The use of codepoints below 32 (space, start of what's usually considered "printable") makes me a bit hesitant. A lot of systems won't preserve those characters. Base85 is a more efficient alternative to base64, and doesn't use that lower range:
This was true on Vax 8200 hardware back in the day. In the same software, with Huffman decoding of JPEGs it was also fastest to create a finite state machine with an 8 bit symbol size. I suspect that is no longer true since it would kill your L1 cache and be well into your L2 cache on modern x86 machines. It is probably better to take the instruction count hit and process as bits or nibbles.
Still useful for Javascript, as the bit shift operators work on 32 bit "registers".
Stick with the characters that nearly everyone assumes could legitimately come up in a document and your chances of running afoul of some "creative genius" who decided "Hey its unprintable so no one will try to print it, but when I do print it I want this thing to happen..."
[1] http://grepcode.com/file/repository.grepcode.com/java/root/j...
http://www.emergencevector.com/
It's pretty easy to write the decode for the 0-91 integer in Javascript.
if (ch == "!") {
return 57;
} else {
return ch.charCodeAt(0) - 35;
}
I'm probably going to go to typed arrays of 32 bit values. Currently, I can encode an entire ship's data in 18 bytes, of which 4 characters is a hash id.