BST 4   -->   B = A mod 8
 BXL 1   -->   B = B xor 1
 CDV 5  -->  C = A shr B
 BXC 6   -->  B = B xor C
 BXL 4   -->   B = B xor 4
 ADV 3  -->  A = A shr 3
 OUT 5 ---> out B                                 
 JNZ 0

 Loop:

 

 
 out -> B
 a -> shl 3
b -> b xor 4
b -> b xor C
C ->