Low-level assembly language for Malbolge

Syntax

# for comment line, i.e., all characters after # are ignored.

Sample Programs

Hello.mc

Hello_output-routine.mc

unit.mc

0Branch.mc

Semantics

Overview

------------------------------
  Declaration of ENTRY

  Declarations of FLAGs

  Declarations of UNITs

  Declarations of ROUTINEs
------------------------------

• Specifies the start point by "entry label@routine name".

  Example: PROGRAM_START_TO ENTRY@Hello

• Specifies a flag by "FLAG [initial state/cycle] label". 2，4，5，6 and 9 are allowed as a cycle. A number between 0 and cycle-1 is allowed as an initial state. Flags in state 0 are active, and Flags in the other states are inactive. The states are incremented by an execution of the flag.

  Example: FLAG [1/2] F1ag_H;

• Specifies a sequence of data (including Malbolge instructions).

• Example of a UNIT
  

  UNIT{
             58:73  # 73 is placed on an address 58 (mod 94)

    ROT2:    59:ROT # ROT instruction is placed on the address 59, referable by ROT2.
    REV_ROT2:60:JMP # JMP instruction is placed on the address 60, referable by REV_ROT2.
  }										

• Routines are sequences of (possibly labelled) data or instructions.

  ROUTINE name of routine {
    …
    Instructions or constants
    …
  }
  

• A label is a string consists of alphabet, numeric symbol and underscore that begins from an alphabet. A colon follows from a label. Constants or instructions are placed after that.

  Example:

    PUT_H: IF FLAG_H
           BRANCH PUT_e
  

• Constants are decimal numbers from 0 until 59048, ternary numbers from 0000000000t until 2222222222t, or DUP, that represents an unspecified number.

• Instructions are defined as follows, where n represents a fixed natural number, [LABEL] is the data labelled by the LABEL. D register acts as a program counter.

  Instruction	Semantics	Restriction
  ROT label	A，[label] ：= rotr( [label] )， D ：= label+1	D < label ≤ D+n
  REV ROT	recovers ROT, D ：= D+1
  OPR label	A，[label] ：= op(A，[label] )， D ：= label+1	D < label ≤ D+n
  REV OPR	recovers OPR, D ：= D+1
  SKIP label	D ：= label	D < label ≤ D+n
  JMP label	D ：= [label]
  REV JMP	recovers JMP, D ：= D+1
  OUTPUT	putchr(A); D ：= D+2
  REV OUTPUT	recovers OUTPUT, D ：= D+1
  INPUT	A ：= getchr(); D ：= D+2
  REV INPUT	recovers INPUT, D ：= D+1
  IF FLAG_name BRANCH label	If it is active, D ：= [label] ; otherwise, D ：= D+2 The state is incremented.
  NEXT FLAG_name	The state of the flag is incremented. D ：= D+1

  Remark that the recovering instructions must be executed after ROT，OPR，OUTPUT，INPUT，JMP instructions are executed.

  Remark that the label specified in an operand of an instruction must be defined below the instruction.

  Remark that DUP is typically used as a padding data for INPUT/OUTPUT.

  　　Correct example)
  

      　　ROT X
      　　X: 0120120120t
      　　REV ROT
      　　OUTPUT 
      　　DUP
      　　REV OUTPUT
  

  　　Incorrect example)
  

      　　X: 0120120120t  # The operand X of ROT is placed above ROT
      　　ROT X
      　　REV ROT
      　　OUTPUT
      　　REV OUTPUT  # this is never executed
  

  Remark that module acts only for collision of names. @routine must follow label in a different routine.