package main import ( "encoding/binary" "fmt" "io" "os" ) type J1 struct { dsp uint16 // 5 bit Data stack pointer st0 uint16 // 5 bit Return stack pointer pc uint16 // 13 bit rsp uint16 // 5 bit dstack [0x20]uint16 // Data stack rstack [0x20]uint16 // Return stack memory [0x8000]uint16 } func (vm *J1) ReadFile(fname string) error { fd, err := os.Open(fname) if err != nil { return err } defer fd.Close() stat, err := fd.Stat() if err != nil { return err } size := stat.Size() >> 1 err = binary.Read(fd, binary.BigEndian, vm.memory[:size]) if err != io.ErrUnexpectedEOF { return err } return nil } func (vm *J1) Eval() { fmt.Printf("PC: %0.4X\n", vm.pc<<1) ins := Decode(vm.memory[vm.pc]) switch v := ins.(type) { case Lit: vm.dsp += 1 vm.pc += 1 fmt.Println(v) case Jump: vm.pc = uint16(v) fmt.Println(v) case Cond: vm.pc = uint16(v) fmt.Println(v) case Call: vm.rstack[vm.rsp] = vm.pc + 1 vm.rsp += 1 vm.pc = uint16(v) fmt.Println(v) case ALU: vm.st0 = vm.ST0(v) vm.dsp = uint16(int8(vm.dsp) + v.Ddir) vm.rsp = uint16(int8(vm.rsp) + v.Rdir) vm.pc += 1 fmt.Println(v) } } func (vm *J1) ST0(v ALU) uint16 { T := vm.st0 N := vm.dstack[vm.dsp] R := vm.rstack[vm.rsp] switch v.Opcode { case 0: // T return T case 1: // N return N case 2: // T+N return T + N case 3: // T&N return T & N case 4: // T|N return T | N case 5: // T^N return T ^ N case 6: // ~T return ^T case 7: // N==T if N == T { return 1 } return 0 case 8: // N>T return N >> (T & 0xf) case 10: // T-1 return T - 1 case 11: // R (rT) return R case 12: // [T] return vm.memory[T] case 13: // N<