I've created an ascii85 encoder/decoding gem with native C extensions that is compatible with the pdf-reader gem. It was taking about 10 minutes to parse hundreds of small pdf files before, now it completes in under a minute.

Gem: https://rubygems.org/gems/ascii85_native

Gem Repo: https://github.com/AnomalousBit/ascii85_native

Here's my fork of pdf-reader that uses the new ascii85_native gem: https://github.com/AnomalousBit/pdf-reader

Description

The basic need for a binary-to-text encoding comes from a need to communicate arbitrary binary data over preexisting communications protocols that were designed to carry only English language human-readable text. This is why we have things like Base64 encoded email and Usenet attachments - those media were designed only for text.

Multiple competing proposals appeared during the net's explosive growth days, before many standards emerged either by consensus or committee. Unlike the well known Base64 algorithm, ASCII85 inflates the size of the original data by only 25%, as opposed to the 33% that Base64 does.

When encoding, each group of 4 bytes is taken as a 32-bit binary number, most significant byte first (Ascii85 uses a big-endian convention). This is converted, by repeatedly dividing by 85 and taking the remainder, into 5 radix-85 digits. Then each digit (again, most significant first) is encoded as an ASCII printable character by adding 33 to it, giving the ASCII characters 33 ("!") through 117 ("u").

Take the following example word "sure". Encoding using the above method looks like this:

So in ASCII85 "sure" becomes "F*2M7". To decode, you reverse this process. Null bytes are used in standard ASCII85 to pad it to a multiple of four characters as input if needed.

Your challenge today is to implement your own routines (not using built-in libraries, for example Python 3 has a85encode and a85decode) to encode and decode ASCII85.

(Edited after posting, a column had been dropped in the above table going from four bytes of input to five bytes of output. Fixed.)

Challenge Input

You'll be given an input string per line. The first character of the line tells your to encode (e) or decode (d) the inputs.

e Attack at dawn
d 87cURD_*#TDfTZ)+T
d 06/^V@;0P'E,ol0Ea`g%AT@
d 7W3Ei+EM%2Eb-A%DIal2AThX&+F.O,EcW@3B5\\nF/hR
e Mom, send dollars!
d 6#:?H$@-Q4EX`@b@<5ud@V'@oDJ'8tD[CQ-+T

Challenge Output

6$.3W@r!2qF<G+&GA[
Hello, world

Ive tried searching for a external library to encode and decode ascii85 strings, but so far no luck, does anyone know of a way to do this?

I don't want to step on anybody's toes here, but the amount of non-dad jokes here in this subreddit really annoys me. First of all, dad jokes CAN be NSFW, it clearly says so in the sub rules. Secondly, it doesn't automatically make it a dad joke if it's from a conversation between you and your child. Most importantly, the jokes that your CHILDREN tell YOU are not dad jokes. The point of a dad joke is that it's so cheesy only a dad who's trying to be funny would make such a joke. That's it. They are stupid plays on words, lame puns and so on. There has to be a clever pun or wordplay for it to be considered a dad joke.

Again, to all the fellow dads, I apologise if I'm sounding too harsh. But I just needed to get it off my chest.

Do your worst!

They were cooked in Greece.

I'm surprised it hasn't decade.

Don't you know a good pun is its own reword?

Two muffins are in an oven, one muffin looks at the other and says "is it just me, or is it hot in here?"

Then the other muffin says "AHH, TALKING MUFFIN!!!"

For context I'm a Refuse Driver (Garbage man) & today I was on food waste. After I'd tipped I was checking the wagon for any defects when I spotted a lone pea balanced on the lifts.

I said "hey look, an escaPEA"

No one near me but it didn't half make me laugh for a good hour or so!

Edit: I can't believe how much this has blown up. Thank you everyone I've had a blast reading through the replies 😂

It really does, I swear!

Because she wanted to see the task manager.

But that’s comparing apples to oranges

Heard they've been doing some shady business.

but then I remembered it was ground this morning.

Edit: Thank you guys for the awards, they're much nicer than the cardboard sleeve I've been using and reassures me that my jokes aren't stale

Edit 2: I have already been made aware that Men In Black 3 has told a version of this joke before. If the joke is not new to you, please enjoy any of the single origin puns in the comments

And boy are my arms legs.

BamBOO!

They’re on standbi

A play on words.

My daughter, Chewbecca, not so much.

Pilot on me!!

Christopher Walken

Nothing, he was gladiator.

Or would that be too forward thinking?

Dad jokes are supposed to be jokes you can tell a kid and they will understand it and find it funny.

This sub is mostly just NSFW puns now.

If it needs a NSFW tag it's not a dad joke. There should just be a NSFW puns subreddit for that.

Edit* I'm not replying any longer and turning off notifications but to all those that say "no one cares", there sure are a lot of you arguing about it. Maybe I'm wrong but you people don't need to be rude about it. If you really don't care, don't comment.

What did 0 say to 8 ?

" Nice Belt "

So What did 3 say to 8 ?

" Hey, you two stop making out "

When I got home, they were still there.

Hindus, on the other hand, never had any beef.

I won't be doing that today!

This morning, my 4 year old daughter.

Daughter: I'm hungry

Me: nerves building, smile widening

Me: Hi hungry, I'm dad.

She had no idea what was going on but I finally did it.

Thank you all for listening.

[Removed]

There hasn't been a post all year!

Where ever you left it 🤷‍♀️🤭

And then shook his arm really fast.

(True story, please groan with me.)

You take away their little brooms