Flatty - serializer and tools for flat binary blobs.

• atlas use flatty
• nimble install flatty

API reference

This library has no dependencies other than the Nim standard library.

About

• Aim of flatty is to be the fastest and simplest serializer/deserializer for Nim.
• Also includes hexprint to print out binary data.
• Also includes binny a simpler replacement for StringStream (no IO effects, operates on a string)
• Also includes hashy a hash for any objects based on the flatty serializer.
• Also includes encode a way to convert to/from utf16 BE/LE and with BOM and utf32.

Speed

Flatty aims to be fast. It achieves this by:

• Not using slowish StringStream.
• Checking if objects are "flat" and just copying them.
• Not doing anything extra like versioning, type checking, etc ...
• Liberal use of {.inline.}

Serialize speed

name ............................... min time      avg time    std dv   runs
treeform/flatty .................... 6.303 ms      6.514 ms    ±0.181   x100
bingod/planetis-m ................. 11.337 ms     12.688 ms    ±1.641   x100
disruptek/frosty .................. 14.767 ms     14.924 ms    ±0.122   x100
treeform/jsony .................... 12.989 ms     13.343 ms    ±0.408   x100

Deserialize speed

treeform/flatty ................... 10.526 ms     16.134 ms    ±5.508   x100
bingod/planetis-m binTo ........... 12.836 ms     17.993 ms    ±0.181   x100
disruptek/frosty .................. 38.513 ms     42.357 ms    ±0.535   x100
treeform/jsony .................... 96.830 ms    100.615 ms    ±0.992   x100

JavaScript

Flatty supports Nim's js mode. Some features like uint64/int64 are supported badly because of Nim's limitations. Serializing of non-Nim JavaScript objects is not supported.

Versioning

Note, unlike protobuf or thirft, flatty has no versioning mechanism, if structure of your objects changes the resulting binary would be changed and could not be read back again. Because the schema is just plain Nim types, you need to make sure changing them does not impact your ability to read old flatty binary blobs.

Compression

Flatty does not do compression it self but I recommend using the excellent https://github.com/guzba/supersnappy library to compress your flatty blobs before you send them over network or write them to disk. Snappy protocol is at this sweet spot of very fast compression, not the best but decent compression ratio, and very simple code.

Networking

The flatty + supersnappy + netty were originally made to be used together. Netty is a great for UDP networking for games.

API: flatty

import flatty

func toFlatty

Takes structures and turns them into binary string.

func toFlatty[T](x: T): string

func fromFlatty

Takes binary string and turn into structures.

func fromFlatty[T](s: string; x: typedesc[T]): T

API: flatty/hexprint

import flatty/hexprint

proc hexPrint

Prints a string in hex format of the old DOS debug program. Useful for looking at binary dumps.

hexPrint("Hi how are you doing today?")

0000:  48 69 20 68 6F 77 20 61-72 65 20 79 6F 75 20 64 Hi how are you d
0010:  6F 69 6E 67 20 74 6F 64-61 79 3F .. .. .. .. .. oing today?.....

proc hexPrint(buf: string): string

API: flatty/binny

import flatty/binny

func readUint8

func readUint8(s: string; i: int): uint8

func writeUint8

func writeUint8(s: var string; i: int; v: uint8)

func addUint8

func addUint8(s: var string; v: uint8)

func readUint16

func readUint16(s: string; i: int): uint16

func writeUint16

func writeUint16(s: var string; i: int; v: uint16)

func addUint16

func addUint16(s: var string; v: uint16)

func readUint32

func readUint32(s: string; i: int): uint32

func writeUint32

func writeUint32(s: var string; i: int; v: uint32)

func addUint32

func addUint32(s: var string; v: uint32)

func readUint64

func readUint64(s: string; i: int): uint64

func writeUint64

func writeUint64(s: var string; i: int; v: uint64)

func addUint64

func addUint64(s: var string; v: uint64)

func readInt8

func readInt8(s: string; i: int): int8

func writeInt8

func writeInt8(s: var string; i: int; v: int8)

func addInt8

func addInt8(s: var string; v: int8)

func readInt16

func readInt16(s: string; i: int): int16

func writeInt16

func writeInt16(s: var string; i: int; v: int16)

func addInt16

func addInt16(s: var string; i: int16)

func readInt32

func readInt32(s: string; i: int): int32

func writeInt32

func writeInt32(s: var string; i: int; v: int32)

func addInt32

func addInt32(s: var string; i: int32)

func readInt64

func readInt64(s: string; i: int): int64

func writeInt64

func writeInt64(s: var string; i: int; v: int64)

func addInt64

func addInt64(s: var string; i: int64)

func readFloat32

func readFloat32(s: string; i: int): float32

func addFloat32

func addFloat32(s: var string; v: float32)

func readFloat64

func readFloat64(s: string; i: int): float64

func addFloat64

func addFloat64(s: var string; v: float64)

func addStr

func addStr(s: var string; v: string)

func readStr

func readStr(s: string; i: int; v: int): string

func swap

func swap(v: uint8): uint8

func swap

func swap(v: uint16): uint16

func swap

func swap(v: uint32): uint32

func swap

func swap(v: uint64): uint64

func maybeSwap

func maybeSwap[T](v: T; enable: bool): T