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// 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. //
// //
////////////////////////////////////////////////////////////////////////////////
// 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_compressed_decoder (
instr_i,
instr_o,
is_compressed_o,
illegal_instr_o
);
input wire [31:0] instr_i;
output reg [31:0] instr_o;
output wire is_compressed_o;
output reg illegal_instr_o;
localparam [6:0] ibex_defines_OPCODE_BRANCH = 7'h63;
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;
always @(*) begin
illegal_instr_o = 1'b0;
instr_o = {32 {1'sb0}};
case (instr_i[1:0])
2'b00:
case (instr_i[15:13])
3'b000: begin
instr_o = {2'b00, instr_i[10:7], instr_i[12:11], instr_i[5], instr_i[6], 2'b00, 5'h02, 3'b000, 2'b01, instr_i[4:2], {ibex_defines_OPCODE_OPIMM}};
if (instr_i[12:5] == 8'b00000000)
illegal_instr_o = 1'b1;
end
3'b010: instr_o = {5'b00000, instr_i[5], instr_i[12:10], instr_i[6], 2'b00, 2'b01, instr_i[9:7], 3'b010, 2'b01, instr_i[4:2], {ibex_defines_OPCODE_LOAD}};
3'b110: instr_o = {5'b00000, instr_i[5], instr_i[12], 2'b01, instr_i[4:2], 2'b01, instr_i[9:7], 3'b010, instr_i[11:10], instr_i[6], 2'b00, {ibex_defines_OPCODE_STORE}};
default: illegal_instr_o = 1'b1;
endcase
2'b01:
case (instr_i[15:13])
3'b000: instr_o = {{6 {instr_i[12]}}, instr_i[12], instr_i[6:2], instr_i[11:7], 3'b000, instr_i[11:7], {ibex_defines_OPCODE_OPIMM}};
3'b001, 3'b101: instr_o = {instr_i[12], instr_i[8], instr_i[10:9], instr_i[6], instr_i[7], instr_i[2], instr_i[11], instr_i[5:3], {9 {instr_i[12]}}, 4'b0000, ~instr_i[15], {ibex_defines_OPCODE_JAL}};
3'b010: begin
instr_o = {{6 {instr_i[12]}}, instr_i[12], instr_i[6:2], 5'b00000, 3'b000, instr_i[11:7], {ibex_defines_OPCODE_OPIMM}};
if (instr_i[11:7] == 5'b00000)
illegal_instr_o = 1'b1;
end
3'b011: begin
instr_o = {{15 {instr_i[12]}}, instr_i[6:2], instr_i[11:7], {ibex_defines_OPCODE_LUI}};
if (instr_i[11:7] == 5'h02)
instr_o = {{3 {instr_i[12]}}, instr_i[4:3], instr_i[5], instr_i[2], instr_i[6], 4'b0000, 5'h02, 3'b000, 5'h02, {ibex_defines_OPCODE_OPIMM}};
else if (instr_i[11:7] == 5'b00000)
illegal_instr_o = 1'b1;
if ({instr_i[12], instr_i[6:2]} == 6'b000000)
illegal_instr_o = 1'b1;
end
3'b100:
case (instr_i[11:10])
2'b00, 2'b01: begin
instr_o = {1'b0, instr_i[10], 5'b00000, instr_i[6:2], 2'b01, instr_i[9:7], 3'b101, 2'b01, instr_i[9:7], {ibex_defines_OPCODE_OPIMM}};
if (instr_i[12] == 1'b1)
illegal_instr_o = 1'b1;
if (instr_i[6:2] == 5'b00000)
illegal_instr_o = 1'b1;
end
2'b10: instr_o = {{6 {instr_i[12]}}, instr_i[12], instr_i[6:2], 2'b01, instr_i[9:7], 3'b111, 2'b01, instr_i[9:7], {ibex_defines_OPCODE_OPIMM}};
2'b11:
case ({instr_i[12], instr_i[6:5]})
3'b000: instr_o = {9'b010000001, instr_i[4:2], 2'b01, instr_i[9:7], 3'b000, 2'b01, instr_i[9:7], {ibex_defines_OPCODE_OP}};
3'b001: instr_o = {9'b000000001, instr_i[4:2], 2'b01, instr_i[9:7], 3'b100, 2'b01, instr_i[9:7], {ibex_defines_OPCODE_OP}};
3'b010: instr_o = {9'b000000001, instr_i[4:2], 2'b01, instr_i[9:7], 3'b110, 2'b01, instr_i[9:7], {ibex_defines_OPCODE_OP}};
3'b011: instr_o = {9'b000000001, instr_i[4:2], 2'b01, instr_i[9:7], 3'b111, 2'b01, instr_i[9:7], {ibex_defines_OPCODE_OP}};
3'b100, 3'b101, 3'b110, 3'b111: illegal_instr_o = 1'b1;
endcase
endcase
3'b110, 3'b111: instr_o = {{4 {instr_i[12]}}, instr_i[6:5], instr_i[2], 5'b00000, 2'b01, instr_i[9:7], 2'b00, instr_i[13], instr_i[11:10], instr_i[4:3], instr_i[12], {ibex_defines_OPCODE_BRANCH}};
default:
;
endcase
2'b10:
case (instr_i[15:13])
3'b000: begin
instr_o = {7'b0000000, instr_i[6:2], instr_i[11:7], 3'b001, instr_i[11:7], {ibex_defines_OPCODE_OPIMM}};
if (instr_i[11:7] == 5'b00000)
illegal_instr_o = 1'b1;
if ((instr_i[12] == 1'b1) || (instr_i[6:2] == 5'b00000))
illegal_instr_o = 1'b1;
end
3'b010: begin
instr_o = {4'b0000, instr_i[3:2], instr_i[12], instr_i[6:4], 2'b00, 5'h02, 3'b010, instr_i[11:7], ibex_defines_OPCODE_LOAD};
if (instr_i[11:7] == 5'b00000)
illegal_instr_o = 1'b1;
end
3'b100:
if (instr_i[12] == 1'b0) begin
instr_o = {7'b0000000, instr_i[6:2], 5'b00000, 3'b000, instr_i[11:7], {ibex_defines_OPCODE_OP}};
if (instr_i[6:2] == 5'b00000)
instr_o = {12'b000000000000, instr_i[11:7], 3'b000, 5'b00000, {ibex_defines_OPCODE_JALR}};
end
else begin
instr_o = {7'b0000000, instr_i[6:2], instr_i[11:7], 3'b000, instr_i[11:7], {ibex_defines_OPCODE_OP}};
if (instr_i[11:7] == 5'b00000) begin
instr_o = 32'h00100073;
if (instr_i[6:2] != 5'b00000)
illegal_instr_o = 1'b1;
end
else if (instr_i[6:2] == 5'b00000)
instr_o = {12'b000000000000, instr_i[11:7], 3'b000, 5'b00001, {ibex_defines_OPCODE_JALR}};
end
3'b110: instr_o = {4'b0000, instr_i[8:7], instr_i[12], instr_i[6:2], 5'h02, 3'b010, instr_i[11:9], 2'b00, {ibex_defines_OPCODE_STORE}};
default: illegal_instr_o = 1'b1;
endcase
default: instr_o = instr_i;
endcase
end
assign is_compressed_o = instr_i[1:0] != 2'b11;
endmodule