diff options
| author | David Li <li.davidm96@gmail.com> | 2015-12-26 21:58:24 -0700 |
|---|---|---|
| committer | David Li <li.davidm96@gmail.com> | 2015-12-26 21:58:24 -0700 |
| commit | ccac1d5977e913ef0d3317e3e3074912e6ba59b2 (patch) | |
| tree | e0323bd8aa4a21f9a299c41c718dc073c0ba34db | |
| parent | 05ae121c98be750aeca537ded7338c0cbf5f5b4c (diff) | |
Reenable jump/branch instructions
| -rw-r--r-- | src/simulator.rs | 76 |
1 files changed, 39 insertions, 37 deletions
diff --git a/src/simulator.rs b/src/simulator.rs index 127ac8a..277e52f 100644 --- a/src/simulator.rs +++ b/src/simulator.rs @@ -98,20 +98,22 @@ impl Simulator { let pc = core.pc; if let Some(inst) = self.memory.read_instruction(pc) { match inst.opcode() { - // isa::opcodes::JALR => { - // // TODO: assert funct3 is 0 - // let target = ((core.registers.read_word(inst.rs1()) as isa::SignedWord) + inst.i_imm()) as isa::Address; - // if target == 0x0 { - // // ret - // core.running = false; - // } - // else { - // let target = (((pc as isa::SignedWord) + inst.i_imm()) as isa::Address) & 0xFFFFFFFE; - // core.registers.write_word(inst.rd(), (pc + 4) as isa::Word); - // core.pc = target; - // return; - // } - // }, + isa::opcodes::JALR => { + // TODO: assert funct3 is 0 + let base = core.registers.read_word(inst.rs1()) + as isa::SignedWord; + let target = (base + inst.i_imm()) as isa::Address; + let retval = (pc + 4) as isa::Word; + if target == 0x0 { + // ret + core.running = false; + } + else { + core.registers.write_word(inst.rd(), retval); + core.pc = target; + return; + } + }, isa::opcodes::JAL => { let target = ((pc as isa::SignedWord) + inst.uj_imm()) as isa::Address; core.registers.write_word(inst.rd(), (pc + 4) as isa::Word); @@ -119,29 +121,29 @@ impl Simulator { // panic!("JAL to {:X} 0x{:X}", pc, target); return; } - // isa::opcodes::BRANCH => { - // let target = ((pc as isa::SignedWord) + inst.sb_imm()) as isa::Address; - // let rs1 = core.registers.read_word(inst.rs1()); - // let rs2 = core.registers.read_word(inst.rs2()); - // if match inst.funct3() { - // isa::funct3::BEQ => rs1 == rs2, - // isa::funct3::BNE => rs1 != rs2, - // isa::funct3::BLT => (rs1 as isa::SignedWord) < (rs2 as isa::SignedWord), - // isa::funct3::BGE => (rs1 as isa::SignedWord) > (rs2 as isa::SignedWord), - // isa::funct3::BLTU => rs1 < rs2, - // isa::funct3::BGEU => rs1 > rs2, - // _ => { - // self.trap(core, Trap::IllegalInstruction { - // address: pc, - // instruction: inst, - // }); - // false - // } - // } { - // core.pc = target; - // return; - // } - // }, + isa::opcodes::BRANCH => { + let target = ((pc as isa::SignedWord) + inst.sb_imm()) as isa::Address; + let rs1 = core.registers.read_word(inst.rs1()); + let rs2 = core.registers.read_word(inst.rs2()); + if match inst.funct3() { + isa::funct3::BEQ => rs1 == rs2, + isa::funct3::BNE => rs1 != rs2, + isa::funct3::BLT => (rs1 as isa::SignedWord) < (rs2 as isa::SignedWord), + isa::funct3::BGE => (rs1 as isa::SignedWord) > (rs2 as isa::SignedWord), + isa::funct3::BLTU => rs1 < rs2, + isa::funct3::BGEU => rs1 > rs2, + _ => { + self.trap(core, Trap::IllegalInstruction { + address: pc, + instruction: inst, + }); + false + } + } { + core.pc = target; + return; + } + }, isa::opcodes::INTEGER_IMMEDIATE => { let imm = inst.i_imm(); let src = core.registers.read_word(inst.rs1()) as isa::SignedWord; |