin reg_we_o = `WriteEnable; reg_waddr_o = rd; reg1_raddr_o = rs1; reg2_raddr_o = rs2; end `INST_DIV, `INST_DIVU, `INST_REM, `INST_REMU: begin reg_we_o = `WriteDisable; reg_waddr_o = rd; reg1_raddr_o = rs1; reg2_raddr_o = rs2; end default: begin reg_we_o = `WriteDisable; reg_waddr_o = `ZeroReg; reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; end endcase end else begin reg_we_o = `WriteDisable; reg_waddr_o = `ZeroReg; reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; end end `INST_TYPE_L: begin case (funct3) `INST_LB, `INST_LH, `INST_LW, `INST_LBU, `INST_LHU: begin reg1_raddr_o = rs1; reg2_raddr_o = `ZeroReg; reg_we_o = `WriteEnable; reg_waddr_o = rd; mem_req = `RIB_REQ; end default: begin reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; reg_we_o = `WriteDisable; reg_waddr_o = `ZeroReg; end endcase end `INST_TYPE_S: begin case (funct3) `INST_SB, `INST_SW, `INST_SH: begin reg1_raddr_o = rs1; reg2_raddr_o = rs2; reg_we_o = `WriteDisable; reg_waddr_o = `ZeroReg; mem_req = `RIB_REQ; end default: begin reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; reg_we_o = `WriteDisable; reg_waddr_o = `ZeroReg; end endcase end `INST_TYPE_B: begin case (funct3) `INST_BEQ, `INST_BNE, `INST_BLT, `INST_BGE, `INST_BLTU, `INST_BGEU: begin reg1_raddr_o = rs1; reg2_raddr_o = rs2; reg_we_o = `WriteDisable; reg_waddr_o = `ZeroReg; end default: begin reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; reg_we_o = `WriteDisable; reg_waddr_o = `ZeroReg; end endcase end `INST_JAL: begin reg_we_o = `WriteEnable; reg_waddr_o = rd; reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; end `INST_JALR: begin reg_we_o = `WriteEnable; reg1_raddr_o = rs1; reg2_raddr_o = `ZeroReg; reg_waddr_o = rd; end `INST_LUI: begin reg_we_o = `WriteEnable; reg_waddr_o = rd; reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; end `INST_AUIPC: begin reg_we_o = `WriteEnable; reg_waddr_o = rd; reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; end `INST_NOP_OP: begin reg_we_o = `WriteDisable; reg_waddr_o = `ZeroReg; reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; end `INST_FENCE: begin reg_we_o = `WriteDisable; reg_waddr_o = `ZeroReg; reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; end `INST_CSR: begin reg_we_o = `WriteDisable; reg_waddr_o = `ZeroReg; reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; csr_raddr_o = {20'h0, inst_i[31:20]}; csr_waddr_o = {20'h0, inst_i[31:20]}; case (funct3) `INST_CSRRW, `INST_CSRRS, `INST_CSRRC: begin reg1_raddr_o = rs1; reg2_raddr_o = `ZeroReg; reg_we_o = `WriteEnable; reg_waddr_o = rd; csr_we_o = `WriteEnable; end `INST_CSRRWI, `INST_CSRRSI, `INST_CSRRCI: begin reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; reg_we_o = `WriteEnable; reg_waddr_o = rd; csr_we_o = `WriteEnable; end default: begin reg_we_o = `WriteDisable; reg_waddr_o = `ZeroReg; reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; csr_we_o = `WriteDisable; end endcase end default: begin reg_we_o = `WriteDisable; reg_waddr_o = `ZeroReg; reg1_raddr_o = `ZeroReg; reg2_raddr_o = `ZeroReg; end endcase end end endmodule