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Even more compressed instructions

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Sven Stucki 2015-07-16 17:35:49 +02:00
parent 4289008afe
commit 45f23be416
1 changed files with 20 additions and 3 deletions
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23
compressed_decoder.sv
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@ -62,6 +62,14 @@ module compressed_decoder
if (instr_i[11:7] == 5'b0) illegal_instr_o = 1'b1;
end
3'b001: 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;
end
3'b010: begin
// c.sw -> sw rs2', imm(rs1')
instr_o = {5'b0, 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, `OPCODE_STORE};
@ -72,19 +80,28 @@ module compressed_decoder
// c.xor -> xor rd', rd', rs2'
5'b00000: 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};
// c.sltr
// c.srl -> srl rd', rd', rs2'
5'b00101: instr_o = {7'b0, 2'b01, instr_i[4:2], 2'b01, instr_i[9:7], 3'b101, 2'b01, instr_i[9:7], `OPCODE_OP};
// c.sltur -> sltu rd', rs1', rd'
5'b01111: instr_o = {7'b0, 2'b01, instr_i[4:2], 2'b01, instr_i[9:7], 3'b011, 2'b01, instr_i[4:2], `OPCODE_OP};
default: illegal_instr_o = 1'b1;
endcase
end
3'b100: 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[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;
end
3'b101: begin
unique case (instr_i[6:5])
// c.add3 -> add rd', rs1', rs2'
2'b00: instr_o = {7'b0, 2'b01, instr_i[4:2], 2'b01, instr_i[9:7], 3'b000, 2'b01, instr_i[12:10], `OPCODE_OP};
// c.sub3
// c.sub3 -> sub rd', rs1', rs2'
2'b01: instr_o = {2'b01, 5'b0, 2'b01, instr_i[4:2], 2'b01, instr_i[9:7], 3'b000, 2'b01, instr_i[12:10], `OPCODE_OP};
// c.or3 -> or rd'1, rs1', rs2'
2'b10: instr_o = {7'b0, 2'b01, instr_i[4:2], 2'b01, instr_i[9:7], 3'b110, 2'b01, instr_i[12:10], `OPCODE_OP};
// c.and3 -> and rd', rs1', rs2'