How does Digest, digest-md5 extension implemented?

When I look at the Rhodes system sample, it seems that Rhodes support digest sha1 and digest md5:

require 'digest'

require 'digest/md5'

require 'digest/sha1'

But I did not find the implementation for the above 3 extensions, in the Rhomobile folder,


I saw 4 folders: digest, digest-md5, digest-sha1, digest-sha2.

But when I enter into each folder, digest-sha1, digest-md5, and digest-sha2, the .rb file in these folders are empty.

and they only have iphone port of native extension.

So based on the above I don't know if digest- extension is really support or not in Rhodes, or they are only support in iphone, not other platforms?

If they are supported, why I can not see the ruby code? and Where can I see the API document?

Can some explain to me how those digest- extensions are implemented in Rhodes?