PDP-11 architecture

pdp11.scala

import compiletime.ops.int.S

type Nat[n <: Int] = 
  n match 
    case 0 => 0
    case S[n] =>  S[n] | Nat[n]

type Octal = Nat[7]

object Registers:
  type Flags = Nat[15]
  val N: Flags = 8
  val Z: Flags = 4
  val V: Flags = 2
  val C: Flags = 1
  extension (f: Flags) 
    inline def | (g: Flags) = f | g
    inline def & (g: Flags) = f & g
    inline def ^ (g: Flags) = f ^g 
    inline def ~ = ~f

  val a = N | Z

  extension (r: Register) inline def toOctal = r
  opaque type Register = Octal
  opaque type BasicMode <: Mode = 0 | 1 | 2 | 3
  opaque type Mode = Octal
  inline def r(i: Octal): Register = i
  val R0 = r(0)
  val R1 = r(1)
  val R2 = r(2)
  val R3 = r(3)
  val R4 = r(4)
  val R5 = r(5)
  val R6 = r(6)
  val R7 = r(7)
  inline def PC = R7
  inline def SP = R6

trait AddressingModes:
  type BasicMode
  type Mode >: BasicMode
  import Registers.*

  final given Conversion[Register, BasicMode] = _.direct

  extension (r: Register)
    def direct: BasicMode
    def inc: BasicMode
    def dec: BasicMode
    def apply(offset: Short): BasicMode

  extension (mode: BasicMode) def defer: Mode

  type Command
  type SizedCommand <: Command
  extension (s: SizedCommand) def b: Command

  type TwoArgSized = (Mode, Mode) => SizedCommand
  type TwoArg = (Mode, Mode) => Command
  val mov, cmp, bit, bic, bis: TwoArgSized
  val add, sub: TwoArg
  // TODO: mul,div, ash, ashc

  type SingleArg = Mode => Command
  type SingleArgSized = Mode => SizedCommand
  val jmp, swab, mtps, mfps, sxt: SingleArg
  val clr, com, inc, dec, neg, adc, sbc, tst, ror, rol, asr, asl: SingleArg

  type Offset = Byte
  type Branch = Offset => Command
  val br, bne, beq, bge, blt, bgt, ble, bpl, bmi, bhi, blos, bvc, bvs, bcc,
  bcs: Branch
  def sob(r: Register, off: Offset): Command

  def jsr(r: Register, addr: Mode): Command
  def rts(r: Register): Command
  def mark(n: Nat[31]): Command

  type VectorId = Nat[255]
  def emt(v: VectorId): Command
  def trap(v: VectorId): Command


  val rti, bpt, iot, rtt, halt, Wait, reset: Command //TODO: wait?

  def clearFlags(f: Flags): Command
  def setFlags(f: Flags): Command