mirror of https://github.com/YosysHQ/picorv32.git
862 lines
27 KiB
Verilog
862 lines
27 KiB
Verilog
/*
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* PicoRV32 -- A Small RISC-V (RV32I) Processor Core
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*
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* Copyright (C) 2015 Clifford Wolf <clifford@clifford.at>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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*/
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`timescale 1 ns / 1 ps
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// `define DEBUG
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/***************************************************************
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* picorv32
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***************************************************************/
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module picorv32 #(
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parameter ENABLE_COUNTERS = 1,
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parameter ENABLE_REGS_16_31 = 1
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) (
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input clk, resetn,
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output reg trap,
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output reg mem_valid,
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output reg mem_instr,
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input mem_ready,
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output reg [31:0] mem_addr,
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output reg [31:0] mem_wdata,
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output reg [ 3:0] mem_wstrb,
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input [31:0] mem_rdata,
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// look-ahead interface
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output mem_la_read,
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output [31:0] mem_la_addr
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);
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localparam integer regfile_size = ENABLE_REGS_16_31 ? 32 : 16;
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localparam integer regindex_bits = ENABLE_REGS_16_31 ? 5 : 4;
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reg [63:0] count_cycle, count_instr;
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reg [31:0] reg_pc, reg_next_pc, reg_op1, reg_op2, reg_out, reg_alu_out;
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reg [31:0] cpuregs [0:regfile_size-1];
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reg [4:0] reg_sh;
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wire [31:0] next_pc;
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// Memory Interface
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reg [1:0] mem_state;
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reg [1:0] mem_wordsize;
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reg [31:0] mem_buffer;
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reg mem_do_prefetch;
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reg mem_do_rinst;
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reg mem_do_rdata;
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reg mem_do_wdata;
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wire mem_busy = |{mem_do_prefetch, mem_do_rinst, mem_do_rdata, mem_do_wdata};
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wire mem_done = mem_ready && ((mem_state[0] && (mem_do_rinst || mem_do_rdata)) || mem_state == 2);
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assign mem_la_read = resetn && !mem_state && (mem_do_rinst || mem_do_prefetch || mem_do_rdata);
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assign mem_la_addr = mem_do_prefetch || mem_do_rinst ? next_pc : {reg_op1[31:2], 2'b00};
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always @* begin
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(* full_case *)
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case (mem_wordsize)
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0: begin
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mem_buffer = mem_rdata;
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end
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1: begin
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case (reg_op1[1])
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1'b0: mem_buffer = mem_rdata[15: 0];
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1'b1: mem_buffer = mem_rdata[31:16];
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endcase
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end
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2: begin
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case (reg_op1[1:0])
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2'b00: mem_buffer = mem_rdata[ 7: 0];
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2'b01: mem_buffer = mem_rdata[15: 8];
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2'b10: mem_buffer = mem_rdata[23:16];
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2'b11: mem_buffer = mem_rdata[31:24];
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endcase
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end
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endcase
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end
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always @(posedge clk) begin
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if (!resetn) begin
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mem_state <= 0;
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mem_valid <= 0;
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end else case (mem_state)
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0: begin
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mem_addr <= mem_la_addr;
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if (mem_do_prefetch || mem_do_rinst || mem_do_rdata) begin
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mem_valid <= 1;
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mem_instr <= mem_do_prefetch || mem_do_rinst;
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mem_wstrb <= 0;
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mem_state <= 1;
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end
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if (mem_do_wdata) begin
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mem_valid <= 1;
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mem_addr <= {reg_op1[31:2], 2'b00};
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mem_instr <= 0;
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(* full_case *)
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case (mem_wordsize)
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0: begin
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mem_wdata <= reg_op2;
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mem_wstrb <= 4'b1111;
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end
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1: begin
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mem_wdata <= {2{reg_op2[15:0]}};
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mem_wstrb <= reg_op1[1] ? 4'b1100 : 4'b0011;
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end
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2: begin
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mem_wdata <= {4{reg_op2[7:0]}};
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mem_wstrb <= 4'b0001 << reg_op1[1:0];
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end
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endcase
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mem_state <= 2;
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end
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end
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1: begin
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if (mem_ready) begin
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mem_valid <= 0;
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mem_state <= mem_do_rinst || mem_do_rdata ? 0 : 3;
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end
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end
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2: begin
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if (mem_ready) begin
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mem_valid <= 0;
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mem_state <= 0;
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end
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end
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3: begin
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if (mem_do_rinst) begin
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mem_state <= 0;
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end
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end
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endcase
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end
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// Instruction Decoder
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reg instr_lui, instr_auipc, instr_jal, instr_jalr;
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reg instr_beq, instr_bne, instr_blt, instr_bge, instr_bltu, instr_bgeu;
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reg instr_lb, instr_lh, instr_lw, instr_lbu, instr_lhu, instr_sb, instr_sh, instr_sw;
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reg instr_addi, instr_slti, instr_sltiu, instr_xori, instr_ori, instr_andi, instr_slli, instr_srli, instr_srai;
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reg instr_add, instr_sub, instr_sll, instr_slt, instr_sltu, instr_xor, instr_srl, instr_sra, instr_or, instr_and;
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reg instr_rdcycle, instr_rdcycleh, instr_rdinstr, instr_rdinstrh;
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wire instr_trap;
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reg [regindex_bits-1:0] decoded_rd, decoded_rs1, decoded_rs2;
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reg [31:0] decoded_imm;
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reg decoder_trigger;
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wire [31:0] decoded_imm_uj;
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assign { decoded_imm_uj[31:20], decoded_imm_uj[10:1], decoded_imm_uj[11], decoded_imm_uj[19:12], decoded_imm_uj[0] } = $signed({mem_rdata[31:12], 1'b0});
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reg is_lui_auipc_jal;
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reg is_lb_lh_lw_lbu_lhu;
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reg is_slli_srli_srai;
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reg is_jalr_addi_slti_sltiu_xori_ori_andi;
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reg is_sb_sh_sw;
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reg is_sll_srl_sra;
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reg is_lui_auipc_jal_jalr_addi_add;
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reg is_slti_blt_slt;
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reg is_sltiu_bltu_sltu;
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reg is_beq_bne_blt_bge_bltu_bgeu;
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reg is_lbu_lhu_lw;
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always @(posedge clk) begin
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is_lui_auipc_jal <= |{instr_lui, instr_auipc, instr_jal};
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is_lb_lh_lw_lbu_lhu <= |{instr_lb, instr_lh, instr_lw, instr_lbu, instr_lhu};
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is_slli_srli_srai <= |{instr_slli, instr_srli, instr_srai};
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is_jalr_addi_slti_sltiu_xori_ori_andi <= |{instr_jalr, instr_addi, instr_slti, instr_sltiu, instr_xori, instr_ori, instr_andi};
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is_sb_sh_sw <= |{instr_sb, instr_sh, instr_sw};
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is_sll_srl_sra <= |{instr_sll, instr_srl, instr_sra};
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is_lui_auipc_jal_jalr_addi_add <= |{instr_lui, instr_auipc, instr_jal, instr_jalr, instr_addi, instr_add};
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is_slti_blt_slt <= |{instr_slti, instr_blt, instr_slt};
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is_sltiu_bltu_sltu <= |{instr_sltiu, instr_bltu, instr_sltu};
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is_beq_bne_blt_bge_bltu_bgeu <= |{instr_beq, instr_bne, instr_blt, instr_bge, instr_bltu, instr_bgeu};
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is_lbu_lhu_lw <= |{instr_lbu, instr_lhu, instr_lw};
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end
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assign instr_trap = !{instr_lui, instr_auipc, instr_jal, instr_jalr,
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instr_beq, instr_bne, instr_blt, instr_bge, instr_bltu, instr_bgeu,
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instr_lb, instr_lh, instr_lw, instr_lbu, instr_lhu, instr_sb, instr_sh, instr_sw,
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instr_addi, instr_slti, instr_sltiu, instr_xori, instr_ori, instr_andi, instr_slli, instr_srli, instr_srai,
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instr_add, instr_sub, instr_sll, instr_slt, instr_sltu, instr_xor, instr_srl, instr_sra, instr_or, instr_and,
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instr_rdcycle, instr_rdcycleh, instr_rdinstr, instr_rdinstrh};
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reg [63:0] instruction;
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always @* begin
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instruction = 'bx;
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if (instr_lui) instruction = "lui";
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if (instr_auipc) instruction = "auipc";
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if (instr_jal) instruction = "jal";
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if (instr_jalr) instruction = "jalr";
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if (instr_beq) instruction = "beq";
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if (instr_bne) instruction = "bne";
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if (instr_blt) instruction = "blt";
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if (instr_bge) instruction = "bge";
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if (instr_bltu) instruction = "bltu";
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if (instr_bgeu) instruction = "bgeu";
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if (instr_lb) instruction = "lb";
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if (instr_lh) instruction = "lh";
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if (instr_lw) instruction = "lw";
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if (instr_lbu) instruction = "lbu";
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if (instr_lhu) instruction = "lhu";
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if (instr_sb) instruction = "sb";
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if (instr_sh) instruction = "sh";
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if (instr_sw) instruction = "sw";
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if (instr_addi) instruction = "addi";
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if (instr_slti) instruction = "slti";
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if (instr_sltiu) instruction = "sltiu";
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if (instr_xori) instruction = "xori";
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if (instr_ori) instruction = "ori";
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if (instr_andi) instruction = "andi";
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if (instr_slli) instruction = "slli";
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if (instr_srli) instruction = "srli";
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if (instr_srai) instruction = "srai";
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if (instr_add) instruction = "add";
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if (instr_sub) instruction = "sub";
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if (instr_sll) instruction = "sll";
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if (instr_slt) instruction = "slt";
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if (instr_sltu) instruction = "sltu";
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if (instr_xor) instruction = "xor";
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if (instr_srl) instruction = "srl";
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if (instr_sra) instruction = "sra";
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if (instr_or) instruction = "or";
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if (instr_and) instruction = "and";
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if (instr_rdcycle) instruction = "rdcycle";
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if (instr_rdcycleh) instruction = "rdcycleh";
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if (instr_rdinstr) instruction = "rdinstr";
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if (instr_rdinstrh) instruction = "rdinstrh";
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end
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always @(posedge clk) begin
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decoder_trigger <= 0;
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if (mem_do_rinst && mem_done) begin
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instr_lui <= mem_rdata[6:0] == 7'b0110111;
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instr_auipc <= mem_rdata[6:0] == 7'b0010111;
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instr_jal <= mem_rdata[6:0] == 7'b1101111;
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instr_jalr <= mem_rdata[6:0] == 7'b1100111;
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instr_beq <= mem_rdata[6:0] == 7'b1100011 && mem_rdata[14:12] == 3'b000;
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instr_bne <= mem_rdata[6:0] == 7'b1100011 && mem_rdata[14:12] == 3'b001;
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instr_blt <= mem_rdata[6:0] == 7'b1100011 && mem_rdata[14:12] == 3'b100;
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instr_bge <= mem_rdata[6:0] == 7'b1100011 && mem_rdata[14:12] == 3'b101;
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instr_bltu <= mem_rdata[6:0] == 7'b1100011 && mem_rdata[14:12] == 3'b110;
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instr_bgeu <= mem_rdata[6:0] == 7'b1100011 && mem_rdata[14:12] == 3'b111;
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instr_lb <= mem_rdata[6:0] == 7'b0000011 && mem_rdata[14:12] == 3'b000;
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instr_lh <= mem_rdata[6:0] == 7'b0000011 && mem_rdata[14:12] == 3'b001;
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instr_lw <= mem_rdata[6:0] == 7'b0000011 && mem_rdata[14:12] == 3'b010;
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instr_lbu <= mem_rdata[6:0] == 7'b0000011 && mem_rdata[14:12] == 3'b100;
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instr_lhu <= mem_rdata[6:0] == 7'b0000011 && mem_rdata[14:12] == 3'b101;
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instr_sb <= mem_rdata[6:0] == 7'b0100011 && mem_rdata[14:12] == 3'b000;
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instr_sh <= mem_rdata[6:0] == 7'b0100011 && mem_rdata[14:12] == 3'b001;
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instr_sw <= mem_rdata[6:0] == 7'b0100011 && mem_rdata[14:12] == 3'b010;
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instr_addi <= mem_rdata[6:0] == 7'b0010011 && mem_rdata[14:12] == 3'b000;
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instr_slti <= mem_rdata[6:0] == 7'b0010011 && mem_rdata[14:12] == 3'b010;
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instr_sltiu <= mem_rdata[6:0] == 7'b0010011 && mem_rdata[14:12] == 3'b011;
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instr_xori <= mem_rdata[6:0] == 7'b0010011 && mem_rdata[14:12] == 3'b100;
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instr_ori <= mem_rdata[6:0] == 7'b0010011 && mem_rdata[14:12] == 3'b110;
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instr_andi <= mem_rdata[6:0] == 7'b0010011 && mem_rdata[14:12] == 3'b111;
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instr_slli <= mem_rdata[6:0] == 7'b0010011 && mem_rdata[14:12] == 3'b001 && mem_rdata[31:25] == 7'b0000000;
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instr_srli <= mem_rdata[6:0] == 7'b0010011 && mem_rdata[14:12] == 3'b101 && mem_rdata[31:25] == 7'b0000000;
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instr_srai <= mem_rdata[6:0] == 7'b0010011 && mem_rdata[14:12] == 3'b101 && mem_rdata[31:25] == 7'b0100000;
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instr_add <= mem_rdata[6:0] == 7'b0110011 && mem_rdata[14:12] == 3'b000 && mem_rdata[31:25] == 7'b0000000;
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instr_sub <= mem_rdata[6:0] == 7'b0110011 && mem_rdata[14:12] == 3'b000 && mem_rdata[31:25] == 7'b0100000;
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instr_sll <= mem_rdata[6:0] == 7'b0110011 && mem_rdata[14:12] == 3'b001 && mem_rdata[31:25] == 7'b0000000;
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instr_slt <= mem_rdata[6:0] == 7'b0110011 && mem_rdata[14:12] == 3'b010 && mem_rdata[31:25] == 7'b0000000;
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instr_sltu <= mem_rdata[6:0] == 7'b0110011 && mem_rdata[14:12] == 3'b011 && mem_rdata[31:25] == 7'b0000000;
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instr_xor <= mem_rdata[6:0] == 7'b0110011 && mem_rdata[14:12] == 3'b100 && mem_rdata[31:25] == 7'b0000000;
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instr_srl <= mem_rdata[6:0] == 7'b0110011 && mem_rdata[14:12] == 3'b101 && mem_rdata[31:25] == 7'b0000000;
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instr_sra <= mem_rdata[6:0] == 7'b0110011 && mem_rdata[14:12] == 3'b101 && mem_rdata[31:25] == 7'b0100000;
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instr_or <= mem_rdata[6:0] == 7'b0110011 && mem_rdata[14:12] == 3'b110 && mem_rdata[31:25] == 7'b0000000;
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instr_and <= mem_rdata[6:0] == 7'b0110011 && mem_rdata[14:12] == 3'b111 && mem_rdata[31:25] == 7'b0000000;
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instr_rdcycle <= ((mem_rdata[6:0] == 7'b1110011 && mem_rdata[31:12] == 'b11000000000000000010) ||
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(mem_rdata[6:0] == 7'b1110011 && mem_rdata[31:12] == 'b11000000000100000010)) && ENABLE_COUNTERS;
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instr_rdcycleh <= ((mem_rdata[6:0] == 7'b1110011 && mem_rdata[31:12] == 'b11001000000000000010) ||
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(mem_rdata[6:0] == 7'b1110011 && mem_rdata[31:12] == 'b11001000000100000010)) && ENABLE_COUNTERS;
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instr_rdinstr <= (mem_rdata[6:0] == 7'b1110011 && mem_rdata[31:12] == 'b11000000001000000010) && ENABLE_COUNTERS;
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instr_rdinstrh <= (mem_rdata[6:0] == 7'b1110011 && mem_rdata[31:12] == 'b11001000001000000010) && ENABLE_COUNTERS;
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decoded_rd <= mem_rdata[11:7];
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decoded_rs1 <= mem_rdata[19:15];
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decoded_rs2 <= mem_rdata[24:20];
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decoder_trigger <= 1;
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end
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if (decoder_trigger) begin
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(* parallel_case *)
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case (1'b1)
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|{instr_lui, instr_auipc}:
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decoded_imm <= mem_rdata[31:12] << 12;
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instr_jal:
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decoded_imm <= decoded_imm_uj;
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instr_jalr:
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decoded_imm <= $signed(mem_rdata[31:20]);
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|{instr_beq, instr_bne, instr_blt, instr_bge, instr_bltu, instr_bgeu}:
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decoded_imm <= $signed({mem_rdata[31], mem_rdata[7], mem_rdata[30:25], mem_rdata[11:8], 1'b0});
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|{instr_lb, instr_lh, instr_lw, instr_lbu, instr_lhu}:
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decoded_imm <= $signed(mem_rdata[31:20]);
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|{instr_sb, instr_sh, instr_sw}:
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decoded_imm <= $signed({mem_rdata[31:25], mem_rdata[11:7]});
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|{instr_addi, instr_slti, instr_sltiu, instr_xori, instr_ori, instr_andi}:
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decoded_imm <= $signed(mem_rdata[31:20]);
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default:
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decoded_imm <= 1'bx;
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endcase
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end
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end
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// Main State Machine
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localparam cpu_state_trap = 0;
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localparam cpu_state_fetch = 1;
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localparam cpu_state_ld_rs1 = 2;
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localparam cpu_state_ld_rs2 = 3;
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localparam cpu_state_exec = 4;
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localparam cpu_state_shift = 5;
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localparam cpu_state_stmem = 6;
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localparam cpu_state_ldmem = 7;
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reg [2:0] cpu_state;
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reg set_mem_do_rinst;
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reg set_mem_do_rdata;
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reg set_mem_do_wdata;
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reg mask_decoder_trigger;
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reg force_decoder_trigger;
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reg latched_store;
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reg latched_stalu;
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reg latched_branch;
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reg latched_is_lu;
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reg latched_is_lh;
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reg latched_is_lb;
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reg [regindex_bits-1:0] latched_rd;
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|
|
reg [31:0] current_pc;
|
|
assign next_pc = latched_store && latched_branch ? reg_out : reg_next_pc;
|
|
|
|
reg [31:0] alu_out;
|
|
reg alu_out_0;
|
|
|
|
always @* begin
|
|
alu_out_0 = 'bx;
|
|
(* parallel_case, full_case *)
|
|
case (1'b1)
|
|
instr_beq:
|
|
alu_out_0 = reg_op1 == reg_op2;
|
|
instr_bne:
|
|
alu_out_0 = reg_op1 != reg_op2;
|
|
instr_bge:
|
|
alu_out_0 = $signed(reg_op1) >= $signed(reg_op2);
|
|
instr_bgeu:
|
|
alu_out_0 = reg_op1 >= reg_op2;
|
|
is_slti_blt_slt:
|
|
alu_out_0 = $signed(reg_op1) < $signed(reg_op2);
|
|
is_sltiu_bltu_sltu:
|
|
alu_out_0 = reg_op1 < reg_op2;
|
|
endcase
|
|
|
|
alu_out = 'bx;
|
|
(* parallel_case, full_case *)
|
|
case (1'b1)
|
|
is_lui_auipc_jal_jalr_addi_add:
|
|
alu_out = reg_op1 + reg_op2;
|
|
instr_sub:
|
|
alu_out = reg_op1 - reg_op2;
|
|
|{instr_beq, instr_bne, instr_bge, instr_bgeu, is_slti_blt_slt, is_sltiu_bltu_sltu}:
|
|
alu_out = alu_out_0;
|
|
instr_xori || instr_xor:
|
|
alu_out = reg_op1 ^ reg_op2;
|
|
instr_ori || instr_or:
|
|
alu_out = reg_op1 | reg_op2;
|
|
instr_andi || instr_and:
|
|
alu_out = reg_op1 & reg_op2;
|
|
endcase
|
|
end
|
|
|
|
always @(posedge clk) begin
|
|
trap <= 0;
|
|
reg_sh <= 'bx;
|
|
reg_out <= 'bx;
|
|
set_mem_do_rinst = 0;
|
|
set_mem_do_rdata = 0;
|
|
set_mem_do_wdata = 0;
|
|
mask_decoder_trigger <= 0;
|
|
force_decoder_trigger <= 0;
|
|
|
|
reg_alu_out <= alu_out;
|
|
|
|
if (ENABLE_COUNTERS)
|
|
count_cycle <= resetn ? count_cycle + 1 : 0;
|
|
|
|
if (!resetn) begin
|
|
reg_pc <= 0;
|
|
reg_next_pc <= 0;
|
|
reg_op1 <= 'bx;
|
|
reg_op2 <= 'bx;
|
|
if (ENABLE_COUNTERS)
|
|
count_instr <= 0;
|
|
latched_store <= 0;
|
|
latched_stalu <= 0;
|
|
latched_branch <= 0;
|
|
latched_is_lu <= 0;
|
|
latched_is_lh <= 0;
|
|
latched_is_lb <= 0;
|
|
cpu_state <= cpu_state_fetch;
|
|
end else
|
|
(* parallel_case, full_case *)
|
|
case (cpu_state)
|
|
cpu_state_trap: begin
|
|
trap <= 1;
|
|
end
|
|
cpu_state_fetch: begin
|
|
mem_do_rinst <= (!decoder_trigger || mask_decoder_trigger) && !force_decoder_trigger;
|
|
mem_wordsize <= 0;
|
|
|
|
current_pc = reg_next_pc;
|
|
|
|
if (latched_branch) begin
|
|
current_pc = latched_store ? (latched_stalu ? reg_alu_out : reg_out) : reg_next_pc;
|
|
`ifdef DEBUG
|
|
$display("ST_RD: %2d 0x%08x, BRANCH 0x%08x", latched_rd, reg_pc + 4, current_pc);
|
|
`endif
|
|
cpuregs[latched_rd] <= reg_pc + 4;
|
|
end else
|
|
if (latched_store) begin
|
|
`ifdef DEBUG
|
|
$display("ST_RD: %2d 0x%08x", latched_rd, reg_out);
|
|
`endif
|
|
cpuregs[latched_rd] <= latched_stalu ? reg_alu_out : reg_out;
|
|
end
|
|
|
|
reg_pc <= current_pc;
|
|
reg_next_pc <= current_pc;
|
|
|
|
latched_store <= 0;
|
|
latched_stalu <= 0;
|
|
latched_branch <= 0;
|
|
latched_is_lu <= 0;
|
|
latched_is_lh <= 0;
|
|
latched_is_lb <= 0;
|
|
latched_rd <= decoded_rd;
|
|
|
|
if ((decoder_trigger && !mask_decoder_trigger) || force_decoder_trigger) begin
|
|
`ifdef DEBUG
|
|
$display("DECODE: 0x%08x %-s", current_pc, instruction);
|
|
`endif
|
|
reg_next_pc <= current_pc + 4;
|
|
|
|
if (instr_trap) begin
|
|
`ifdef DEBUG
|
|
$display("SBREAK OR UNSUPPORTED INSN AT 0x%08x", current_pc);
|
|
`endif
|
|
cpu_state <= cpu_state_trap;
|
|
end else if (instr_jal) begin
|
|
mem_do_rinst <= 1;
|
|
if (latched_is_lu || latched_is_lh || latched_is_lb)
|
|
reg_next_pc <= current_pc + decoded_imm;
|
|
else
|
|
reg_next_pc <= current_pc + decoded_imm_uj;
|
|
latched_branch <= 1;
|
|
end else if (|{instr_rdcycle, instr_rdcycleh, instr_rdinstr, instr_rdinstrh}) begin
|
|
(* parallel_case, full_case *)
|
|
case (1'b1)
|
|
instr_rdcycle:
|
|
reg_out <= count_cycle[31:0];
|
|
instr_rdcycleh:
|
|
reg_out <= count_cycle[63:32];
|
|
instr_rdinstr:
|
|
reg_out <= count_instr[31:0];
|
|
instr_rdinstrh:
|
|
reg_out <= count_instr[63:32];
|
|
endcase
|
|
latched_store <= 1;
|
|
end else begin
|
|
mem_do_rinst <= 0;
|
|
mem_do_prefetch <= !instr_jalr;
|
|
cpu_state <= cpu_state_ld_rs1;
|
|
end
|
|
if (ENABLE_COUNTERS)
|
|
count_instr <= count_instr + 1;
|
|
end
|
|
end
|
|
cpu_state_ld_rs1: begin
|
|
if (is_lui_auipc_jal) begin
|
|
reg_op1 <= instr_lui ? 0 : reg_pc;
|
|
reg_op2 <= decoded_imm;
|
|
mem_do_rinst <= mem_do_prefetch;
|
|
cpu_state <= cpu_state_exec;
|
|
end else begin
|
|
`ifdef DEBUG
|
|
$display("LD_RS1: %2d 0x%08x", decoded_rs1, decoded_rs1 ? cpuregs[decoded_rs1] : 0);
|
|
`endif
|
|
reg_op1 <= decoded_rs1 ? cpuregs[decoded_rs1] : 0;
|
|
if (is_lb_lh_lw_lbu_lhu) begin
|
|
cpu_state <= cpu_state_ldmem;
|
|
mem_do_rinst <= 1;
|
|
end else if (is_slli_srli_srai) begin
|
|
reg_sh <= decoded_rs2;
|
|
cpu_state <= cpu_state_shift;
|
|
end else if (is_jalr_addi_slti_sltiu_xori_ori_andi) begin
|
|
reg_op2 <= decoded_imm;
|
|
mem_do_rinst <= mem_do_prefetch;
|
|
cpu_state <= cpu_state_exec;
|
|
end else
|
|
cpu_state <= cpu_state_ld_rs2;
|
|
end
|
|
end
|
|
cpu_state_ld_rs2: begin
|
|
`ifdef DEBUG
|
|
$display("LD_RS2: %2d 0x%08x", decoded_rs2, decoded_rs2 ? cpuregs[decoded_rs2] : 0);
|
|
`endif
|
|
reg_op2 <= decoded_rs2 ? cpuregs[decoded_rs2] : 0;
|
|
if (is_sb_sh_sw) begin
|
|
cpu_state <= cpu_state_stmem;
|
|
mem_do_rinst <= 1;
|
|
end else if (is_sll_srl_sra) begin
|
|
reg_sh <= decoded_rs2 ? cpuregs[decoded_rs2] : 0;
|
|
cpu_state <= cpu_state_shift;
|
|
end else begin
|
|
mem_do_rinst <= mem_do_prefetch;
|
|
cpu_state <= cpu_state_exec;
|
|
end
|
|
end
|
|
cpu_state_exec: begin
|
|
reg_out <= reg_pc + decoded_imm;
|
|
if (is_beq_bne_blt_bge_bltu_bgeu) begin
|
|
latched_rd <= 0;
|
|
if (mem_done)
|
|
cpu_state <= cpu_state_fetch;
|
|
if (alu_out_0) begin
|
|
latched_store <= 1;
|
|
latched_branch <= 1;
|
|
mask_decoder_trigger <= 1;
|
|
set_mem_do_rinst = 1;
|
|
end
|
|
end else begin
|
|
latched_branch <= instr_jalr;
|
|
latched_store <= 1;
|
|
latched_stalu <= 1;
|
|
cpu_state <= cpu_state_fetch;
|
|
end
|
|
end
|
|
cpu_state_shift: begin
|
|
if (reg_sh == 0) begin
|
|
reg_out <= reg_op1;
|
|
mem_do_rinst <= mem_do_prefetch;
|
|
latched_store <= 1;
|
|
cpu_state <= cpu_state_fetch;
|
|
end else if (reg_sh >= 4) begin
|
|
(* parallel_case, full_case *)
|
|
case (1'b1)
|
|
instr_slli || instr_sll: reg_op1 <= reg_op1 << 4;
|
|
instr_srli || instr_srl: reg_op1 <= reg_op1 >> 4;
|
|
instr_srai || instr_sra: reg_op1 <= $signed(reg_op1) >>> 4;
|
|
endcase
|
|
reg_sh <= reg_sh - 4;
|
|
end else begin
|
|
(* parallel_case, full_case *)
|
|
case (1'b1)
|
|
instr_slli || instr_sll: reg_op1 <= reg_op1 << 1;
|
|
instr_srli || instr_srl: reg_op1 <= reg_op1 >> 1;
|
|
instr_srai || instr_sra: reg_op1 <= $signed(reg_op1) >>> 1;
|
|
endcase
|
|
reg_sh <= reg_sh - 1;
|
|
end
|
|
end
|
|
cpu_state_stmem: begin
|
|
if (!mem_do_prefetch || mem_done) begin
|
|
if (!mem_do_wdata) begin
|
|
(* parallel_case, full_case *)
|
|
case (1'b1)
|
|
instr_sb: mem_wordsize <= 2;
|
|
instr_sh: mem_wordsize <= 1;
|
|
instr_sw: mem_wordsize <= 0;
|
|
endcase
|
|
reg_op1 <= reg_op1 + decoded_imm;
|
|
set_mem_do_wdata = 1;
|
|
end
|
|
if (!mem_do_prefetch && mem_done) begin
|
|
cpu_state <= cpu_state_fetch;
|
|
force_decoder_trigger <= 1;
|
|
end
|
|
end
|
|
end
|
|
cpu_state_ldmem: begin
|
|
if (!mem_do_prefetch || mem_done) begin
|
|
if (!mem_do_rdata) begin
|
|
(* parallel_case, full_case *)
|
|
case (1'b1)
|
|
instr_lb || instr_lbu: mem_wordsize <= 2;
|
|
instr_lh || instr_lhu: mem_wordsize <= 1;
|
|
instr_lw: mem_wordsize <= 0;
|
|
endcase
|
|
latched_store <= 1;
|
|
latched_is_lu <= is_lbu_lhu_lw;
|
|
latched_is_lh <= instr_lh;
|
|
latched_is_lb <= instr_lb;
|
|
reg_op1 <= reg_op1 + decoded_imm;
|
|
set_mem_do_rdata = 1;
|
|
end
|
|
if (!mem_do_prefetch && mem_done) begin
|
|
(* parallel_case, full_case *)
|
|
case (1'b1)
|
|
latched_is_lu: reg_out <= mem_buffer;
|
|
latched_is_lh: reg_out <= $signed(mem_buffer[15:0]);
|
|
latched_is_lb: reg_out <= $signed(mem_buffer[7:0]);
|
|
endcase
|
|
force_decoder_trigger <= 1;
|
|
cpu_state <= cpu_state_fetch;
|
|
end
|
|
end
|
|
end
|
|
endcase
|
|
|
|
if (resetn && (mem_do_rdata || mem_do_wdata)) begin
|
|
if (mem_wordsize == 0 && reg_op1[1:0] != 0) begin
|
|
`ifdef DEBUG
|
|
$display("MISALIGNED WORD: 0x%08x", reg_op1);
|
|
`endif
|
|
cpu_state <= cpu_state_trap;
|
|
end
|
|
if (mem_wordsize == 1 && reg_op1[0] != 0) begin
|
|
`ifdef DEBUG
|
|
$display("MISALIGNED HALFWORD: 0x%08x", reg_op1);
|
|
`endif
|
|
cpu_state <= cpu_state_trap;
|
|
end
|
|
end
|
|
if (resetn && mem_do_rinst && reg_pc[1:0] != 0) begin
|
|
`ifdef DEBUG
|
|
$display("MISALIGNED INSTRUCTION: 0x%08x", reg_pc);
|
|
`endif
|
|
cpu_state <= cpu_state_trap;
|
|
end
|
|
|
|
if (!resetn || mem_done) begin
|
|
mem_do_prefetch <= 0;
|
|
mem_do_rinst <= 0;
|
|
mem_do_rdata <= 0;
|
|
mem_do_wdata <= 0;
|
|
end
|
|
|
|
if (set_mem_do_rinst)
|
|
mem_do_rinst <= 1;
|
|
if (set_mem_do_rdata)
|
|
mem_do_rdata <= 1;
|
|
if (set_mem_do_wdata)
|
|
mem_do_wdata <= 1;
|
|
|
|
reg_pc[1:0] <= 0;
|
|
reg_next_pc[1:0] <= 0;
|
|
current_pc = 'bx;
|
|
end
|
|
endmodule
|
|
|
|
|
|
/***************************************************************
|
|
* picorv32_axi
|
|
***************************************************************/
|
|
|
|
module picorv32_axi #(
|
|
parameter ENABLE_COUNTERS = 1,
|
|
parameter ENABLE_REGS_16_31 = 1
|
|
) (
|
|
input clk, resetn,
|
|
output trap,
|
|
|
|
// AXI4-lite master memory interface
|
|
|
|
output mem_axi_awvalid,
|
|
input mem_axi_awready,
|
|
output [31:0] mem_axi_awaddr,
|
|
output [ 2:0] mem_axi_awprot,
|
|
|
|
output mem_axi_wvalid,
|
|
input mem_axi_wready,
|
|
output [31:0] mem_axi_wdata,
|
|
output [ 3:0] mem_axi_wstrb,
|
|
|
|
input mem_axi_bvalid,
|
|
output mem_axi_bready,
|
|
|
|
output mem_axi_arvalid,
|
|
input mem_axi_arready,
|
|
output [31:0] mem_axi_araddr,
|
|
output [ 2:0] mem_axi_arprot,
|
|
|
|
input mem_axi_rvalid,
|
|
output mem_axi_rready,
|
|
input [31:0] mem_axi_rdata
|
|
);
|
|
wire mem_valid;
|
|
wire [31:0] mem_addr;
|
|
wire [31:0] mem_wdata;
|
|
wire [ 3:0] mem_wstrb;
|
|
wire mem_instr;
|
|
wire mem_ready;
|
|
wire [31:0] mem_rdata;
|
|
|
|
picorv32_axi_adapter axi_adapter (
|
|
.clk (clk ),
|
|
.resetn (resetn ),
|
|
.mem_axi_awvalid(mem_axi_awvalid),
|
|
.mem_axi_awready(mem_axi_awready),
|
|
.mem_axi_awaddr (mem_axi_awaddr ),
|
|
.mem_axi_awprot (mem_axi_awprot ),
|
|
.mem_axi_wvalid (mem_axi_wvalid ),
|
|
.mem_axi_wready (mem_axi_wready ),
|
|
.mem_axi_wdata (mem_axi_wdata ),
|
|
.mem_axi_wstrb (mem_axi_wstrb ),
|
|
.mem_axi_bvalid (mem_axi_bvalid ),
|
|
.mem_axi_bready (mem_axi_bready ),
|
|
.mem_axi_arvalid(mem_axi_arvalid),
|
|
.mem_axi_arready(mem_axi_arready),
|
|
.mem_axi_araddr (mem_axi_araddr ),
|
|
.mem_axi_arprot (mem_axi_arprot ),
|
|
.mem_axi_rvalid (mem_axi_rvalid ),
|
|
.mem_axi_rready (mem_axi_rready ),
|
|
.mem_axi_rdata (mem_axi_rdata ),
|
|
.mem_valid (mem_valid ),
|
|
.mem_instr (mem_instr ),
|
|
.mem_ready (mem_ready ),
|
|
.mem_addr (mem_addr ),
|
|
.mem_wdata (mem_wdata ),
|
|
.mem_wstrb (mem_wstrb ),
|
|
.mem_rdata (mem_rdata )
|
|
);
|
|
|
|
picorv32 #(
|
|
.ENABLE_COUNTERS (ENABLE_COUNTERS ),
|
|
.ENABLE_REGS_16_31(ENABLE_REGS_16_31)
|
|
) picorv32_core (
|
|
.clk (clk ),
|
|
.resetn (resetn ),
|
|
.trap (trap ),
|
|
.mem_valid(mem_valid),
|
|
.mem_addr (mem_addr ),
|
|
.mem_wdata(mem_wdata),
|
|
.mem_wstrb(mem_wstrb),
|
|
.mem_instr(mem_instr),
|
|
.mem_ready(mem_ready),
|
|
.mem_rdata(mem_rdata)
|
|
);
|
|
endmodule
|
|
|
|
|
|
/***************************************************************
|
|
* picorv32_axi_adapter
|
|
***************************************************************/
|
|
|
|
module picorv32_axi_adapter (
|
|
input clk, resetn,
|
|
|
|
// AXI4-lite master memory interface
|
|
|
|
output mem_axi_awvalid,
|
|
input mem_axi_awready,
|
|
output [31:0] mem_axi_awaddr,
|
|
output [ 2:0] mem_axi_awprot,
|
|
|
|
output mem_axi_wvalid,
|
|
input mem_axi_wready,
|
|
output [31:0] mem_axi_wdata,
|
|
output [ 3:0] mem_axi_wstrb,
|
|
|
|
input mem_axi_bvalid,
|
|
output mem_axi_bready,
|
|
|
|
output mem_axi_arvalid,
|
|
input mem_axi_arready,
|
|
output [31:0] mem_axi_araddr,
|
|
output [ 2:0] mem_axi_arprot,
|
|
|
|
input mem_axi_rvalid,
|
|
output mem_axi_rready,
|
|
input [31:0] mem_axi_rdata,
|
|
|
|
// Native PicoRV32 memory interface
|
|
|
|
input mem_valid,
|
|
input mem_instr,
|
|
output mem_ready,
|
|
input [31:0] mem_addr,
|
|
input [31:0] mem_wdata,
|
|
input [ 3:0] mem_wstrb,
|
|
output [31:0] mem_rdata
|
|
);
|
|
reg ack_awvalid;
|
|
reg ack_arvalid;
|
|
reg ack_wvalid;
|
|
|
|
assign mem_axi_awvalid = mem_valid && |mem_wstrb && !ack_awvalid;
|
|
assign mem_axi_awaddr = mem_addr;
|
|
assign mem_axi_awprot = 0;
|
|
|
|
assign mem_axi_arvalid = mem_valid && !mem_wstrb && !ack_arvalid;
|
|
assign mem_axi_araddr = mem_addr;
|
|
assign mem_axi_arprot = mem_instr ? 3'b100 : 3'b000;
|
|
|
|
assign mem_axi_wvalid = mem_valid && |mem_wstrb && !ack_wvalid;
|
|
assign mem_axi_wdata = mem_wdata;
|
|
assign mem_axi_wstrb = mem_wstrb;
|
|
|
|
assign mem_ready = mem_axi_bvalid || mem_axi_rvalid;
|
|
assign mem_axi_bready = mem_valid && |mem_wstrb;
|
|
assign mem_axi_rready = mem_valid && !mem_wstrb;
|
|
assign mem_rdata = mem_axi_rdata;
|
|
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always @(posedge clk) begin
|
|
if (!resetn) begin
|
|
ack_awvalid <= 0;
|
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end else begin
|
|
if (mem_axi_awready && mem_axi_awvalid)
|
|
ack_awvalid <= 1;
|
|
if (mem_axi_arready && mem_axi_arvalid)
|
|
ack_arvalid <= 1;
|
|
if (mem_axi_wready && mem_axi_wvalid)
|
|
ack_wvalid <= 1;
|
|
if (!mem_valid) begin
|
|
ack_awvalid <= 0;
|
|
ack_arvalid <= 0;
|
|
ack_wvalid <= 0;
|
|
end
|
|
end
|
|
end
|
|
endmodule
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|
|