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More compressed instructions and fixes for existing ones

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This commit is contained in:
Sven Stucki 2015-07-10 12:14:02 +02:00
parent 5c93a289ea
commit 0d59ca91d9
1 changed files with 20 additions and 19 deletions
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39
compressed_decoder.sv
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@ -69,7 +69,7 @@ module compressed_decoder
3'b011: begin
unique case ({instr_i[12:10], instr_i[6:5]})
5'b00001: begin
5'b00000: begin
// c.xor -> xor rd', rd', rs2'
instr_o = {7'b0, 2'b01, instr_i[4:2], 2'b01, instr_i[9:7], 3'b100, 2'b01, instr_i[9:7], `OPCODE_OP};
end
@ -102,20 +102,22 @@ module compressed_decoder
unique case (instr_i[15:13])
3'b000: begin
// c.slli -> slli rd, rd, shamt
instr_o = {7'b0, instr_i[12], instr_i[6:2], instr_i[11:7], 3'b001, instr_i[11:7], `OPCODE_OPIMM};
instr_o = {6'b0, instr_i[12], instr_i[6:2], instr_i[11:7], 3'b001, instr_i[11:7], `OPCODE_OPIMM};
if (instr_i[11:7] == 5'b0) illegal_instr_o = 1'b1;
if ({instr_i[12], instr_i[6:2]} == 6'b0) illegal_instr_o = 1'b1;
if (instr_i[12] == 1'b1 || instr_i[6:2] == 5'b0) illegal_instr_o = 1'b1;
end
3'b010: begin
// c.swsp -> sw rs2, imm(x2)
instr_o = {4'b0, instr_i[8:7], instr_i[12], instr_i[6:2], 5'h02, 3'b000, instr_i[11:9], 2'b00, `OPCODE_STORE};
instr_o = {4'b0, instr_i[8:7], instr_i[12], instr_i[6:2], 5'h02, 3'b010, instr_i[11:9], 2'b00, `OPCODE_STORE};
end
3'b100: begin
unique case (instr_i[6:5])
// c.orin -> ori rd', rs1', imm
2'b10: instr_o = {{8 {instr_i[12]}}, instr_i[12:10], 2'b01, instr_i[9:7], 3'b110, 2'b01, instr_i[4:2], `OPCODE_OPIMM};
// c.andin -> andi rd', rs1', imm
2'b11: instr_o = {{8 {instr_i[12]}}, instr_i[12:10], 2'b01, instr_i[9:7], 3'b111, 2'b01, instr_i[4:2], `OPCODE_OPIMM};
default: illegal_instr_o = 1'b1;
endcase
if (instr_i[12:10] == 3'b0) illegal_instr_o = 1'b1;
@ -147,9 +149,10 @@ module compressed_decoder
instr_o = {instr_i[12], instr_i[11:7], instr_i[2], instr_i[6:3], {9 {instr_i[12]}}, 4'b0, instr_i[13], `OPCODE_JAL};
end
3'b011: begin
// c.bnez -> bne rs1', x0, imm
instr_o = {{3 {instr_i[12]}}, instr_i[12:10], instr_i[2], 5'b0, 2'b01, instr_i[9:7], 3'b001, instr_i[6:3], instr_i[12], `OPCODE_BRANCH};
3'b010, 3'b011: begin
// 0: c.beqz -> beq rs1', x0, imm
// 1: c.bnez -> bne rs1', x0, imm
instr_o = {{3 {instr_i[12]}}, instr_i[12:10], instr_i[2], 5'b0, 2'b01, instr_i[9:7], 2'b00, instr_i[13], instr_i[6:3], instr_i[12], `OPCODE_BRANCH};
end
3'b100: begin
@ -158,19 +161,23 @@ module compressed_decoder
instr_o = {12'b0, instr_i[11:7], 3'b0, 5'b0, `OPCODE_JALR};
end else begin
// c.li -> addi rd, x0, nzimm
instr_o = {6'b0, instr_i[12], instr_i[6:2], 5'b0, 3'b0, instr_i[11:7], `OPCODE_OPIMM}; // TODO: sign-extend
instr_o = {{6 {instr_i[12]}}, instr_i[12], instr_i[6:2], 5'b0, 3'b0, instr_i[11:7], `OPCODE_OPIMM};
end
if (instr_i[11:7] == 5'b0) illegal_instr_o = 1'b1;
end
3'b101: begin
// c.jalr -> jalr x1, rs1, 0
instr_o = {12'b0, instr_i[11:7], 3'b000, 5'b00001, `OPCODE_JALR};
if ({instr_i[12], instr_i[6:2]} == 6'b0) begin
// c.jalr -> jalr x1, rs1, 0
instr_o = {12'b0, instr_i[11:7], 3'b000, 5'b00001, `OPCODE_JALR};
end else begin
// c.lui -> lui rd, imm
instr_o = {{15 {instr_i[12]}}, instr_i[6:2], instr_i[11:7], `OPCODE_LUI};
end
if (instr_i[11:7] == 5'b0) illegal_instr_o = 1'b1;
end
// c.lui
3'b110: begin
if (instr_i[11:7] == 5'b0) begin
// c.addi16sp -> addi x2, x2, nzimm
@ -184,7 +191,7 @@ module compressed_decoder
3'b111: begin
// c.andi -> andi rd, rd, nzimm
instr_o = {6'b0, instr_i[12], instr_i[6:2], instr_i[11:7], 3'b111, instr_i[11:7], `OPCODE_OPIMM};
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;
end
@ -199,12 +206,6 @@ module compressed_decoder
instr_o = instr_i;
is_compressed_o = 1'b0;
end
default: begin
instr_o = 32'b0;
is_compressed_o = 1'b0;
illegal_instr_o = 1'b1;
end
endcase
end