/*
 *  PicoRV32 -- A Small RISC-V (RV32I) Processor Core
 *
 *  Copyright (C) 2015  Clifford Wolf <clifford@clifford.at>
 *
 *  Permission to use, copy, modify, and/or distribute this software for any
 *  purpose with or without fee is hereby granted, provided that the above
 *  copyright notice and this permission notice appear in all copies.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 */

`timescale 1 ns / 1 ps
// `define DEBUG

`ifdef DEBUG
  `define debug(debug_command) debug_command
`else
  `define debug(debug_command)
`endif


/***************************************************************
 * picorv32
 ***************************************************************/

module picorv32 #(
	parameter [ 0:0] ENABLE_COUNTERS = 1,
	parameter [ 0:0] ENABLE_REGS_16_31 = 1,
	parameter [ 0:0] ENABLE_REGS_DUALPORT = 1,
	parameter [ 0:0] LATCHED_MEM_RDATA = 0,
	parameter [ 0:0] TWO_STAGE_SHIFT = 1,
	parameter [ 0:0] TWO_CYCLE_COMPARE = 0,
	parameter [ 0:0] CATCH_MISALIGN = 1,
	parameter [ 0:0] CATCH_ILLINSN = 1,
	parameter [ 0:0] ENABLE_PCPI = 0,
	parameter [ 0:0] ENABLE_MUL = 0,
	parameter [ 0:0] ENABLE_IRQ = 0,
	parameter [ 0:0] ENABLE_IRQ_QREGS = 1,
	parameter [ 0:0] ENABLE_IRQ_TIMER = 1,
	parameter [31:0] MASKED_IRQ = 32'h 0000_0000,
	parameter [31:0] LATCHED_IRQ = 32'h ffff_ffff,
	parameter [31:0] PROGADDR_RESET = 32'h 0000_0000,
	parameter [31:0] PROGADDR_IRQ = 32'h 0000_0010
) (
	input clk, resetn,
	output reg trap,

	output reg        mem_valid,
	output reg        mem_instr,
	input             mem_ready,

	output reg [31:0] mem_addr,
	output reg [31:0] mem_wdata,
	output reg [ 3:0] mem_wstrb,
	input      [31:0] mem_rdata,

	// Look-Ahead Interface
	output            mem_la_read,
	output            mem_la_write,
	output     [31:0] mem_la_addr,
	output reg [31:0] mem_la_wdata,
	output reg [ 3:0] mem_la_wstrb,

	// Pico Co-Processor Interface (PCPI)
	output reg        pcpi_valid,
	output reg [31:0] pcpi_insn,
	output     [31:0] pcpi_rs1,
	output     [31:0] pcpi_rs2,
	input             pcpi_wr,
	input      [31:0] pcpi_rd,
	input             pcpi_wait,
	input             pcpi_ready,

	// IRQ Interface
	input      [31:0] irq,
	output reg [31:0] eoi
);
	localparam integer irq_timer = 0;
	localparam integer irq_sbreak = 1;
	localparam integer irq_buserror = 2;

	localparam integer irqregs_offset = ENABLE_REGS_16_31 ? 32 : 16;
	localparam integer regfile_size = (ENABLE_REGS_16_31 ? 32 : 16) + 4*ENABLE_IRQ*ENABLE_IRQ_QREGS;
	localparam integer regindex_bits = (ENABLE_REGS_16_31 ? 5 : 4) + ENABLE_IRQ*ENABLE_IRQ_QREGS;

	localparam WITH_PCPI = ENABLE_PCPI || ENABLE_MUL;

	reg [63:0] count_cycle, count_instr;
	reg [31:0] reg_pc, reg_next_pc, reg_op1, reg_op2, reg_out;
	reg [31:0] cpuregs [0:regfile_size-1];
	reg [4:0] reg_sh;

	assign pcpi_rs1 = reg_op1;
	assign pcpi_rs2 = reg_op2;

	wire [31:0] next_pc;

	reg irq_active;
	reg [31:0] irq_mask;
	reg [31:0] irq_pending;
	reg [31:0] timer;


	// Internal PCPI Cores

	wire        pcpi_mul_wr;
	wire [31:0] pcpi_mul_rd;
	wire        pcpi_mul_wait;
	wire        pcpi_mul_ready;

	reg        pcpi_int_wr;
	reg [31:0] pcpi_int_rd;
	reg        pcpi_int_wait;
	reg        pcpi_int_ready;

	generate if (ENABLE_MUL) begin
		picorv32_pcpi_mul pcpi_mul (
			.clk       (clk            ),
			.resetn    (resetn         ),
			.pcpi_valid(pcpi_valid     ),
			.pcpi_insn (pcpi_insn      ),
			.pcpi_rs1  (pcpi_rs1       ),
			.pcpi_rs2  (pcpi_rs2       ),
			.pcpi_wr   (pcpi_mul_wr    ),
			.pcpi_rd   (pcpi_mul_rd    ),
			.pcpi_wait (pcpi_mul_wait  ),
			.pcpi_ready(pcpi_mul_ready )
		);
	end else begin
		assign pcpi_mul_wr = 0;
		assign pcpi_mul_rd = 1'bx;
		assign pcpi_mul_wait = 0;
		assign pcpi_mul_ready = 0;
	end endgenerate

	always @* begin
		pcpi_int_wr = 0;
		pcpi_int_rd = 1'bx;
		pcpi_int_wait  = |{ENABLE_PCPI && pcpi_wait,  ENABLE_MUL && pcpi_mul_wait};
		pcpi_int_ready = |{ENABLE_PCPI && pcpi_ready, ENABLE_MUL && pcpi_mul_ready};

		(* parallel_case *)
		case (1'b1)
			ENABLE_PCPI && pcpi_ready: begin
				pcpi_int_wr = pcpi_wr;
				pcpi_int_rd = pcpi_rd;
			end
			ENABLE_MUL && pcpi_mul_ready: begin
				pcpi_int_wr = pcpi_mul_wr;
				pcpi_int_rd = pcpi_mul_rd;
			end
		endcase
	end


	// Memory Interface

	reg [1:0] mem_state;
	reg [1:0] mem_wordsize;
	reg [31:0] mem_rdata_word;
	reg [31:0] mem_rdata_q;
	reg mem_do_prefetch;
	reg mem_do_rinst;
	reg mem_do_rdata;
	reg mem_do_wdata;

	wire mem_busy = |{mem_do_prefetch, mem_do_rinst, mem_do_rdata, mem_do_wdata};
	wire mem_done = (mem_ready && |mem_state && (mem_do_rinst || mem_do_rdata || mem_do_wdata)) || (&mem_state && mem_do_rinst);

	assign mem_la_write = resetn && !mem_state && mem_do_wdata;
	assign mem_la_read = resetn && !mem_state && (mem_do_rinst || mem_do_prefetch || mem_do_rdata);
	assign mem_la_addr = (mem_do_prefetch || mem_do_rinst) ? next_pc : {reg_op1[31:2], 2'b00};

	wire [31:0] mem_rdata_latched;
	assign mem_rdata_latched = ((mem_valid && mem_ready) || LATCHED_MEM_RDATA) ? mem_rdata : mem_rdata_q;

	always @* begin
		(* full_case *)
		case (mem_wordsize)
			0: begin
				mem_la_wdata = reg_op2;
				mem_la_wstrb = 4'b1111;
				mem_rdata_word = mem_rdata;
			end
			1: begin
				mem_la_wdata = {2{reg_op2[15:0]}};
				mem_la_wstrb = reg_op1[1] ? 4'b1100 : 4'b0011;
				case (reg_op1[1])
					1'b0: mem_rdata_word = mem_rdata[15: 0];
					1'b1: mem_rdata_word = mem_rdata[31:16];
				endcase
			end
			2: begin
				mem_la_wdata = {4{reg_op2[7:0]}};
				mem_la_wstrb = 4'b0001 << reg_op1[1:0];
				case (reg_op1[1:0])
					2'b00: mem_rdata_word = mem_rdata[ 7: 0];
					2'b01: mem_rdata_word = mem_rdata[15: 8];
					2'b10: mem_rdata_word = mem_rdata[23:16];
					2'b11: mem_rdata_word = mem_rdata[31:24];
				endcase
			end
		endcase
	end

	always @(posedge clk) begin
		if (mem_valid && mem_ready)
			mem_rdata_q <= mem_rdata_latched;
	end

	always @(posedge clk) begin
		if (!resetn) begin
			mem_state <= 0;
			mem_valid <= 0;
		end else case (mem_state)
			0: begin
				mem_addr <= mem_la_addr;
				mem_wdata <= mem_la_wdata;
				mem_wstrb <= mem_la_wstrb;
				if (mem_do_prefetch || mem_do_rinst || mem_do_rdata) begin
					mem_valid <= 1;
					mem_instr <= mem_do_prefetch || mem_do_rinst;
					mem_wstrb <= 0;
					mem_state <= 1;
				end
				if (mem_do_wdata) begin
					mem_valid <= 1;
					mem_instr <= 0;
					mem_state <= 2;
				end
			end
			1: begin
				if (mem_ready) begin
					mem_valid <= 0;
					mem_state <= mem_do_rinst || mem_do_rdata ? 0 : 3;
				end
			end
			2: begin
				if (mem_ready) begin
					mem_valid <= 0;
					mem_state <= 0;
				end
			end
			3: begin
				if (mem_do_rinst) begin
					mem_state <= 0;
				end
			end
		endcase
	end


	// Instruction Decoder

	reg instr_lui, instr_auipc, instr_jal, instr_jalr;
	reg instr_beq, instr_bne, instr_blt, instr_bge, instr_bltu, instr_bgeu;
	reg instr_lb, instr_lh, instr_lw, instr_lbu, instr_lhu, instr_sb, instr_sh, instr_sw;
	reg instr_addi, instr_slti, instr_sltiu, instr_xori, instr_ori, instr_andi, instr_slli, instr_srli, instr_srai;
	reg instr_add, instr_sub, instr_sll, instr_slt, instr_sltu, instr_xor, instr_srl, instr_sra, instr_or, instr_and;
	reg instr_rdcycle, instr_rdcycleh, instr_rdinstr, instr_rdinstrh;
	reg instr_getq, instr_setq, instr_retirq, instr_maskirq, instr_waitirq, instr_timer;
	wire instr_trap;

	reg [regindex_bits-1:0] decoded_rd, decoded_rs1, decoded_rs2;
	reg [31:0] decoded_imm, decoded_imm_uj;
	reg decoder_trigger;
	reg decoder_trigger_q;
	reg decoder_pseudo_trigger;

	reg is_lui_auipc_jal;
	reg is_lb_lh_lw_lbu_lhu;
	reg is_slli_srli_srai;
	reg is_jalr_addi_slti_sltiu_xori_ori_andi;
	reg is_sb_sh_sw;
	reg is_sll_srl_sra;
	reg is_lui_auipc_jal_jalr_addi_add;
	reg is_slti_blt_slt;
	reg is_sltiu_bltu_sltu;
	reg is_beq_bne_blt_bge_bltu_bgeu;
	reg is_lbu_lhu_lw;
	reg is_alu_reg_imm;
	reg is_alu_reg_reg;
	reg is_compare;

	assign instr_trap = (CATCH_ILLINSN || ENABLE_PCPI) && !{instr_lui, instr_auipc, instr_jal, instr_jalr,
			instr_beq, instr_bne, instr_blt, instr_bge, instr_bltu, instr_bgeu,
			instr_lb, instr_lh, instr_lw, instr_lbu, instr_lhu, instr_sb, instr_sh, instr_sw,
			instr_addi, instr_slti, instr_sltiu, instr_xori, instr_ori, instr_andi, instr_slli, instr_srli, instr_srai,
			instr_add, instr_sub, instr_sll, instr_slt, instr_sltu, instr_xor, instr_srl, instr_sra, instr_or, instr_and,
			instr_rdcycle, instr_rdcycleh, instr_rdinstr, instr_rdinstrh,
			instr_getq, instr_setq, instr_retirq, instr_maskirq, instr_waitirq, instr_timer};
	
	wire is_rdcycle_rdcycleh_rdinstr_rdinstrh;
	assign is_rdcycle_rdcycleh_rdinstr_rdinstrh = |{instr_rdcycle, instr_rdcycleh, instr_rdinstr, instr_rdinstrh};

	reg [63:0] new_instruction;
	reg [63:0] instruction;

	always @* begin
		new_instruction = "";
		if (instr_lui)      new_instruction = "lui";
		if (instr_auipc)    new_instruction = "auipc";
		if (instr_jal)      new_instruction = "jal";
		if (instr_jalr)     new_instruction = "jalr";

		if (instr_beq)      new_instruction = "beq";
		if (instr_bne)      new_instruction = "bne";
		if (instr_blt)      new_instruction = "blt";
		if (instr_bge)      new_instruction = "bge";
		if (instr_bltu)     new_instruction = "bltu";
		if (instr_bgeu)     new_instruction = "bgeu";

		if (instr_lb)       new_instruction = "lb";
		if (instr_lh)       new_instruction = "lh";
		if (instr_lw)       new_instruction = "lw";
		if (instr_lbu)      new_instruction = "lbu";
		if (instr_lhu)      new_instruction = "lhu";
		if (instr_sb)       new_instruction = "sb";
		if (instr_sh)       new_instruction = "sh";
		if (instr_sw)       new_instruction = "sw";

		if (instr_addi)     new_instruction = "addi";
		if (instr_slti)     new_instruction = "slti";
		if (instr_sltiu)    new_instruction = "sltiu";
		if (instr_xori)     new_instruction = "xori";
		if (instr_ori)      new_instruction = "ori";
		if (instr_andi)     new_instruction = "andi";
		if (instr_slli)     new_instruction = "slli";
		if (instr_srli)     new_instruction = "srli";
		if (instr_srai)     new_instruction = "srai";

		if (instr_add)      new_instruction = "add";
		if (instr_sub)      new_instruction = "sub";
		if (instr_sll)      new_instruction = "sll";
		if (instr_slt)      new_instruction = "slt";
		if (instr_sltu)     new_instruction = "sltu";
		if (instr_xor)      new_instruction = "xor";
		if (instr_srl)      new_instruction = "srl";
		if (instr_sra)      new_instruction = "sra";
		if (instr_or)       new_instruction = "or";
		if (instr_and)      new_instruction = "and";

		if (instr_rdcycle)  new_instruction = "rdcycle";
		if (instr_rdcycleh) new_instruction = "rdcycleh";
		if (instr_rdinstr)  new_instruction = "rdinstr";
		if (instr_rdinstrh) new_instruction = "rdinstrh";

		if (instr_getq)     new_instruction = "getq";
		if (instr_setq)     new_instruction = "setq";
		if (instr_retirq)   new_instruction = "retirq";
		if (instr_maskirq)  new_instruction = "maskirq";
		if (instr_waitirq)  new_instruction = "waitirq";
		if (instr_timer)    new_instruction = "timer";

		if (decoder_trigger_q)
			instruction = new_instruction;
	end

	always @(posedge clk) begin
		is_lui_auipc_jal <= |{instr_lui, instr_auipc, instr_jal};
		is_lui_auipc_jal_jalr_addi_add <= |{instr_lui, instr_auipc, instr_jal, instr_jalr, instr_addi, instr_add};
		is_slti_blt_slt <= |{instr_slti, instr_blt, instr_slt};
		is_sltiu_bltu_sltu <= |{instr_sltiu, instr_bltu, instr_sltu};
		is_lbu_lhu_lw <= |{instr_lbu, instr_lhu, instr_lw};
		is_compare <= |{is_beq_bne_blt_bge_bltu_bgeu, instr_slti, instr_slt, instr_sltiu, instr_sltu};

		if (mem_do_rinst && mem_done) begin
			instr_lui     <= mem_rdata_latched[6:0] == 7'b0110111;
			instr_auipc   <= mem_rdata_latched[6:0] == 7'b0010111;
			instr_jal     <= mem_rdata_latched[6:0] == 7'b1101111;
			instr_jalr    <= mem_rdata_latched[6:0] == 7'b1100111;
			instr_retirq  <= mem_rdata_latched[6:0] == 7'b0001011 && mem_rdata_latched[31:25] == 7'b0000010 && ENABLE_IRQ;
			instr_waitirq <= mem_rdata_latched[6:0] == 7'b0001011 && mem_rdata_latched[31:25] == 7'b0000100 && ENABLE_IRQ;

			is_beq_bne_blt_bge_bltu_bgeu <= mem_rdata_latched[6:0] == 7'b1100011;
			is_lb_lh_lw_lbu_lhu          <= mem_rdata_latched[6:0] == 7'b0000011;
			is_sb_sh_sw                  <= mem_rdata_latched[6:0] == 7'b0100011;
			is_alu_reg_imm               <= mem_rdata_latched[6:0] == 7'b0010011;
			is_alu_reg_reg               <= mem_rdata_latched[6:0] == 7'b0110011;

			{ 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_latched[31:12], 1'b0});

			decoded_rd <= mem_rdata_latched[11:7];
			decoded_rs1 <= mem_rdata_latched[19:15];
			decoded_rs2 <= mem_rdata_latched[24:20];

			if (mem_rdata_latched[6:0] == 7'b0001011 && mem_rdata_latched[31:25] == 7'b0000000 && ENABLE_IRQ && ENABLE_IRQ_QREGS)
				decoded_rs1[regindex_bits-1] <= 1; // instr_getq

			if (mem_rdata_latched[6:0] == 7'b0001011 && mem_rdata_latched[31:25] == 7'b0000010 && ENABLE_IRQ)
				decoded_rs1 <= ENABLE_IRQ_QREGS ? irqregs_offset : 3; // instr_retirq
		end

		if (decoder_trigger && !decoder_pseudo_trigger) begin
			if (WITH_PCPI) begin
				pcpi_insn <= mem_rdata_q;
			end

			instr_beq   <= is_beq_bne_blt_bge_bltu_bgeu && mem_rdata_q[14:12] == 3'b000;
			instr_bne   <= is_beq_bne_blt_bge_bltu_bgeu && mem_rdata_q[14:12] == 3'b001;
			instr_blt   <= is_beq_bne_blt_bge_bltu_bgeu && mem_rdata_q[14:12] == 3'b100;
			instr_bge   <= is_beq_bne_blt_bge_bltu_bgeu && mem_rdata_q[14:12] == 3'b101;
			instr_bltu  <= is_beq_bne_blt_bge_bltu_bgeu && mem_rdata_q[14:12] == 3'b110;
			instr_bgeu  <= is_beq_bne_blt_bge_bltu_bgeu && mem_rdata_q[14:12] == 3'b111;

			instr_lb    <= is_lb_lh_lw_lbu_lhu && mem_rdata_q[14:12] == 3'b000;
			instr_lh    <= is_lb_lh_lw_lbu_lhu && mem_rdata_q[14:12] == 3'b001;
			instr_lw    <= is_lb_lh_lw_lbu_lhu && mem_rdata_q[14:12] == 3'b010;
			instr_lbu   <= is_lb_lh_lw_lbu_lhu && mem_rdata_q[14:12] == 3'b100;
			instr_lhu   <= is_lb_lh_lw_lbu_lhu && mem_rdata_q[14:12] == 3'b101;

			instr_sb    <= is_sb_sh_sw && mem_rdata_q[14:12] == 3'b000;
			instr_sh    <= is_sb_sh_sw && mem_rdata_q[14:12] == 3'b001;
			instr_sw    <= is_sb_sh_sw && mem_rdata_q[14:12] == 3'b010;

			instr_addi  <= is_alu_reg_imm && mem_rdata_q[14:12] == 3'b000;
			instr_slti  <= is_alu_reg_imm && mem_rdata_q[14:12] == 3'b010;
			instr_sltiu <= is_alu_reg_imm && mem_rdata_q[14:12] == 3'b011;
			instr_xori  <= is_alu_reg_imm && mem_rdata_q[14:12] == 3'b100;
			instr_ori   <= is_alu_reg_imm && mem_rdata_q[14:12] == 3'b110;
			instr_andi  <= is_alu_reg_imm && mem_rdata_q[14:12] == 3'b111;

			instr_slli  <= is_alu_reg_imm && mem_rdata_q[14:12] == 3'b001 && mem_rdata_q[31:25] == 7'b0000000;
			instr_srli  <= is_alu_reg_imm && mem_rdata_q[14:12] == 3'b101 && mem_rdata_q[31:25] == 7'b0000000;
			instr_srai  <= is_alu_reg_imm && mem_rdata_q[14:12] == 3'b101 && mem_rdata_q[31:25] == 7'b0100000;

			instr_add   <= is_alu_reg_reg && mem_rdata_q[14:12] == 3'b000 && mem_rdata_q[31:25] == 7'b0000000;
			instr_sub   <= is_alu_reg_reg && mem_rdata_q[14:12] == 3'b000 && mem_rdata_q[31:25] == 7'b0100000;
			instr_sll   <= is_alu_reg_reg && mem_rdata_q[14:12] == 3'b001 && mem_rdata_q[31:25] == 7'b0000000;
			instr_slt   <= is_alu_reg_reg && mem_rdata_q[14:12] == 3'b010 && mem_rdata_q[31:25] == 7'b0000000;
			instr_sltu  <= is_alu_reg_reg && mem_rdata_q[14:12] == 3'b011 && mem_rdata_q[31:25] == 7'b0000000;
			instr_xor   <= is_alu_reg_reg && mem_rdata_q[14:12] == 3'b100 && mem_rdata_q[31:25] == 7'b0000000;
			instr_srl   <= is_alu_reg_reg && mem_rdata_q[14:12] == 3'b101 && mem_rdata_q[31:25] == 7'b0000000;
			instr_sra   <= is_alu_reg_reg && mem_rdata_q[14:12] == 3'b101 && mem_rdata_q[31:25] == 7'b0100000;
			instr_or    <= is_alu_reg_reg && mem_rdata_q[14:12] == 3'b110 && mem_rdata_q[31:25] == 7'b0000000;
			instr_and   <= is_alu_reg_reg && mem_rdata_q[14:12] == 3'b111 && mem_rdata_q[31:25] == 7'b0000000;

			instr_rdcycle  <= ((mem_rdata_q[6:0] == 7'b1110011 && mem_rdata_q[31:12] == 'b11000000000000000010) ||
			                   (mem_rdata_q[6:0] == 7'b1110011 && mem_rdata_q[31:12] == 'b11000000000100000010)) && ENABLE_COUNTERS;
			instr_rdcycleh <= ((mem_rdata_q[6:0] == 7'b1110011 && mem_rdata_q[31:12] == 'b11001000000000000010) ||
			                   (mem_rdata_q[6:0] == 7'b1110011 && mem_rdata_q[31:12] == 'b11001000000100000010)) && ENABLE_COUNTERS;
			instr_rdinstr  <=  (mem_rdata_q[6:0] == 7'b1110011 && mem_rdata_q[31:12] == 'b11000000001000000010) && ENABLE_COUNTERS;
			instr_rdinstrh <=  (mem_rdata_q[6:0] == 7'b1110011 && mem_rdata_q[31:12] == 'b11001000001000000010) && ENABLE_COUNTERS;

			instr_getq    <= mem_rdata_q[6:0] == 7'b0001011 && mem_rdata_q[31:25] == 7'b0000000 && ENABLE_IRQ && ENABLE_IRQ_QREGS;
			instr_setq    <= mem_rdata_q[6:0] == 7'b0001011 && mem_rdata_q[31:25] == 7'b0000001 && ENABLE_IRQ && ENABLE_IRQ_QREGS;
			instr_maskirq <= mem_rdata_q[6:0] == 7'b0001011 && mem_rdata_q[31:25] == 7'b0000011 && ENABLE_IRQ;
			instr_timer   <= mem_rdata_q[6:0] == 7'b0001011 && mem_rdata_q[31:25] == 7'b0000101 && ENABLE_IRQ && ENABLE_IRQ_TIMER;

			is_slli_srli_srai <= is_alu_reg_imm && |{
				mem_rdata_q[14:12] == 3'b001 && mem_rdata_q[31:25] == 7'b0000000,
				mem_rdata_q[14:12] == 3'b101 && mem_rdata_q[31:25] == 7'b0000000,
				mem_rdata_q[14:12] == 3'b101 && mem_rdata_q[31:25] == 7'b0100000
			};

			is_jalr_addi_slti_sltiu_xori_ori_andi <= instr_jalr || is_alu_reg_imm && |{
				mem_rdata_q[14:12] == 3'b000,
				mem_rdata_q[14:12] == 3'b010,
				mem_rdata_q[14:12] == 3'b011,
				mem_rdata_q[14:12] == 3'b100,
				mem_rdata_q[14:12] == 3'b110,
				mem_rdata_q[14:12] == 3'b111
			};

			is_sll_srl_sra <= is_alu_reg_reg && |{
				mem_rdata_q[14:12] == 3'b001 && mem_rdata_q[31:25] == 7'b0000000,
				mem_rdata_q[14:12] == 3'b101 && mem_rdata_q[31:25] == 7'b0000000,
				mem_rdata_q[14:12] == 3'b101 && mem_rdata_q[31:25] == 7'b0100000
			};

			(* parallel_case *)
			case (1'b1)
				instr_jal:
					decoded_imm <= decoded_imm_uj;
				|{instr_lui, instr_auipc}:
					decoded_imm <= mem_rdata_q[31:12] << 12;
				|{instr_jalr, is_lb_lh_lw_lbu_lhu, is_alu_reg_imm}:
					decoded_imm <= $signed(mem_rdata_q[31:20]);
				is_beq_bne_blt_bge_bltu_bgeu:
					decoded_imm <= $signed({mem_rdata_q[31], mem_rdata_q[7], mem_rdata_q[30:25], mem_rdata_q[11:8], 1'b0});
				is_sb_sh_sw:
					decoded_imm <= $signed({mem_rdata_q[31:25], mem_rdata_q[11:7]});
				default:
					decoded_imm <= 1'bx;
			endcase
		end
	end


	// Main State Machine

	localparam cpu_state_trap   = 8'b10000000;
	localparam cpu_state_fetch  = 8'b01000000;
	localparam cpu_state_ld_rs1 = 8'b00100000;
	localparam cpu_state_ld_rs2 = 8'b00010000;
	localparam cpu_state_exec   = 8'b00001000;
	localparam cpu_state_shift  = 8'b00000100;
	localparam cpu_state_stmem  = 8'b00000010;
	localparam cpu_state_ldmem  = 8'b00000001;

	reg [7:0] cpu_state;
	reg [1:0] irq_state;

	reg set_mem_do_rinst;
	reg set_mem_do_rdata;
	reg set_mem_do_wdata;

	reg latched_store;
	reg latched_stalu;
	reg latched_branch;
	reg latched_is_lu;
	reg latched_is_lh;
	reg latched_is_lb;
	reg [regindex_bits-1:0] latched_rd;

	reg [31:0] current_pc;
	assign next_pc = latched_store && latched_branch ? reg_out : reg_next_pc;

	reg [3:0] pcpi_timeout_counter;
	reg pcpi_timeout;

	reg [31:0] next_irq_pending;
	reg do_waitirq;

	reg [31:0] alu_out, reg_alu_out;
	reg alu_out_0, reg_alu_out_0;
	reg alu_wait;

	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;
			is_compare:
				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;

		reg_alu_out <= alu_out;
		reg_alu_out_0 <= alu_out_0;
		alu_wait <= 0;

		if (WITH_PCPI && CATCH_ILLINSN) begin
			if (resetn && pcpi_valid && !pcpi_int_wait) begin
				if (pcpi_timeout_counter)
					pcpi_timeout_counter <= pcpi_timeout_counter - 1;
			end else
				pcpi_timeout_counter <= ~0;
			pcpi_timeout <= !pcpi_timeout_counter;
		end

		if (ENABLE_COUNTERS)
			count_cycle <= resetn ? count_cycle + 1 : 0;

		next_irq_pending = ENABLE_IRQ ? irq_pending & LATCHED_IRQ : 'bx;

		if (ENABLE_IRQ && ENABLE_IRQ_TIMER && timer) begin
			if (timer - 1 == 0)
				next_irq_pending[irq_timer] = 1;
			timer <= timer - 1;
		end

		if (ENABLE_IRQ) begin
			next_irq_pending = next_irq_pending | irq;
		end

		decoder_trigger_q <= decoder_trigger;
		decoder_trigger <= mem_do_rinst && mem_done;
		decoder_pseudo_trigger <= 0;
		do_waitirq <= 0;

		if (!resetn) begin
			reg_pc <= PROGADDR_RESET;
			reg_next_pc <= PROGADDR_RESET;
			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;
			pcpi_valid <= 0;
			irq_active <= 0;
			irq_mask <= ~0;
			next_irq_pending = 0;
			irq_state <= 0;
			eoi <= 0;
			timer <= 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 && !do_waitirq;
				mem_wordsize <= 0;

				current_pc = reg_next_pc;

				(* parallel_case *)
				case (1'b1)
					latched_branch: begin
						current_pc = latched_store ? (latched_stalu ? reg_alu_out : reg_out) : reg_next_pc;
						`debug($display("ST_RD:  %2d 0x%08x, BRANCH 0x%08x", latched_rd, reg_pc + 4, current_pc);)
						cpuregs[latched_rd] <= reg_pc + 4;
					end
					latched_store && !latched_branch: begin
						`debug($display("ST_RD:  %2d 0x%08x", latched_rd, latched_stalu ? reg_alu_out : reg_out);)
						cpuregs[latched_rd] <= latched_stalu ? reg_alu_out : reg_out;
					end
					ENABLE_IRQ && irq_state[0]: begin
						cpuregs[latched_rd] <= current_pc;
						current_pc = PROGADDR_IRQ;
						irq_active <= 1;
						mem_do_rinst <= 1;
					end
					ENABLE_IRQ && irq_state[1]: begin
						eoi <= irq_pending & ~irq_mask;
						cpuregs[latched_rd] <= irq_pending & ~irq_mask;
						next_irq_pending = next_irq_pending & irq_mask;
					end
				endcase

				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 (ENABLE_IRQ && ((decoder_trigger && !irq_active && |(irq_pending & ~irq_mask)) || irq_state)) begin
					irq_state <=
						irq_state == 2'b00 ? 2'b01 :
						irq_state == 2'b01 ? 2'b10 : 2'b00;
					if (ENABLE_IRQ_QREGS)
						latched_rd <= irqregs_offset | irq_state[0];
					else
						latched_rd <= irq_state[0] ? 4 : 3;
				end else
				if (ENABLE_IRQ && (decoder_trigger || do_waitirq) && instr_waitirq) begin
					if (irq_pending) begin
						latched_store <= 1;
						reg_out <= irq_pending;
						reg_next_pc <= current_pc + 4;
						mem_do_rinst <= 1;
					end else
						do_waitirq <= 1;
				end else
				if (decoder_trigger) begin
					`debug($display("-- %-0t", $time);)
					reg_next_pc <= current_pc + 4;
					if (ENABLE_COUNTERS)
						count_instr <= count_instr + 1;
					if (instr_jal) begin
						`debug($display("DECODE: 0x%08x jal", current_pc);)
						mem_do_rinst <= 1;
						reg_next_pc <= current_pc + decoded_imm_uj;
						latched_branch <= 1;
					end else begin
						mem_do_rinst <= 0;
						mem_do_prefetch <= !instr_jalr && !instr_retirq;
						cpu_state <= cpu_state_ld_rs1;
					end
				end
			end

			cpu_state_ld_rs1: begin
				reg_op1 <= 'bx;
				reg_op2 <= 'bx;
				`debug($display("DECODE: 0x%08x %-0s", reg_pc, instruction ? instruction : "UNKNOWN");)

				(* parallel_case *)
				case (1'b1)
					(CATCH_ILLINSN || WITH_PCPI) && instr_trap: begin
						if (WITH_PCPI) begin
							`debug($display("LD_RS1: %2d 0x%08x", decoded_rs1, decoded_rs1 ? cpuregs[decoded_rs1] : 0);)
							reg_op1 <= decoded_rs1 ? cpuregs[decoded_rs1] : 0;
							if (ENABLE_REGS_DUALPORT) begin
								pcpi_valid <= 1;
								`debug($display("LD_RS2: %2d 0x%08x", decoded_rs2, decoded_rs2 ? cpuregs[decoded_rs2] : 0);)
								reg_sh <= decoded_rs2 ? cpuregs[decoded_rs2] : 0;
								reg_op2 <= decoded_rs2 ? cpuregs[decoded_rs2] : 0;
								if (pcpi_int_ready) begin
									mem_do_rinst <= 1;
									pcpi_valid <= 0;
									reg_out <= pcpi_int_rd;
									latched_store <= pcpi_int_wr;
									cpu_state <= cpu_state_fetch;
								end else
								if (CATCH_ILLINSN && pcpi_timeout) begin
									`debug($display("SBREAK OR UNSUPPORTED INSN AT 0x%08x", reg_pc);)
									if (ENABLE_IRQ && !irq_mask[irq_sbreak] && !irq_active) begin
										next_irq_pending[irq_sbreak] = 1;
										cpu_state <= cpu_state_fetch;
									end else
										cpu_state <= cpu_state_trap;
								end
							end else begin
								cpu_state <= cpu_state_ld_rs2;
							end
						end else begin
							`debug($display("SBREAK OR UNSUPPORTED INSN AT 0x%08x", reg_pc);)
							if (ENABLE_IRQ && !irq_mask[irq_sbreak] && !irq_active) begin
								next_irq_pending[irq_sbreak] = 1;
								cpu_state <= cpu_state_fetch;
							end else
								cpu_state <= cpu_state_trap;
						end
					end
					ENABLE_COUNTERS && is_rdcycle_rdcycleh_rdinstr_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;
						cpu_state <= cpu_state_fetch;
					end
					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
					ENABLE_IRQ && ENABLE_IRQ_QREGS && instr_getq: begin
						`debug($display("LD_RS1: %2d 0x%08x", decoded_rs1, decoded_rs1 ? cpuregs[decoded_rs1] : 0);)
						reg_out <= decoded_rs1 ? cpuregs[decoded_rs1] : 0;
						latched_store <= 1;
						cpu_state <= cpu_state_fetch;
					end
					ENABLE_IRQ && ENABLE_IRQ_QREGS && instr_setq: begin
						`debug($display("LD_RS1: %2d 0x%08x", decoded_rs1, decoded_rs1 ? cpuregs[decoded_rs1] : 0);)
						reg_out <= decoded_rs1 ? cpuregs[decoded_rs1] : 0;
						latched_rd <= latched_rd | irqregs_offset;
						latched_store <= 1;
						cpu_state <= cpu_state_fetch;
					end
					ENABLE_IRQ && instr_retirq: begin
						eoi <= 0;
						irq_active <= 0;
						latched_branch <= 1;
						latched_store <= 1;
						`debug($display("LD_RS1: %2d 0x%08x", decoded_rs1, decoded_rs1 ? cpuregs[decoded_rs1] : 0);)
						reg_out <= decoded_rs1 ? cpuregs[decoded_rs1] : 0;
						cpu_state <= cpu_state_fetch;
					end
					ENABLE_IRQ && instr_maskirq: begin
						latched_store <= 1;
						reg_out <= irq_mask;
						`debug($display("LD_RS1: %2d 0x%08x", decoded_rs1, decoded_rs1 ? cpuregs[decoded_rs1] : 0);)
						irq_mask <= (decoded_rs1 ? cpuregs[decoded_rs1] : 0) | MASKED_IRQ;
						cpu_state <= cpu_state_fetch;
					end
					ENABLE_IRQ && ENABLE_IRQ_TIMER && instr_timer: begin
						latched_store <= 1;
						reg_out <= timer;
						`debug($display("LD_RS1: %2d 0x%08x", decoded_rs1, decoded_rs1 ? cpuregs[decoded_rs1] : 0);)
						timer <= decoded_rs1 ? cpuregs[decoded_rs1] : 0;
						cpu_state <= cpu_state_fetch;
					end
					is_lb_lh_lw_lbu_lhu: begin
						`debug($display("LD_RS1: %2d 0x%08x", decoded_rs1, decoded_rs1 ? cpuregs[decoded_rs1] : 0);)
						reg_op1 <= decoded_rs1 ? cpuregs[decoded_rs1] : 0;
						cpu_state <= cpu_state_ldmem;
						mem_do_rinst <= 1;
					end
					is_slli_srli_srai: begin
						`debug($display("LD_RS1: %2d 0x%08x", decoded_rs1, decoded_rs1 ? cpuregs[decoded_rs1] : 0);)
						reg_op1 <= decoded_rs1 ? cpuregs[decoded_rs1] : 0;
						reg_sh <= decoded_rs2;
						cpu_state <= cpu_state_shift;
					end
					is_jalr_addi_slti_sltiu_xori_ori_andi: begin
						`debug($display("LD_RS1: %2d 0x%08x", decoded_rs1, decoded_rs1 ? cpuregs[decoded_rs1] : 0);)
						reg_op1 <= decoded_rs1 ? cpuregs[decoded_rs1] : 0;
						reg_op2 <= decoded_imm;
						mem_do_rinst <= mem_do_prefetch;
						cpu_state <= cpu_state_exec;
					end
					default: begin
						`debug($display("LD_RS1: %2d 0x%08x", decoded_rs1, decoded_rs1 ? cpuregs[decoded_rs1] : 0);)
						reg_op1 <= decoded_rs1 ? cpuregs[decoded_rs1] : 0;
						if (ENABLE_REGS_DUALPORT) begin
							`debug($display("LD_RS2: %2d 0x%08x", decoded_rs2, decoded_rs2 ? cpuregs[decoded_rs2] : 0);)
							reg_sh <= decoded_rs2 ? cpuregs[decoded_rs2] : 0;
							reg_op2 <= decoded_rs2 ? cpuregs[decoded_rs2] : 0;
							(* parallel_case *)
							case (1'b1)
								is_sb_sh_sw: begin
									cpu_state <= cpu_state_stmem;
									mem_do_rinst <= 1;
								end
								is_sll_srl_sra: begin
									cpu_state <= cpu_state_shift;
								end
								default: begin
									if (TWO_CYCLE_COMPARE && is_beq_bne_blt_bge_bltu_bgeu)
										alu_wait <= 1;
									else
										mem_do_rinst <= mem_do_prefetch;
									cpu_state <= cpu_state_exec;
								end
							endcase
						end else
							cpu_state <= cpu_state_ld_rs2;
					end
				endcase
			end

			cpu_state_ld_rs2: begin
				`debug($display("LD_RS2: %2d 0x%08x", decoded_rs2, decoded_rs2 ? cpuregs[decoded_rs2] : 0);)
				reg_sh <= decoded_rs2 ? cpuregs[decoded_rs2] : 0;
				reg_op2 <= decoded_rs2 ? cpuregs[decoded_rs2] : 0;

				(* parallel_case *)
				case (1'b1)
					WITH_PCPI && instr_trap: begin
						pcpi_valid <= 1;
						if (pcpi_int_ready) begin
							mem_do_rinst <= 1;
							pcpi_valid <= 0;
							reg_out <= pcpi_int_rd;
							latched_store <= pcpi_int_wr;
							cpu_state <= cpu_state_fetch;
						end else
						if (CATCH_ILLINSN && pcpi_timeout) begin
							`debug($display("SBREAK OR UNSUPPORTED INSN AT 0x%08x", reg_pc);)
							if (ENABLE_IRQ && !irq_mask[irq_sbreak] && !irq_active) begin
								next_irq_pending[irq_sbreak] = 1;
								cpu_state <= cpu_state_fetch;
							end else
								cpu_state <= cpu_state_trap;
						end
					end
					is_sb_sh_sw: begin
						cpu_state <= cpu_state_stmem;
						mem_do_rinst <= 1;
					end
					is_sll_srl_sra: begin
						cpu_state <= cpu_state_shift;
					end
					default: begin
						if (TWO_CYCLE_COMPARE && is_beq_bne_blt_bge_bltu_bgeu)
							alu_wait <= 1;
						else
							mem_do_rinst <= mem_do_prefetch;
						cpu_state <= cpu_state_exec;
					end
				endcase
			end

			cpu_state_exec: begin
				latched_store <= TWO_CYCLE_COMPARE ? reg_alu_out_0 : alu_out_0;
				latched_branch <= TWO_CYCLE_COMPARE ? reg_alu_out_0 : alu_out_0;
				reg_out <= reg_pc + decoded_imm;
				if (TWO_CYCLE_COMPARE && alu_wait) begin
					mem_do_rinst <= mem_do_prefetch;
				end else
				if (is_beq_bne_blt_bge_bltu_bgeu) begin
					latched_rd <= 0;
					if (mem_done)
						cpu_state <= cpu_state_fetch;
					if (TWO_CYCLE_COMPARE ? reg_alu_out_0 : alu_out_0) begin
						decoder_trigger <= 0;
						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
				latched_store <= 1;
				if (reg_sh == 0) begin
					reg_out <= reg_op1;
					mem_do_rinst <= mem_do_prefetch;
					cpu_state <= cpu_state_fetch;
				end else if (TWO_STAGE_SHIFT && 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;
						decoder_trigger <= 1;
						decoder_pseudo_trigger <= 1;
					end
				end
			end

			cpu_state_ldmem: begin
				latched_store <= 1;
				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_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_rdata_word;
							latched_is_lh: reg_out <= $signed(mem_rdata_word[15:0]);
							latched_is_lb: reg_out <= $signed(mem_rdata_word[7:0]);
						endcase
						decoder_trigger <= 1;
						decoder_pseudo_trigger <= 1;
						cpu_state <= cpu_state_fetch;
					end
				end
			end
		endcase

		if (CATCH_MISALIGN && resetn && (mem_do_rdata || mem_do_wdata)) begin
			if (mem_wordsize == 0 && reg_op1[1:0] != 0) begin
				`debug($display("MISALIGNED WORD: 0x%08x", reg_op1);)
				if (ENABLE_IRQ && !irq_mask[irq_buserror] && !irq_active) begin
					next_irq_pending[irq_buserror] = 1;
				end else
					cpu_state <= cpu_state_trap;
			end
			if (mem_wordsize == 1 && reg_op1[0] != 0) begin
				`debug($display("MISALIGNED HALFWORD: 0x%08x", reg_op1);)
				if (ENABLE_IRQ && !irq_mask[irq_buserror] && !irq_active) begin
					next_irq_pending[irq_buserror] = 1;
				end else
					cpu_state <= cpu_state_trap;
			end
		end
		if (CATCH_MISALIGN && resetn && mem_do_rinst && reg_pc[1:0] != 0) begin
			`debug($display("MISALIGNED INSTRUCTION: 0x%08x", reg_pc);)
			if (ENABLE_IRQ && !irq_mask[irq_buserror] && !irq_active) begin
				next_irq_pending[irq_buserror] = 1;
			end else
				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;

		irq_pending <= next_irq_pending & ~MASKED_IRQ;

		reg_pc[1:0] <= 0;
		reg_next_pc[1:0] <= 0;
		current_pc = 'bx;
	end
endmodule


/***************************************************************
 * picorv32_pcpi_mul
 ***************************************************************/

module picorv32_pcpi_mul #(
	parameter STEPS_AT_ONCE = 1,
	parameter CARRY_CHAIN = 4
) (
	input clk, resetn,

	input             pcpi_valid,
	input      [31:0] pcpi_insn,
	input      [31:0] pcpi_rs1,
	input      [31:0] pcpi_rs2,
	output reg        pcpi_wr,
	output reg [31:0] pcpi_rd,
	output reg        pcpi_wait,
	output reg        pcpi_ready
);
	reg instr_mul, instr_mulh, instr_mulhsu, instr_mulhu;
	wire instr_any_mul = |{instr_mul, instr_mulh, instr_mulhsu, instr_mulhu};
	wire instr_any_mulh = |{instr_mulh, instr_mulhsu, instr_mulhu};
	wire instr_rs1_signed = |{instr_mulh, instr_mulhsu};
	wire instr_rs2_signed = |{instr_mulh};

	reg pcpi_wait_q;
	wire mul_start = pcpi_wait && !pcpi_wait_q;

	always @(posedge clk) begin
		instr_mul <= 0;
		instr_mulh <= 0;
		instr_mulhsu <= 0;
		instr_mulhu <= 0;

		if (resetn && pcpi_valid && pcpi_insn[6:0] == 7'b0110011 && pcpi_insn[31:25] == 7'b0000001) begin
			case (pcpi_insn[14:12])
				3'b000: instr_mul <= 1;
				3'b001: instr_mulh <= 1;
				3'b010: instr_mulhsu <= 1;
				3'b011: instr_mulhu <= 1;
			endcase
		end

		pcpi_wait <= instr_any_mul;
		pcpi_wait_q <= pcpi_wait;
	end

	reg [63:0] rs1, rs2, rd, rdx;
	reg [63:0] next_rs1, next_rs2, this_rs2;
	reg [63:0] next_rd, next_rdx, next_rdt;
	reg [6:0] mul_counter;
	reg mul_waiting;
	reg mul_finish;
	integer i, j;

	// carry save accumulator
	always @* begin
		next_rd = rd;
		next_rdx = rdx;
		next_rs1 = rs1;
		next_rs2 = rs2;

		for (i = 0; i < STEPS_AT_ONCE; i=i+1) begin
			this_rs2 = next_rs1[0] ? next_rs2 : 0;
			if (CARRY_CHAIN == 0) begin
				next_rdt = next_rd ^ next_rdx ^ this_rs2;
				next_rdx = ((next_rd & next_rdx) | (next_rd & this_rs2) | (next_rdx & this_rs2)) << 1;
				next_rd = next_rdt;
			end else begin
				next_rdt = 0;
				for (j = 0; j < 64; j = j + CARRY_CHAIN)
					{next_rdt[j+CARRY_CHAIN-1], next_rd[j +: CARRY_CHAIN]} =
							next_rd[j +: CARRY_CHAIN] + next_rdx[j +: CARRY_CHAIN] + this_rs2[j +: CARRY_CHAIN];
				next_rdx = next_rdt << 1;
			end
			next_rs1 = next_rs1 >> 1;
			next_rs2 = next_rs2 << 1;
		end
	end

	always @(posedge clk) begin
		mul_finish <= 0;
		if (!resetn) begin
			mul_waiting <= 1;
		end else
		if (mul_waiting) begin
			if (instr_rs1_signed)
				rs1 <= $signed(pcpi_rs1);
			else
				rs1 <= $unsigned(pcpi_rs1);

			if (instr_rs2_signed)
				rs2 <= $signed(pcpi_rs2);
			else
				rs2 <= $unsigned(pcpi_rs2);

			rd <= 0;
			rdx <= 0;
			mul_counter <= (instr_any_mulh ? 63 - STEPS_AT_ONCE : 31 - STEPS_AT_ONCE);
			mul_waiting <= !mul_start;
		end else begin
			rd <= next_rd;
			rdx <= next_rdx;
			rs1 <= next_rs1;
			rs2 <= next_rs2;

			mul_counter <= mul_counter - STEPS_AT_ONCE;
			if (mul_counter[6]) begin
				mul_finish <= 1;
				mul_waiting <= 1;
			end
		end
	end

	always @(posedge clk) begin
		pcpi_wr <= 0;
		pcpi_ready <= 0;
		if (mul_finish) begin
			pcpi_wr <= 1;
			pcpi_ready <= 1;
			pcpi_rd <= instr_any_mulh ? rd >> 32 : rd;
		end
	end
endmodule


/***************************************************************
 * picorv32_axi
 ***************************************************************/

module picorv32_axi #(
	parameter [ 0:0] ENABLE_COUNTERS = 1,
	parameter [ 0:0] ENABLE_REGS_16_31 = 1,
	parameter [ 0:0] ENABLE_REGS_DUALPORT = 1,
	parameter [ 0:0] TWO_STAGE_SHIFT = 1,
	parameter [ 0:0] TWO_CYCLE_COMPARE = 0,
	parameter [ 0:0] CATCH_MISALIGN = 1,
	parameter [ 0:0] CATCH_ILLINSN = 1,
	parameter [ 0:0] ENABLE_PCPI = 0,
	parameter [ 0:0] ENABLE_MUL = 0,
	parameter [ 0:0] ENABLE_IRQ = 0,
	parameter [ 0:0] ENABLE_IRQ_QREGS = 1,
	parameter [ 0:0] ENABLE_IRQ_TIMER = 1,
	parameter [31:0] MASKED_IRQ = 32'h 0000_0000,
	parameter [31:0] LATCHED_IRQ = 32'h ffff_ffff,
	parameter [31:0] PROGADDR_RESET = 32'h 0000_0000,
	parameter [31:0] PROGADDR_IRQ = 32'h 0000_0010
) (
	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,

	// Pico Co-Processor Interface (PCPI)
	output        pcpi_valid,
	output [31:0] pcpi_insn,
	output [31:0] pcpi_rs1,
	output [31:0] pcpi_rs2,
	input         pcpi_wr,
	input  [31:0] pcpi_rd,
	input         pcpi_wait,
	input         pcpi_ready,

	// IRQ interface
	input  [31:0] irq,
	output [31:0] eoi
);
	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   ),
		.ENABLE_REGS_DUALPORT(ENABLE_REGS_DUALPORT),
		.TWO_STAGE_SHIFT     (TWO_STAGE_SHIFT     ),
		.TWO_CYCLE_COMPARE   (TWO_CYCLE_COMPARE   ),
		.CATCH_MISALIGN      (CATCH_MISALIGN      ),
		.CATCH_ILLINSN       (CATCH_ILLINSN       ),
		.ENABLE_PCPI         (ENABLE_PCPI         ),
		.ENABLE_MUL          (ENABLE_MUL          ),
		.ENABLE_IRQ          (ENABLE_IRQ          ),
		.ENABLE_IRQ_QREGS    (ENABLE_IRQ_QREGS    ),
		.ENABLE_IRQ_TIMER    (ENABLE_IRQ_TIMER    ),
		.MASKED_IRQ          (MASKED_IRQ          ),
		.LATCHED_IRQ         (LATCHED_IRQ         ),
		.PROGADDR_RESET      (PROGADDR_RESET      ),
		.PROGADDR_IRQ        (PROGADDR_IRQ        )
	) 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),

		.pcpi_valid(pcpi_valid),
		.pcpi_insn (pcpi_insn ),
		.pcpi_rs1  (pcpi_rs1  ),
		.pcpi_rs2  (pcpi_rs2  ),
		.pcpi_wr   (pcpi_wr   ),
		.pcpi_rd   (pcpi_rd   ),
		.pcpi_wait (pcpi_wait ),
		.pcpi_ready(pcpi_ready),

		.irq(irq),
		.eoi(eoi)
	);
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;

	always @(posedge clk) begin
		if (!resetn) begin
			ack_awvalid <= 0;
		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