Yjs varint encoding

y-protocol defines protocol that is used when exchanging data between yjs clients^[1].

Yjs uses varint to encode content, which is similar in protobuf. Yjs encodes unsigned integer within range of 0-2^53-1, which is the max number supported by javascript^[2].

123456=0b111|1000100|1000000
->(1)1000000|(1)1000100|(0)____111
-> 0xc0     | 0xc4     | 0x07

The first bit indicates that whether there's a continuous byte, if it's 0, then the number is finished.

In short, the protocol defines the following methods:

varUint(number)
varByteArray(buffer) := varUint(length(buffer)) • buffer
utf8(string)
varString(string) := varByteArray(utf8(string))
json(object) := varString(JSON.stringify(object))

Online tool to calculate varUint encoding: https://bluecrewforensics.com/varint-converter/

[1] ttps://github.com/yjs/y-protocols/blob/master/PROTOCOL.md

[2] ttps://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Number/MAX_SAFE_INTEGER

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