Calling Decode multiple times from same instance corrupted results

[cyotek]

Hello,

I was playing around with your Ascii85 implementation when I discovered that calling Decode multiple times from the same Ascii85 instance would cause data corruption on successive calls. For example, the following output was generated by changing TestString to call and print Decode twice

<~9jqo^BlbD-BleB1DJ+*+F(f,q/0JhKF<GL>[email protected]$d7F!,L7@<6@)/0JDEF<G%<+EV:2F!,
O<DJ+*.@<*K0@<6L(Df-\0Ec5e;DffZ(EZee.Bl.9pF"AGXBPCsi+DGm>@3BB/F*&OCAfu2/AKY
i(DIb:@FD,*)+C]U=@3BN#EcYf8ATD3s@q?d$AftVqCh[NqF<G:8+EV:.+Cf>-FD5W8ARlolDIa
l(DId<j@<?3r@:F%a+D58'ATD4$Bl@l3De:,-DJs`8ARoFb/0JMK@qB4^F!,R<AKZ&-DfTqBG%G
>uD.RTpAKYo'+CT/5+Cei#DII?(E,9)oF*2M7/c~>

Encoded in 345 chars

Man is distinguished, not only by his reason, but by this singular passion from other animals, which is a lust of the mind, that by a perseverance of delight in the continued and indefatigable generation of knowledge, exceeds the short vehemence of any carnal pleasure.

Decoded 269 chars

{d??is distinguished, not only by his reason, but by this singular passion from other animals, which is a lust of the mind, that by a perseverance of delight in the continued and indefatigable generation of knowledge, exceeds the short vehemence of any carnal pleasure.

You can see the first few characters in the second call have been corrupted. I first spotted this when storing encoded passwords in an XML file then wondering why they weren't working anymore after successive saves :)

Fortunately the fix was simple - so simple it seems a little absurd creating a pull request (especially given it was a demo to accompany your blog post), but that seems to be the GitHub way. Basically, the Decode method needs to reset the _tuple instance variable back to 0 prior to doing its thing, and successive calls then work fine without the corruption. (At least I hope so, I haven't really grokked how it truly works).

Thanks for providing the helpful class!

Regards;
Richard Moss

[graingert]

@cyotek is this bug in SimpleBase?

@coding-horror it might be worth archiving this project now that it's pointing to SimpleBase