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Fix/Update compressed decoder for newest RVC 1.8 draft

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Sven Stucki 2015-10-18 19:28:41 +02:00
parent 7d06e4ab62
commit 26394abcaf
1 changed files with 32 additions and 50 deletions
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82
compressed_decoder.sv
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@ -53,6 +53,7 @@ module compressed_decoder
3'b000: begin
// c.addi4spn -> addi rd', x2, imm
instr_o = {2'b0, 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], `OPCODE_OPIMM};
if (instr_i[12:5] == 8'b0) illegal_instr_o = 1'b1;
end
3'b010: begin
@ -99,6 +100,8 @@ module compressed_decoder
if (instr_i[11:7] == 5'h02) begin
// c.addi16sp -> addi x2, x2, nzimm
instr_o = {{3 {instr_i[12]}}, instr_i[4:3], instr_i[5], instr_i[2], instr_i[6], 4'b0, 5'h02, 3'b000, 5'h02, `OPCODE_OPIMM};
end else if (instr_i[11:7] == 5'b0) begin
illegal_instr_o = 1'b1;
end
if ({instr_i[12], instr_i[6:2]} == 6'b0) illegal_instr_o = 1'b1;
@ -106,67 +109,46 @@ module compressed_decoder
3'b100: begin
unique case (instr_i[11:10])
2'b00: begin
// c.srli -> srli rd, rd, shamt
instr_o = {7'b0, instr_i[6:2], instr_i[11:7], 3'b101, instr_i[11:7], `OPCODE_OPIMM};
if (instr_i[12] == 1'b1) illegal_instr_o = 1'b1;
if (instr_i[6:2] == 5'b0) illegal_instr_o = 1'b1;
if (instr_i[11:7] == 5'b0) illegal_instr_o = 1'b1;
end
2'b00,
2'b01: begin
// c.srai -> srai rd, rd, shamt
instr_o = {2'b01, 5'b0, instr_i[6:2], instr_i[11:7], 3'b101, instr_i[11:7], `OPCODE_OPIMM};
if (instr_i[12] != 1'b0) illegal_instr_o = 1'b1;
if (instr_i[6:2] == 5'b0) illegal_instr_o = 1'b1;
if (instr_i[11:7] == 5'b0) illegal_instr_o = 1'b1;
// 00: c.srli -> srli rd, rd, shamt
// 01: c.srai -> srai rd, rd, shamt
instr_o = {1'b0, instr_i[10], 5'b0, instr_i[6:2], 2'b01, instr_i[9:7], 3'b101, 2'b01, instr_i[9:7], `OPCODE_OPIMM};
if (instr_i[12] == 1'b1) illegal_instr_o = 1'b1;
if (instr_i[6:2] == 5'b0) illegal_instr_o = 1'b1;
if (instr_i[9:7] == 5'b0) illegal_instr_o = 1'b1;
end
2'b10: begin
// c.andi -> andi rd, rd, nzimm
instr_o = {{6 {instr_i[12]}}, instr_i[12], instr_i[6:2], instr_i[11:7], 3'b111, instr_i[11:7], `OPCODE_OPIMM};
if (instr_i[11:7] == 5'b0) illegal_instr_o = 1'b1;
// c.andi -> andi rd, rd, imm
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], `OPCODE_OPIMM};
end
2'b11: begin
unique case ({instr_i[12], instr_i[6:5]})
// c.addw
3'b000: illegal_instr_o = 1'b1;
// TODO: Merge with other similar cases (c.xor to c.and)
3'b001: begin
// c.sll -> sll rd', rd', rs2'
instr_o = {7'b000_0000, 2'b01, instr_i[4:2], 2'b01, instr_i[9:7], 3'b001, 2'b01, instr_i[9:7], `OPCODE_OP};
3'b001,
3'b100,
3'b101,
3'b110,
3'b111: begin
// 001: c.sll -> sll rd', rd', rs2'
// 100: c.xor -> xor rd', rd', rs2'
// 101: c.srl -> srl rd', rd', rs2'
// 110: c.or -> or rd', rd', rs2'
// 111: c.and -> and rd', rd', rs2'
instr_o = {7'b0, 2'b01, instr_i[4:2], 2'b01, instr_i[9:7], instr_i[12], instr_i[6:5], 2'b01, instr_i[9:7], `OPCODE_OP};
end
// c.subw
3'b010: illegal_instr_o = 1'b1;
3'b000,
3'b010: begin
// 000: c.addw
// 010: c.subw
illegal_instr_o = 1'b1;
end
3'b011: begin
// c.sub -> sub rd, rd rs2
instr_o = {2'b01, 5'b0, instr_i[6:2], instr_i[11:7], 3'b000, instr_i[11:7], `OPCODE_OP};
if (instr_i[6:2] == 5'b0) illegal_instr_o = 1'b1;
if (instr_i[11:7] == 5'b0) illegal_instr_o = 1'b1;
end
3'b100: begin
// c.xor -> xor rd', rd', rs2'
instr_o = {7'b000_0000, 2'b01, instr_i[4:2], 2'b01, instr_i[9:7], 3'b100, 2'b01, instr_i[9:7], `OPCODE_OP};
end
3'b101: begin
// c.srl -> srl rd', rd', rs2'
instr_o = {7'b000_0000, 2'b01, instr_i[4:2], 2'b01, instr_i[9:7], 3'b101, 2'b01, instr_i[9:7], `OPCODE_OP};
end
3'b110: begin
// c.or -> or rd', rd', rs2' ?
instr_o = {7'b000_0000, 2'b01, instr_i[4:2], 2'b01, instr_i[9:7], 3'b110, 2'b01, instr_i[9:7], `OPCODE_OP};
end
3'b111: begin
// c.and -> and rd', rd', rs2' ?
instr_o = {7'b000_0000, 2'b01, instr_i[4:2], 2'b01, instr_i[9:7], 3'b111, 2'b01, instr_i[9:7], `OPCODE_OP};
// c.sub -> sub rd', rd', rs2'
instr_o = {2'b01, 5'b0, 2'b01, instr_i[4:2], 2'b01, instr_i[9:7], 3'b000, 2'b01, instr_i[9:7], `OPCODE_OP};
end
endcase
end
@ -212,7 +194,7 @@ module compressed_decoder
end
end else begin
// c.add -> add rd, rd, rs2
instr_o = {7'b0, instr_i[6:2], instr_i[11:7], 3'b000, instr_i[11:7], `OPCODE_OP};
instr_o = {7'b0, instr_i[6:2], instr_i[11:7], 3'b0, instr_i[11:7], `OPCODE_OP};
if (instr_i[11:7] == 5'b0) begin
// c.ebreak -> ebreak