# YARV Bytecode Documentation

**URL:** <https://www.ruby-forum.com/t/yarv-bytecode-documentation/137714>\
**Category:** Ruby\
**Created:** [May 15, 2008, 5:19pm UTC](https://www.ruby-forum.com/t/yarv-bytecode-documentation/137714 "2008-05-15T17:19:37Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![chmaruni](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/5f8ce5/32.png) [@chmaruni](https://www.ruby-forum.com/u/chmaruni)\
**Post date:** [May 15, 2008, 5:19pm UTC](https://www.ruby-forum.com/t/yarv-bytecode-documentation/137714/1 "2008-05-15T17:19:37Z")

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Hello \*,

does anybody know any (if possible up-to-date)  
documentation/specification of the Ruby 1.9 (YARV) bytecodes? The only  
docs I could find are:

[YARV: Yet another RubyVM / Instruction Table](http://www.atdot.net/yarv/insnstbl.html) (a simple table of the opcodes)

and

[YARV: Yet another RubyVM - Software Architecture](http://www.atdot.net/yarv/yarvarch.en.html) (not much more than a table)

However, both sites seem to be outdated and are lacking some useful  
explanations (e.g., what is the op\_flag parameter for a send, and many  
more); also the sourcecode of the VM itself seems to be totally  
undocumented in that regard.

Help would be much appreciated! Thanks in advance,  
Christoph

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**Author:** ![chmaruni](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/5f8ce5/32.png) [@chmaruni](https://www.ruby-forum.com/u/chmaruni)\
**Post date:** [May 15, 2008, 5:35pm UTC](https://www.ruby-forum.com/t/yarv-bytecode-documentation/137714/2 "2008-05-15T17:35:50Z")

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Hi, check out this one:  
[http://pluskid.lifegoo.com/upload/doc/yarv/yarv\_iset.html](http://pluskid.lifegoo.com/upload/doc/yarv/yarv_iset.html)

It is generated from the current Ruby 1.9 source code, I described  
it here:  
[http://pluskid.lifegoo.com/?p=296](http://pluskid.lifegoo.com/?p=296)

On Thu, May 15, 2008 at 11:19 PM, Christoph Angerer

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**Author:** ![chmaruni](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/5f8ce5/32.png) [@chmaruni](https://www.ruby-forum.com/u/chmaruni)\
**Post date:** [May 15, 2008, 5:41pm UTC](https://www.ruby-forum.com/t/yarv-bytecode-documentation/137714/3 "2008-05-15T17:41:06Z")

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thanks, that was exactly what I was searching for:)