diff --git a/horrlang.py b/horrlang.py
index 7269483..14a84b6 100755
--- a/horrlang.py
+++ b/horrlang.py
@@ -3,18 +3,50 @@
 
 import sys
 
+class InfiniteArray:
+    def __init__(self, values=None):
+        self.chunks = {}
+        if values is not None:
+            for key, value in enumerate(values):
+                self[key] = value
+
+    def get_chunk(self, index):
+        if index not in self.chunks:
+            self.chunks[index] = [0 for i in xrange(4096)]
+        return self.chunks[index]
+
+    def __getitem__(self, index):
+        return self.get_chunk(index / 4096)[index % 4096]
+
+    def __setitem__(self, index, value):
+        self.get_chunk(index / 4096)[index % 4096] = value
+
 
 class Machine:
-    def __init__(self, code):
-        self.mem = [ord(char) for char in code]
+    def __init__(self, code, read, write, user_data=None, max_cycles=None):
+        self.user_data = user_data
+        self.read = read
+        self.write = write
+        self.mem = InfiniteArray([ord(char) for char in code])
         self.exc_ptr = 0
         self.mem_ptr = 0
+        self.max_cycles = max_cycles
+        self.cycles = 0
+
+    def cycle(self):
+        self.cycles += 1
+        if self.max_cycles is not None:
+            if self.cycles >= self.max_cycles:
+                return False
+        return True
 
     def get_integer(self):
         parameter = 0
         while chr(self.mem[self.exc_ptr + 1]) >= '0' \
                 and chr(self.mem[self.exc_ptr + 1]) <= '9':
             self.exc_ptr += 1
+            if not self.cycle():
+                return parameter
             parameter = parameter * 10 + (self.mem[self.exc_ptr] \
                                               - ord('0'))
         if parameter == 0:
@@ -23,27 +55,33 @@ class Machine:
 
     def L(self):
         self.mem_ptr -= self.get_integer()
+        if self.mem_ptr < 0:
+            self.mem_ptr = 0
 
     def R(self):
         self.mem_ptr += self.get_integer()
 
     def O(self):
-        sys.stdout.write(chr(self.mem[self.mem_ptr]))
+        self.write(chr(self.mem[self.mem_ptr]))
 
     def I(self):
-        self.mem[self.mem_ptr] = ord(sys.stdin.read(1))
+        self.mem[self.mem_ptr] = ord(self.read(1))
 
     def N(self):
         self.exc_ptr += 1
         search = self.mem[self.exc_ptr]
         while self.mem[self.exc_ptr] != search:
             self.exc_ptr += 1
+            if not self.cycle():
+                return
 
     def P(self):
         search = self.mem[self.exc_ptr + 1]
         self.exc_ptr -= 1
         while self.mem[self.exc_ptr] != search:
             self.exc_ptr -= 1
+            if not self.cycle():
+                return
 
     def J(self):
         if self.mem[self.mem_ptr] != ord('0'):
@@ -51,6 +89,8 @@ class Machine:
             self.exc_ptr -= 1
             while self.mem[self.exc_ptr] != search:
                 self.exc_ptr -= 1
+                if not self.cycle():
+                    return
 
     def H(self):
         self.mem[self.mem_ptr] = self.mem[self.mem_ptr] + 1
@@ -58,13 +98,18 @@ class Machine:
     def K(self):
         self.mem[self.mem_ptr] = self.mem[self.mem_ptr] - 1
 
-    def run(self):
+    def run(self, debug=False):
         while True:
-            if self.exc_ptr >= len(self.mem):
-                sys.exit(0)
+            if self.mem[self.exc_ptr] == 0:
+                return
             control = chr(self.mem[self.exc_ptr])
+            if debug:
+                print control
             if hasattr(self, control):
                 getattr(self, control)()
             self.exc_ptr += 1
+            if not self.cycle():
+                return
 
-Machine(sys.argv[1]).run()
+if __name__ == "__main__":
+    Machine(sys.argv[1], sys.stdin.read, sys.stdout.write, None).run()