Threaded code: Difference between revisions

Revision as of 19:31, 3 August 2023

Revision as of 19:43, 3 August 2023

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===RPL===

[[Hewlett-Packard|HP]]'s [[RPL (programming language)|RPL]], first introduced in the [[HP-18C]] calculator in 1986, is a type of proprietary hybrid (direct-threaded and indirect-threaded) ''threaded interpretive language'' (TIL)<ref name="Loelinger_1981"/> that, unlike other TILs, allows embedding of RPL "objects" into the "runstream", i.e. the stream of addresses through which the interpreter pointer advances. An RPL "object" can be thought of as a special data type whose in-memory structure contains an address to an "object prolog" at the start of the object, and then data or executable code follows. The object prolog determines how the object's body should be executed or processed. Using the "RPL inner loop",<ref name="RPL1Busby_2018">Busby, Jonathan. [https://www.hpmuseum.org/forum/thread-11358.html "The RPL inner loop explained"], [http://www.hpmuseum.org/ "The Museum of HP Calculators"], 7 September 2018, Retrieved on 27 December 2019</ref> which was invented and published (and patented<ref>{{cite web |author-lastname=Wickes |author-first=William C. |title=Data processing system and method for the direct and indirect execution of uniformly structured object types |website=uspto.gov |date=30 May 1986 |url=http:"Wickes_1986"//patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.htm&r=8&p=1&f=G&l=50&d=PTXT&S1=((%22Hewlett+Packard%22.ASNM.)+AND+Wickes.INNM.)&OS=AN/%22Hewlett+Packard%22+and+IN/Wickes&RS=(AN/%22Hewlett+Packard%22+AND+IN/Wickes) |access-date = 27 December 2019}}</ref>) by William C. Wickes in 1986 and published in "Programming Environments", Institute for Applied Forth Research, Inc., 1988, execution follows like so:<ref name="Wickes_1988"/>

# Dereference the IP (instruction pointer) and store it into O (current object pointer)

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</pre>

On HP's [[HP Saturn|Saturn]] microprocessors that use RPL, there is a third level of indirection made possible by an architectural / programming trick which allows faster execution.<ref name="RPL1Busby_2018"/>

==Branches==

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{{reflist|refs=

<ref name="Loelinger_1981">{{cite book |title=Threaded Interpretive Languages: Their Design and Implementation |author-first=R. G. |author-last=Loelinger |___location=Dayton, Ohio, USA |edition=2nd printing, 1st |date=1981 |orig-date=August 1979 |publisher=[[BYTE Books]], [[BYTE Publications Inc.]] |publication-place=Peterborough, New Hampshire, UK |isbn=0-07038360-X |id={{ISBN|978-0-07038360-9}} |lccn=80-19392 |id={{ISBN|978-0-07038360-9}} |url=https://archive.org/details/R.G.LoeligerThreadedInterpretiveLanguagesTheirDesignAndImplementationByteBooks1981 |access-date=2023-08-03}} (xvi+251 pages)</ref>

<ref name="Busby_2018">Busby, Jonathan. [https://www.hpmuseum.org/forum/thread-11358.html "The RPL inner loop explained"], [http://www.hpmuseum.org/ "The Museum of HP Calculators"], 7 September 2018, Retrieved on 27 December 2019</ref>

<ref name="Wickes_1986">{{cite web |author-last=Wickes |author-first=William C. |title=Data processing system and method for the direct and indirect execution of uniformly structured object types |website=uspto.gov |date=1986-05-30 |url=http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.htm&r=8&p=1&f=G&l=50&d=PTXT&S1=((%22Hewlett+Packard%22.ASNM.)+AND+Wickes.INNM.)&OS=AN/%22Hewlett+Packard%22+and+IN/Wickes&RS=(AN/%22Hewlett+Packard%22+AND+IN/Wickes) |access-date=2019-12-27}}</ref>

<ref name="Wickes_1988">William C. Wickes, "Programming Environments", Institute for Applied Forth Research, Inc., 1988</ref>

}}