Malbolge

Programming in Malbolge

Example programs

Hello, World!

 "Fh
cat program
This program reads a string from a user and prints that string, similar to Unix cat.
 "!h%B0/.
 ~P<
 <:(8&
 66#"!~zyxwvu
 gJ%
Design
Malbolge is machine language for a ternary virtual machine, the Malbolge interpreter.
The standard interpreter and the official specification do not match perfectly. One difference is that the compiler stops execution with data outside the 33–126 range. Although this was initially considered a bug in the compiler, Ben Olmstead stated that it was intended and there was in fact "a bug in the specification".
Registers
Malbolge has three registers, a, c, and d. When a program starts, the value of all three registers is zero.
a stands for 'accumulator', set to the value written by all write operations on memory and used for standard I/O. c, the code pointer, is special: it points to the current instruction. d is the data pointer. It is automatically incremented after each instruction, but the location it points to is used for the data manipulation commands.
Pointer notation
d can hold a memory address;  is register indirect; the value stored at that address.  is similar.
Memory
The virtual machine has 59,049 memory locations that can each hold a ten-trit ternary number. Each memory location has an address from 0 to 59048 and can hold a value from 0 to 59048. Incrementing past this limit wraps back to zero.
The language uses the same memory space for both data and instructions. This was influenced by how hardware such as x86 architecture worked.
Before a Malbolge program starts, the first part of memory is filled with the program. All whitespace in the program is ignored and, to make programming more difficult, everything else in the program must start out as one of the instructions below.
The rest of memory is filled by using the crazy operation on the previous two addresses. Memory filled this way will repeat every twelve addresses.
In 2007, Ørjan Johansen created Malbolge Unshackled, a version of Malbolge which does not have the arbitrary memory limit. The hope was to create a Turing-Complete language while keeping as much in the spirit of Malbolge. No other rules are changed, and all Malbolge programs that do not reach the memory limit are completely functional.
Instructions
Malbolge has eight instructions. Malbolge figures out which instruction to execute by taking the value , adding the value of c to it, and taking the remainder when this is divided by 94. The final result tells the interpreter what to do:
After each instruction is executed, the guilty instruction gets encrypted so that it will not do the same thing next time, unless a jump just happened. Right after a jump, Malbolge will encrypt the innocent instruction just prior to the one it jumped to instead. Then, the values of both c and d are increased by one and the next instruction is executed.
''Crazy'' operation
For each ternary digit of both inputs, use the following table to get a ternary digit of the result. For example, crz 0001112220, 0120120120 gives 1001022211.
Encipherment
After an instruction is executed, the value at  will be replaced with itself mod 94. Then, the result is enciphered with one of the following two equivalent methods.
; Method 1: Find the result below. Store the ASCII code of the character below it at .
 0000000000111111111122222222223333333333444444444455555555556666666666777777777788888888889999
 0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123
 ----------------------------------------------------------------------------------------------
 9m<.TVac`uY*MK'X~xDlWP)H-Zn,.
Result
Encrypted
Result
Encrypted
Result
Encrypted
Result
Encrypted
Result
Encrypted
0
57
19
108
38
113
57
91
76
79
1
109
20
125
39
116
58
37
77
65
2
60
21
82
40
121
59
92
78
49
3
46
22
69
41
102
60
51
79
67
4
84
23
111
42
114
61
100
80
66
5
86
24
107
43
36
62
76
81
54
6
97
25
78
44
40
63
43
82
118
7
99
26
58
45
119
64
81
83
94
8
96
27
35
46
101
65
59
84
61
9
117
28
63
47
52
66
62
85
73
10
89
29
71
48
123
67
85
86
95
11
42
30
34
49
87
68
33
87
48
12
77
31
105
50
80
69
112
88
47
13
75
32
64
51
41
70
74
89
56
14
39
33
53
52
72
71
83
90
124
15
88
34
122
53
45
72
55
91
106
16
126
35
93
54
90
73
50
92
115
17
120
36
38
55
110
74
70
93
98
18
68
37
103
56
44
75'
104
-
-

Lou Scheffer's cryptanalysis of Malbolge mentions six different cycles in the permutation. They are listed here:
 33 ⇒ 53 ⇒ 45 ⇒ 119 ⇒ 78 ⇒ 49 ⇒ 87 ⇒ 48 ⇒ 123 ⇒ 71 ⇒ 83 ⇒ 94 ⇒ 57 ⇒ 91 ⇒ 106 ⇒ 77 ⇒ 65 ⇒ 59 ⇒ 92 ⇒ 115 ⇒ 82 ⇒ 118 ⇒ 107 ⇒ 75 ⇒ 104 ⇒ 89 ⇒ 56 ⇒ 44 ⇒ 40 ⇒ 121 ⇒ 35 ⇒ 93 ⇒ 98 ⇒ 84 ⇒ 61 ⇒ 100 ⇒ 97 ⇒ 46 ⇒ 101 ⇒ 99 ⇒ 86 ⇒ 95 ⇒ 109 ⇒ 88 ⇒ 47 ⇒ 52 ⇒ 72 ⇒ 55 ⇒ 110 ⇒ 126 ⇒ 64 ⇒ 81 ⇒ 54 ⇒ 90 ⇒ 124 ⇒ 34 ⇒ 122 ⇒ 63 ⇒ 43 ⇒ 36 ⇒ 38 ⇒ 113 ⇒ 108 ⇒ 39 ⇒ 116 ⇒ 69 ⇒ 112 ⇒ 68 ⇒ 33...
 37 ⇒ 103 ⇒ 117 ⇒ 111 ⇒ 120 ⇒ 58 ⇒ 37...
 41 ⇒ 102 ⇒ 96 ⇒ 60 ⇒ 51 ⇒ 41...
 42 ⇒ 114 ⇒ 125 ⇒ 105 ⇒ 42...
 50 ⇒ 80 ⇒ 66 ⇒ 62 ⇒ 76 ⇒ 79 ⇒ 67 ⇒ 85 ⇒ 73 ⇒ 50...
 70 ⇒ 74 ⇒ 70...
These cycles can be used to create loops that do different things each time and that eventually become repetitive. Lou Scheffer used this idea to create a Malbolge program that repeats anything the user inputs.
Variants
Malbolge is not Turing-complete, due to its memory limits. However, it otherwise has sequential execution, repetition, and conditional-execution. Several attempts have been made to create Turing-complete versions of Malbolge:
 Malbolge-T is a theoretical version of Malbolge that resets the input/output stream upon reaching the end, allowing for unbounded programs. Malbolge-T would be backward compatible with Malbolge.
 Malbolge Unshackled is a hopefully Turing-complete variation, allowing for programs of any length. However, due to command variations to allow for values above 257, valid Malbolge programs will not necessarily run correctly in Malbolge Unshackled.
Popular culture
In the television series Elementary, during the episode "The Leviathan", a clue written on a coffee order is described as having been written in Malbolge. It appears to be a small modification of the more verbose "Hello World" example shown above.