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54 lines
1.9 KiB
54 lines
1.9 KiB
# varint
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encode whole numbers to an array of [protobuf-style varint bytes](https://developers.google.com/protocol-buffers/docs/encoding#varints) and also decode them.
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```javascript
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var varint = require('varint')
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var bytes = varint.encode(300) // === [0xAC, 0x02]
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varint.decode(bytes) // 300
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varint.decode.bytes // 2 (the last decode() call required 2 bytes)
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```
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## api
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### varint = require('varint')
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### varint.encode(num[, buffer=[], offset=0]) -> buffer
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Encodes `num` into `buffer` starting at `offset`. returns `buffer`, with the encoded varint written into it. If `buffer` is not provided, it will default to a new array.
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`varint.encode.bytes` will now be set to the number of bytes
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modified.
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### varint.decode(data[, offset=0]) -> number
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decodes `data`, which can be either a buffer or array of integers, from position `offset` or default 0 and returns the decoded original integer.
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Throws a `RangeError` when `data` does not represent a valid encoding.
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### varint.decode.bytes
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if you also require the length (number of bytes) that were required to decode the integer you can access it via `varint.decode.bytes`. this is an integer property that will tell you the number of bytes that the last .decode() call had to use to decode.
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### varint.encode.bytes
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similar to `decode.bytes` when encoding a number it can be useful to know how many bytes where written (especially if you pass an output array). you can access this via `varint.encode.bytes` which holds the number of bytes written in the last encode.
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### varint.encodingLength(num)
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returns the number of bytes this number will be encoded as, up to a maximum of 8.
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## usage notes
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If varint is passed a buffer that does not contain a valid end
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byte, then `decode` will throw `RangeError`, and `decode.bytes`
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will be set to 0. If you are reading from a streaming source,
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it's okay to pass an incomplete buffer into `decode`, detect this
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case, and then concatenate the next buffer.
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# License
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MIT
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