Editing Threaded code (section)

===Huffman threading===
Huffman threaded code consists of lists of tokens stored as [[Huffman code]]s. A Huffman code is a variable-length string of bits that identifies a unique token. A Huffman-threaded interpreter locates subroutines using an index table or a tree of pointers that can be navigated by the Huffman code. Huffman-threaded code is one of the most compact representations known for a computer program. The index and codes are chosen by measuring the frequency of calls to each subroutine in the code. Frequent calls are given the shortest codes. Operations with approximately equal frequencies are given codes with nearly equal bit-lengths. Most Huffman-threaded systems have been implemented as direct-threaded Forth systems, and used to pack large amounts of slow-running code into small, cheap [[microcontroller]]s. Most published<ref name=huffman>{{cite book |last1=Latendresse |first1=Mario |last2=Feeley |first2=Marc |title=Generation of Fast Interpreters for Huffman-Compressed Bytecode |citeseerx=10.1.1.156.2546 |publisher=Elsevier}}</ref> uses have been in smart cards, toys, calculators, and watches. The bit-oriented tokenized code used in [[PBASIC]] can be seen as a kind of Huffman-threaded code.