Szewczyk notation for Minsky machine

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Szewczyk notation is a tool of thought useful when describing counter machines. Simply put, this notation for Minsky machine is a minimalistic representation of its capabilities.

Syntax

Minsky machine code is represented by a list of pairs separated from each other. The text representation looks like this:

a0 a1
b0 b1
c0 c1
 ...

Each row is given an unique, consecutive ID. The notation supports two instructions:

  • inc rX => X -1: increment register rX
  • dec rX, Y => X Y: decrement register rX if rX > 0, else jump to row with ID Y.

Properties

Numbers can be assumed of infinite precision. The ID's are 0 indexed and registers are initialized to 0

Examples

Infinite loop:

1 -1
1 1
1 1

Interpreter

A tiny, 321 byte Perl emulator for the Minsky machine code (assuming Szewczyk notation).

#!/usr/bin/perl
use bignum;my(@a,@c,$d);push(@a,0)for(1..$ARGV[0]);s/(-?[0-9]+)[ \t]+(-?[0-9]+)/push(@{$c[$d++]},($1,$2));/ge while(<STDIN>);
for($d=0;$d<@c;$d++){$a[$c[$d][0]]++if$c[$d][1]==-1;if($c[$d][1]>=0){$d=$c[$d][1]-1if($a[$c[$d][0]]==0);$a[$c[$d][0]]--if($a[
$c[$d][0]]>0);}}print((shift@a)."\n")for(1..$ARGV[0]);

Extensions

An I/O extension can be implemented as x1 equal to -2 (for output) and -3 (for input) to a given register.