Making all your integers positive with zigzag encoding

Re:Making all your integers positive with zigzag encoding by phoboslab on Friday November 25, 2022 @02:25PM (#33745892)

I first encountered this in the Flac source[1]. They do the bit twiddling a bit differently than in this article:

    uval = (val<<1) ^ (val>>31);

Variations of this have probably been used countless of times in other libraries.

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Re:Making all your integers positive with zigzag encoding by jamesmunns on Friday November 25, 2022 @02:58PM (#33746163)

Author of postcard here, I don't remember exactly where I got my bit twiddling example from, lemme see if I have notes from that.

postcard's zigzag encoding matches phoboslab's psuedocode.

Edit, not totally sure, but this wiki page rings a bell, and is probably where I got my impl from: https://en.wikipedia.org/wiki/Variable-length_quantity#Zigza...

Edit 2: I also explain why I do this (it compresses better) in my wire format specification: https://postcard.jamesmunns.com/wire-format.html#signed-inte...

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