This is a Befunge-93 interpreter written in python 3.4 with the use of pygame. The code has not properly been tested on python 2.X.

Johan Asplund

How to use

Run the script as python befunge.py arg1 arg2, where arg1 is the befunge code, and where arg2 is an integer specifying the time between each iteration (one iteration = one step of the cursor) which defaults to 50 ms.

Controls

• space to pause the code
• r to reset the code
• right arrow to step once
• esc to quit

TODO

• Add syntax coloring
• Maybe promt the user for inputs in some other way than in the terminal
• Prevent the output to go off screen

Other notes

The font Inconsolata, which is used in the interpreter, is owned by Raph Levien.

Quick reference for Befunge-93

Character	Description
0-9	Push this number to the stack
+	Pop a and b, then push a+b.
-	Pop a and b, then push a-b.
*	Pop a and b, then push a*b.
/	Pop a and b, then push floor(b/a), provided that a is not zero.
%	Pop a and b, then push a (mod b).
!	Pop a. If a = 0, push 1, otherwise push 0.
`	Pop a and b, then push 1 if b > a, otherwise 0.
>	Move right.
`<^	Move left.
^	Move up.
v	Move down.
?	Move in a random direction.
_	Pop a. If a = 0, move right, otherwise move left.
|	Pop a. If a = 0 , move down, otherwise move up.
"	Start string mode. Push each characters ASCII value all the way up to the next ".
:	Duplicate value on top of the stack.
\	Swap the two values on top of the stack.
$	Remove the value on top of the stack.
.	Pop a. Output the integer value of a.
,	Pop a. Output chr(a).
#	Skip next cell.
p	Pop y, y and v. Change the character in position (x,y) to chr(v).
g	Pop y and x , the push the ASCII value of the character in position (x,y).
&	Prompt user for a number and push it.
~	Prompt user for a character and push its ASCII value.
@	Stop instruction pointer