| // Copyright lowRISC contributors. |
| // Copyright 2017 ETH Zurich and University of Bologna. |
| // Licensed under the Apache License, Version 2.0, see LICENSE for details. |
| // SPDX-License-Identifier: Apache-2.0 |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| // Engineer: Matthias Baer - baermatt@student.ethz.ch // |
| // // |
| // Additional contributions by: // |
| // Sven Stucki - svstucki@student.ethz.ch // |
| // // |
| // // |
| // Design Name: RISC-V processor core // |
| // Project Name: ibex // |
| // Language: SystemVerilog // |
| // // |
| // Description: Defines for various constants used by the processor core. // |
| // // |
| //////////////////////////////////////////////////////////////////////////////// |
| |
| module ibex_decoder ( |
| deassert_we_i, |
| data_misaligned_i, |
| branch_mux_i, |
| jump_mux_i, |
| illegal_insn_o, |
| ebrk_insn_o, |
| mret_insn_o, |
| dret_insn_o, |
| ecall_insn_o, |
| pipe_flush_o, |
| instr_rdata_i, |
| illegal_c_insn_i, |
| alu_operator_o, |
| alu_op_a_mux_sel_o, |
| alu_op_b_mux_sel_o, |
| imm_a_mux_sel_o, |
| imm_b_mux_sel_o, |
| mult_int_en_o, |
| div_int_en_o, |
| multdiv_operator_o, |
| multdiv_signed_mode_o, |
| regfile_we_o, |
| csr_access_o, |
| csr_op_o, |
| csr_status_o, |
| data_req_o, |
| data_we_o, |
| data_type_o, |
| data_sign_extension_o, |
| data_reg_offset_o, |
| jump_in_id_o, |
| branch_in_id_o, |
| eFPGA_operator_o, |
| eFPGA_int_en_o, |
| eFPGA_delay_o |
| ); |
| parameter [0:0] RV32M = 1; |
| input wire deassert_we_i; |
| input wire data_misaligned_i; |
| input wire branch_mux_i; |
| input wire jump_mux_i; |
| output reg illegal_insn_o; |
| output reg ebrk_insn_o; |
| output reg mret_insn_o; |
| output reg dret_insn_o; |
| output reg ecall_insn_o; |
| output reg pipe_flush_o; |
| input wire [31:0] instr_rdata_i; |
| input wire illegal_c_insn_i; |
| output reg [4:0] alu_operator_o; |
| output reg [1:0] alu_op_a_mux_sel_o; |
| output reg alu_op_b_mux_sel_o; |
| output reg imm_a_mux_sel_o; |
| output reg [2:0] imm_b_mux_sel_o; |
| output wire mult_int_en_o; |
| output wire div_int_en_o; |
| output reg [1:0] multdiv_operator_o; |
| output reg [1:0] multdiv_signed_mode_o; |
| output wire regfile_we_o; |
| output reg csr_access_o; |
| output wire [1:0] csr_op_o; |
| output reg csr_status_o; |
| output wire data_req_o; |
| output reg data_we_o; |
| output reg [1:0] data_type_o; |
| output reg data_sign_extension_o; |
| output reg [1:0] data_reg_offset_o; |
| output wire jump_in_id_o; |
| output wire branch_in_id_o; |
| output reg [1:0] eFPGA_operator_o; |
| output wire eFPGA_int_en_o; |
| output reg [3:0] eFPGA_delay_o; |
| reg regfile_we; |
| reg data_req; |
| reg mult_int_en; |
| reg div_int_en; |
| reg branch_in_id; |
| reg jump_in_id; |
| reg eFPGA_int_en; |
| reg [1:0] csr_op; |
| reg csr_illegal; |
| reg [6:0] opcode; |
| localparam [4:0] ibex_defines_ALU_ADD = 0; |
| localparam [4:0] ibex_defines_ALU_AND = 4; |
| localparam [4:0] ibex_defines_ALU_EQ = 16; |
| localparam [4:0] ibex_defines_ALU_GE = 14; |
| localparam [4:0] ibex_defines_ALU_GEU = 15; |
| localparam [4:0] ibex_defines_ALU_LT = 8; |
| localparam [4:0] ibex_defines_ALU_LTU = 9; |
| localparam [4:0] ibex_defines_ALU_NE = 17; |
| localparam [4:0] ibex_defines_ALU_OR = 3; |
| localparam [4:0] ibex_defines_ALU_SLL = 7; |
| localparam [4:0] ibex_defines_ALU_SLT = 18; |
| localparam [4:0] ibex_defines_ALU_SLTU = 19; |
| localparam [4:0] ibex_defines_ALU_SRA = 5; |
| localparam [4:0] ibex_defines_ALU_SRL = 6; |
| localparam [4:0] ibex_defines_ALU_SUB = 1; |
| localparam [4:0] ibex_defines_ALU_XOR = 2; |
| localparam [11:0] ibex_defines_CSR_DCSR = 12'h7b0; |
| localparam [11:0] ibex_defines_CSR_DPC = 12'h7b1; |
| localparam [11:0] ibex_defines_CSR_DSCRATCH0 = 12'h7b2; |
| localparam [11:0] ibex_defines_CSR_DSCRATCH1 = 12'h7b3; |
| localparam [11:0] ibex_defines_CSR_MSTATUS = 12'h300; |
| localparam [1:0] ibex_defines_CSR_OP_CLEAR = 3; |
| localparam [1:0] ibex_defines_CSR_OP_NONE = 0; |
| localparam [1:0] ibex_defines_CSR_OP_SET = 2; |
| localparam [1:0] ibex_defines_CSR_OP_WRITE = 1; |
| localparam [0:0] ibex_defines_IMM_A_Z = 0; |
| localparam [0:0] ibex_defines_IMM_A_ZERO = 1; |
| localparam [2:0] ibex_defines_IMM_B_B = 2; |
| localparam [2:0] ibex_defines_IMM_B_I = 0; |
| localparam [2:0] ibex_defines_IMM_B_J = 4; |
| localparam [2:0] ibex_defines_IMM_B_PCINCR = 5; |
| localparam [2:0] ibex_defines_IMM_B_S = 1; |
| localparam [2:0] ibex_defines_IMM_B_U = 3; |
| localparam [1:0] ibex_defines_MD_OP_DIV = 2; |
| localparam [1:0] ibex_defines_MD_OP_MULH = 1; |
| localparam [1:0] ibex_defines_MD_OP_MULL = 0; |
| localparam [1:0] ibex_defines_MD_OP_REM = 3; |
| localparam [6:0] ibex_defines_OPCODE_AUIPC = 7'h17; |
| localparam [6:0] ibex_defines_OPCODE_BRANCH = 7'h63; |
| localparam [6:0] ibex_defines_OPCODE_FENCE = 7'h0f; |
| localparam [6:0] ibex_defines_OPCODE_JAL = 7'h6f; |
| localparam [6:0] ibex_defines_OPCODE_JALR = 7'h67; |
| localparam [6:0] ibex_defines_OPCODE_LOAD = 7'h03; |
| localparam [6:0] ibex_defines_OPCODE_LUI = 7'h37; |
| localparam [6:0] ibex_defines_OPCODE_OP = 7'h33; |
| localparam [6:0] ibex_defines_OPCODE_OPIMM = 7'h13; |
| localparam [6:0] ibex_defines_OPCODE_STORE = 7'h23; |
| localparam [6:0] ibex_defines_OPCODE_SYSTEM = 7'h73; |
| localparam [6:0] ibex_defines_OPCODE_eFPGA = 7'h0b; |
| localparam [1:0] ibex_defines_OP_A_CURRPC = 1; |
| localparam [1:0] ibex_defines_OP_A_IMM = 2; |
| localparam [1:0] ibex_defines_OP_A_REGA_OR_FWD = 0; |
| localparam [0:0] ibex_defines_OP_B_IMM = 1; |
| localparam [0:0] ibex_defines_OP_B_REGB_OR_FWD = 0; |
| always @(*) begin |
| jump_in_id = 1'b0; |
| branch_in_id = 1'b0; |
| alu_operator_o = ibex_defines_ALU_SLTU; |
| alu_op_a_mux_sel_o = ibex_defines_OP_A_REGA_OR_FWD; |
| alu_op_b_mux_sel_o = ibex_defines_OP_B_REGB_OR_FWD; |
| imm_a_mux_sel_o = ibex_defines_IMM_A_ZERO; |
| imm_b_mux_sel_o = ibex_defines_IMM_B_I; |
| mult_int_en = 1'b0; |
| div_int_en = 1'b0; |
| multdiv_operator_o = ibex_defines_MD_OP_MULL; |
| multdiv_signed_mode_o = 2'b00; |
| eFPGA_int_en = 1'b0; |
| eFPGA_operator_o = 2'b00; |
| regfile_we = 1'b0; |
| csr_access_o = 1'b0; |
| csr_status_o = 1'b0; |
| csr_illegal = 1'b0; |
| csr_op = ibex_defines_CSR_OP_NONE; |
| data_we_o = 1'b0; |
| data_type_o = 2'b00; |
| data_sign_extension_o = 1'b0; |
| data_reg_offset_o = 2'b00; |
| data_req = 1'b0; |
| illegal_insn_o = 1'b0; |
| ebrk_insn_o = 1'b0; |
| mret_insn_o = 1'b0; |
| dret_insn_o = 1'b0; |
| ecall_insn_o = 1'b0; |
| pipe_flush_o = 1'b0; |
| opcode = instr_rdata_i[6:0]; |
| case (opcode) |
| ibex_defines_OPCODE_JAL: begin |
| jump_in_id = 1'b1; |
| if (jump_mux_i) begin |
| alu_op_a_mux_sel_o = ibex_defines_OP_A_CURRPC; |
| alu_op_b_mux_sel_o = ibex_defines_OP_B_IMM; |
| imm_b_mux_sel_o = ibex_defines_IMM_B_J; |
| alu_operator_o = ibex_defines_ALU_ADD; |
| regfile_we = 1'b0; |
| end |
| else begin |
| alu_op_a_mux_sel_o = ibex_defines_OP_A_CURRPC; |
| alu_op_b_mux_sel_o = ibex_defines_OP_B_IMM; |
| imm_b_mux_sel_o = ibex_defines_IMM_B_PCINCR; |
| alu_operator_o = ibex_defines_ALU_ADD; |
| regfile_we = 1'b1; |
| end |
| end |
| ibex_defines_OPCODE_JALR: begin |
| jump_in_id = 1'b1; |
| if (jump_mux_i) begin |
| alu_op_a_mux_sel_o = ibex_defines_OP_A_REGA_OR_FWD; |
| alu_op_b_mux_sel_o = ibex_defines_OP_B_IMM; |
| imm_b_mux_sel_o = ibex_defines_IMM_B_I; |
| alu_operator_o = ibex_defines_ALU_ADD; |
| regfile_we = 1'b0; |
| end |
| else begin |
| alu_op_a_mux_sel_o = ibex_defines_OP_A_CURRPC; |
| alu_op_b_mux_sel_o = ibex_defines_OP_B_IMM; |
| imm_b_mux_sel_o = ibex_defines_IMM_B_PCINCR; |
| alu_operator_o = ibex_defines_ALU_ADD; |
| regfile_we = 1'b1; |
| end |
| if (instr_rdata_i[14:12] != 3'b000) begin |
| jump_in_id = 1'b0; |
| regfile_we = 1'b0; |
| illegal_insn_o = 1'b1; |
| end |
| end |
| ibex_defines_OPCODE_BRANCH: begin |
| branch_in_id = 1'b1; |
| if (branch_mux_i) |
| case (instr_rdata_i[14:12]) |
| 3'b000: alu_operator_o = ibex_defines_ALU_EQ; |
| 3'b001: alu_operator_o = ibex_defines_ALU_NE; |
| 3'b100: alu_operator_o = ibex_defines_ALU_LT; |
| 3'b101: alu_operator_o = ibex_defines_ALU_GE; |
| 3'b110: alu_operator_o = ibex_defines_ALU_LTU; |
| 3'b111: alu_operator_o = ibex_defines_ALU_GEU; |
| default: illegal_insn_o = 1'b1; |
| endcase |
| else begin |
| alu_op_a_mux_sel_o = ibex_defines_OP_A_CURRPC; |
| alu_op_b_mux_sel_o = ibex_defines_OP_B_IMM; |
| imm_b_mux_sel_o = ibex_defines_IMM_B_B; |
| alu_operator_o = ibex_defines_ALU_ADD; |
| regfile_we = 1'b0; |
| end |
| end |
| ibex_defines_OPCODE_STORE: begin |
| data_req = 1'b1; |
| data_we_o = 1'b1; |
| alu_operator_o = ibex_defines_ALU_ADD; |
| if (!instr_rdata_i[14]) begin |
| imm_b_mux_sel_o = ibex_defines_IMM_B_S; |
| alu_op_b_mux_sel_o = ibex_defines_OP_B_IMM; |
| end |
| else begin |
| data_req = 1'b0; |
| data_we_o = 1'b0; |
| illegal_insn_o = 1'b1; |
| end |
| case (instr_rdata_i[13:12]) |
| 2'b00: data_type_o = 2'b10; |
| 2'b01: data_type_o = 2'b01; |
| 2'b10: data_type_o = 2'b00; |
| default: begin |
| data_req = 1'b0; |
| data_we_o = 1'b0; |
| illegal_insn_o = 1'b1; |
| end |
| endcase |
| end |
| ibex_defines_OPCODE_LOAD: begin |
| data_req = 1'b1; |
| regfile_we = 1'b1; |
| data_type_o = 2'b00; |
| alu_operator_o = ibex_defines_ALU_ADD; |
| alu_op_b_mux_sel_o = ibex_defines_OP_B_IMM; |
| imm_b_mux_sel_o = ibex_defines_IMM_B_I; |
| data_sign_extension_o = ~instr_rdata_i[14]; |
| case (instr_rdata_i[13:12]) |
| 2'b00: data_type_o = 2'b10; |
| 2'b01: data_type_o = 2'b01; |
| 2'b10: data_type_o = 2'b00; |
| default: data_type_o = 2'b00; |
| endcase |
| if (instr_rdata_i[14:12] == 3'b111) begin |
| alu_op_b_mux_sel_o = ibex_defines_OP_B_REGB_OR_FWD; |
| data_sign_extension_o = ~instr_rdata_i[30]; |
| case (instr_rdata_i[31:25]) |
| 7'b0000000, 7'b0100000: data_type_o = 2'b10; |
| 7'b0001000, 7'b0101000: data_type_o = 2'b01; |
| 7'b0010000: data_type_o = 2'b00; |
| default: illegal_insn_o = 1'b1; |
| endcase |
| end |
| if (instr_rdata_i[14:12] == 3'b011) |
| illegal_insn_o = 1'b1; |
| end |
| ibex_defines_OPCODE_LUI: begin |
| alu_op_a_mux_sel_o = ibex_defines_OP_A_IMM; |
| alu_op_b_mux_sel_o = ibex_defines_OP_B_IMM; |
| imm_a_mux_sel_o = ibex_defines_IMM_A_ZERO; |
| imm_b_mux_sel_o = ibex_defines_IMM_B_U; |
| alu_operator_o = ibex_defines_ALU_ADD; |
| regfile_we = 1'b1; |
| end |
| ibex_defines_OPCODE_AUIPC: begin |
| alu_op_a_mux_sel_o = ibex_defines_OP_A_CURRPC; |
| alu_op_b_mux_sel_o = ibex_defines_OP_B_IMM; |
| imm_b_mux_sel_o = ibex_defines_IMM_B_U; |
| alu_operator_o = ibex_defines_ALU_ADD; |
| regfile_we = 1'b1; |
| end |
| ibex_defines_OPCODE_OPIMM: begin |
| alu_op_b_mux_sel_o = ibex_defines_OP_B_IMM; |
| imm_b_mux_sel_o = ibex_defines_IMM_B_I; |
| regfile_we = 1'b1; |
| case (instr_rdata_i[14:12]) |
| 3'b000: alu_operator_o = ibex_defines_ALU_ADD; |
| 3'b010: alu_operator_o = ibex_defines_ALU_SLT; |
| 3'b011: alu_operator_o = ibex_defines_ALU_SLTU; |
| 3'b100: alu_operator_o = ibex_defines_ALU_XOR; |
| 3'b110: alu_operator_o = ibex_defines_ALU_OR; |
| 3'b111: alu_operator_o = ibex_defines_ALU_AND; |
| 3'b001: begin |
| alu_operator_o = ibex_defines_ALU_SLL; |
| if (instr_rdata_i[31:25] != 7'b0000000) |
| illegal_insn_o = 1'b1; |
| end |
| 3'b101: |
| if (instr_rdata_i[31:25] == 7'b0000000) |
| alu_operator_o = ibex_defines_ALU_SRL; |
| else if (instr_rdata_i[31:25] == 7'b0100000) |
| alu_operator_o = ibex_defines_ALU_SRA; |
| else |
| illegal_insn_o = 1'b1; |
| default: |
| ; |
| endcase |
| end |
| ibex_defines_OPCODE_OP: begin |
| regfile_we = 1'b1; |
| if (instr_rdata_i[31]) |
| illegal_insn_o = 1'b1; |
| else if (!instr_rdata_i[28]) |
| case ({instr_rdata_i[30:25], instr_rdata_i[14:12]}) |
| 9'b000000000: alu_operator_o = ibex_defines_ALU_ADD; |
| 9'b100000000: alu_operator_o = ibex_defines_ALU_SUB; |
| 9'b000000010: alu_operator_o = ibex_defines_ALU_SLT; |
| 9'b000000011: alu_operator_o = ibex_defines_ALU_SLTU; |
| 9'b000000100: alu_operator_o = ibex_defines_ALU_XOR; |
| 9'b000000110: alu_operator_o = ibex_defines_ALU_OR; |
| 9'b000000111: alu_operator_o = ibex_defines_ALU_AND; |
| 9'b000000001: alu_operator_o = ibex_defines_ALU_SLL; |
| 9'b000000101: alu_operator_o = ibex_defines_ALU_SRL; |
| 9'b100000101: alu_operator_o = ibex_defines_ALU_SRA; |
| 9'b000001000: begin |
| alu_operator_o = ibex_defines_ALU_ADD; |
| multdiv_operator_o = ibex_defines_MD_OP_MULL; |
| mult_int_en = 1'b1; |
| multdiv_signed_mode_o = 2'b00; |
| illegal_insn_o = (RV32M ? 1'b0 : 1'b1); |
| end |
| 9'b000001001: begin |
| alu_operator_o = ibex_defines_ALU_ADD; |
| multdiv_operator_o = ibex_defines_MD_OP_MULH; |
| mult_int_en = 1'b1; |
| multdiv_signed_mode_o = 2'b11; |
| illegal_insn_o = (RV32M ? 1'b0 : 1'b1); |
| end |
| 9'b000001010: begin |
| alu_operator_o = ibex_defines_ALU_ADD; |
| multdiv_operator_o = ibex_defines_MD_OP_MULH; |
| mult_int_en = 1'b1; |
| multdiv_signed_mode_o = 2'b01; |
| illegal_insn_o = (RV32M ? 1'b0 : 1'b1); |
| end |
| 9'b000001011: begin |
| alu_operator_o = ibex_defines_ALU_ADD; |
| multdiv_operator_o = ibex_defines_MD_OP_MULH; |
| mult_int_en = 1'b1; |
| multdiv_signed_mode_o = 2'b00; |
| illegal_insn_o = (RV32M ? 1'b0 : 1'b1); |
| end |
| 9'b000001100: begin |
| alu_operator_o = ibex_defines_ALU_ADD; |
| multdiv_operator_o = ibex_defines_MD_OP_DIV; |
| div_int_en = 1'b1; |
| multdiv_signed_mode_o = 2'b11; |
| illegal_insn_o = (RV32M ? 1'b0 : 1'b1); |
| end |
| 9'b000001101: begin |
| alu_operator_o = ibex_defines_ALU_ADD; |
| multdiv_operator_o = ibex_defines_MD_OP_DIV; |
| div_int_en = 1'b1; |
| multdiv_signed_mode_o = 2'b00; |
| illegal_insn_o = (RV32M ? 1'b0 : 1'b1); |
| end |
| 9'b000001110: begin |
| alu_operator_o = ibex_defines_ALU_ADD; |
| multdiv_operator_o = ibex_defines_MD_OP_REM; |
| div_int_en = 1'b1; |
| multdiv_signed_mode_o = 2'b11; |
| illegal_insn_o = (RV32M ? 1'b0 : 1'b1); |
| end |
| 9'b000001111: begin |
| alu_operator_o = ibex_defines_ALU_ADD; |
| multdiv_operator_o = ibex_defines_MD_OP_REM; |
| div_int_en = 1'b1; |
| multdiv_signed_mode_o = 2'b00; |
| illegal_insn_o = (RV32M ? 1'b0 : 1'b1); |
| end |
| default: illegal_insn_o = 1'b1; |
| endcase |
| end |
| ibex_defines_OPCODE_eFPGA: begin |
| regfile_we = 1'b1; |
| eFPGA_operator_o = instr_rdata_i[13:12]; |
| eFPGA_delay_o = instr_rdata_i[28:25]; |
| eFPGA_int_en = 1'b1; |
| end |
| ibex_defines_OPCODE_FENCE: |
| if (instr_rdata_i[14:12] == 3'b000) begin |
| alu_operator_o = ibex_defines_ALU_ADD; |
| regfile_we = 1'b0; |
| end |
| else |
| illegal_insn_o = 1'b1; |
| ibex_defines_OPCODE_SYSTEM: |
| if (instr_rdata_i[14:12] == 3'b000) |
| case (instr_rdata_i[31:20]) |
| 12'h000: ecall_insn_o = 1'b1; |
| 12'h001: ebrk_insn_o = 1'b1; |
| 12'h302: mret_insn_o = 1'b1; |
| 12'h7b2: dret_insn_o = 1'b1; |
| 12'h105: pipe_flush_o = 1'b1; |
| default: illegal_insn_o = 1'b1; |
| endcase |
| else begin |
| csr_access_o = 1'b1; |
| regfile_we = 1'b1; |
| alu_op_b_mux_sel_o = ibex_defines_OP_B_IMM; |
| imm_a_mux_sel_o = ibex_defines_IMM_A_Z; |
| imm_b_mux_sel_o = ibex_defines_IMM_B_I; |
| if (instr_rdata_i[14]) |
| alu_op_a_mux_sel_o = ibex_defines_OP_A_IMM; |
| else |
| alu_op_a_mux_sel_o = ibex_defines_OP_A_REGA_OR_FWD; |
| case (instr_rdata_i[13:12]) |
| 2'b01: csr_op = ibex_defines_CSR_OP_WRITE; |
| 2'b10: csr_op = ibex_defines_CSR_OP_SET; |
| 2'b11: csr_op = ibex_defines_CSR_OP_CLEAR; |
| default: csr_illegal = 1'b1; |
| endcase |
| if (!csr_illegal) |
| if (((((instr_rdata_i[31:20] == ibex_defines_CSR_MSTATUS) || (instr_rdata_i[31:20] == ibex_defines_CSR_DCSR)) || (instr_rdata_i[31:20] == ibex_defines_CSR_DPC)) || (instr_rdata_i[31:20] == ibex_defines_CSR_DSCRATCH0)) || (instr_rdata_i[31:20] == ibex_defines_CSR_DSCRATCH1)) |
| csr_status_o = 1'b1; |
| illegal_insn_o = csr_illegal; |
| end |
| default: illegal_insn_o = 1'b1; |
| endcase |
| if (illegal_c_insn_i) |
| illegal_insn_o = 1'b1; |
| if (data_misaligned_i) begin |
| alu_op_a_mux_sel_o = ibex_defines_OP_A_REGA_OR_FWD; |
| alu_op_b_mux_sel_o = ibex_defines_OP_B_IMM; |
| imm_b_mux_sel_o = ibex_defines_IMM_B_PCINCR; |
| regfile_we = 1'b0; |
| end |
| end |
| assign regfile_we_o = (deassert_we_i ? 1'b0 : regfile_we); |
| assign mult_int_en_o = (RV32M ? (deassert_we_i ? 1'b0 : mult_int_en) : 1'b0); |
| assign div_int_en_o = (RV32M ? (deassert_we_i ? 1'b0 : div_int_en) : 1'b0); |
| assign data_req_o = (deassert_we_i ? 1'b0 : data_req); |
| assign csr_op_o = (deassert_we_i ? ibex_defines_CSR_OP_NONE : csr_op); |
| assign jump_in_id_o = (deassert_we_i ? 1'b0 : jump_in_id); |
| assign branch_in_id_o = (deassert_we_i ? 1'b0 : branch_in_id); |
| assign eFPGA_int_en_o = (deassert_we_i ? 1'b0 : eFPGA_int_en); |
| endmodule |
