open Base

let symbols =
  Map.of_alist_exn
    (module String)
    [ "R0", 0
    ; "R1", 1
    ; "R2", 2
    ; "R3", 3
    ; "R4", 4
    ; "R5", 5
    ; "R6", 6
    ; "R7", 7
    ; "R8", 8
    ; "R9", 9
    ; "R10", 10
    ; "R11", 11
    ; "R12", 12
    ; "R13", 13
    ; "R14", 14
    ; "R15", 15
    ; "SP", 0
    ; "LCL", 1
    ; "ARG", 2
    ; "THIS", 3
    ; "THAT", 4
    ; "SCREEN", 16384
    ; "KBD", 24576
    ]
;;

let comp c =
  match c with
  | "0" -> "0101010"
  | "1" -> "0111111"
  | "-1" -> "0111010"
  | "D" -> "0001100"
  | "A" -> "0110000"
  | "M" -> "1110000"
  | "!D" -> "0001101"
  | "!A" -> "0110001"
  | "!M" -> "1110001"
  | "-D" -> "0001111"
  | "-A" -> "0110011"
  | "-M" -> "1110011"
  | "D+1" -> "0011111"
  | "A+1" -> "0110111"
  | "M+1" -> "1110111"
  | "D-1" -> "0001110"
  | "A-1" -> "0110010"
  | "M-1" -> "1110010"
  | "D+A" -> "0000010"
  | "D+M" -> "1000010"
  | "D-A" -> "0010011"
  | "D-M" -> "1010011"
  | "A-D" -> "0000111"
  | "M-D" -> "1000111"
  | "D&A" -> "0000000"
  | "D&M" -> "1000000"
  | "D|A" -> "0010101"
  | "D|M" -> "1010101"
  | _ -> failwith "Unknown COMP Instruction"
;;

let dest d =
  match d with
  | "" -> "000"
  | "M" -> "001"
  | "D" -> "010"
  | "MD" -> "011"
  | "A" -> "100"
  | "AM" -> "101"
  | "AD" -> "110"
  | "ADM" -> "111"
  | _ -> failwith "Unknown DEST Instruction"
;;

let jump j =
  match j with
  | "" -> "000"
  | "JGT" -> "001"
  | "JEQ" -> "010"
  | "JGE" -> "011"
  | "JLT" -> "100"
  | "JNE" -> "101"
  | "JLE" -> "110"
  | "JMP" -> "111"
  | _ -> failwith "Unknown JUMP Instruction"
;;