You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
54 lines
1.9 KiB
54 lines
1.9 KiB
1 month ago
|
# varint
|
||
|
|
|
||
|
|
encode whole numbers to an array of [protobuf-style varint bytes](https://developers.google.com/protocol-buffers/docs/encoding#varints) and also decode them.
|
||
|
|
|
||
|
|
```javascript
|
||
|
|
var varint = require('varint')
|
||
|
|
|
||
|
|
var bytes = varint.encode(300) // === [0xAC, 0x02]
|
||
|
|
varint.decode(bytes) // 300
|
||
|
|
varint.decode.bytes // 2 (the last decode() call required 2 bytes)
|
||
|
|
```
|
||
|
|
|
||
|
|
## api
|
||
|
|
|
||
|
|
### varint = require('varint')
|
||
|
|
|
||
|
|
### varint.encode(num[, buffer=[], offset=0]) -> buffer
|
||
|
|
|
||
|
|
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.
|
||
|
|
|
||
|
|
`varint.encode.bytes` will now be set to the number of bytes
|
||
|
|
modified.
|
||
|
|
|
||
|
|
### varint.decode(data[, offset=0]) -> number
|
||
|
|
|
||
|
|
decodes `data`, which can be either a buffer or array of integers, from position `offset` or default 0 and returns the decoded original integer.
|
||
|
|
|
||
|
|
Throws a `RangeError` when `data` does not represent a valid encoding.
|
||
|
|
|
||
|
|
### varint.decode.bytes
|
||
|
|
|
||
|
|
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.
|
||
|
|
|
||
|
|
### varint.encode.bytes
|
||
|
|
|
||
|
|
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.
|
||
|
|
|
||
|
|
|
||
|
|
### varint.encodingLength(num)
|
||
|
|
|
||
|
|
returns the number of bytes this number will be encoded as, up to a maximum of 8.
|
||
|
|
|
||
|
|
## usage notes
|
||
|
|
|
||
|
|
If varint is passed a buffer that does not contain a valid end
|
||
|
|
byte, then `decode` will throw `RangeError`, and `decode.bytes`
|
||
|
|
will be set to 0. If you are reading from a streaming source,
|
||
|
|
it's okay to pass an incomplete buffer into `decode`, detect this
|
||
|
|
case, and then concatenate the next buffer.
|
||
|
|
|
||
|
|
# License
|
||
|
|
|
||
|
|
MIT
|