227 lines
7.2 KiB
Markdown
227 lines
7.2 KiB
Markdown
<p align="center">
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<img src="images/logo.png" alt="arpack logo" width="240">
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</p>
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# ArPack
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Binary serialization code generator for Go, C#, and TypeScript. Define messages once as Go structs — get zero-allocation `Marshal`/`Unmarshal` for Go, `unsafe` pointer-based `Serialize`/`Deserialize` for C#, and `DataView`-based serialization for TypeScript/browser.
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## Features
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- **Single source of truth** — define messages in Go, generate code for Go, C#, and TypeScript
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- **Float quantization** — compress `float32`/`float64` to 8 or 16 bits with a `pack` struct tag
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- **Boolean packing** — consecutive `bool` fields are packed into single bytes (up to 8 per byte)
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- **Enums** — `type Opcode uint16` + `const` block becomes C#/TypeScript enums
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- **Nested types, fixed arrays, slices** — full support for complex message structures
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- **Cross-language binary compatibility** — Go, C#, and TypeScript produce identical wire formats
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- **Browser support** — TypeScript target uses native DataView API for zero-dependency serialization
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## When to use
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ArPack is designed for real-time multiplayer games and other latency-sensitive systems where a Go backend talks to a C# client over a binary protocol.
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Typical setups:
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- **[Nakama](https://heroiclabs.com/nakama/) + Unity** — define all network messages in Go, generate C# structs for Unity. Both sides share the exact same wire format with no reflection or boxing.
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- **Custom Go game server + Unity** — roll your own server without pulling in a serialization framework. ArPack generates plain `Marshal`/`Unmarshal` methods with zero allocations on the hot path.
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- **Any Go service + .NET client** — works anywhere you control both ends and want a compact binary protocol without Protobuf's runtime overhead or code-gen complexity.
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- **Go backend + Browser/WebSocket** — generate TypeScript classes for browser-based clients. Uses native DataView API with zero dependencies.
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## Installation
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```bash
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go install github.com/edmand46/arpack/cmd/arpack@latest
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```
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## Usage
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```bash
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# Generate Go + C# + TypeScript
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arpack -in messages.go -out-go ./gen -out-cs ../Unity/Assets/Scripts -out-ts ./web/src/messages
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# Generate only TypeScript
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arpack -in messages.go -out-ts ./web/src/messages
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```
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| Flag | Description |
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|---|---|
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| `-in` | Input Go file with struct definitions (required) |
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| `-out-go` | Output directory for generated Go code |
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| `-out-cs` | Output directory for generated C# code |
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| `-out-ts` | Output directory for generated TypeScript code |
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| `-cs-namespace` | C# namespace (default: `Arpack.Messages`) |
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**Output files:**
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- Go: `{name}_gen.go`
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- C#: `{Name}.gen.cs`
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- TypeScript: `{Name}.gen.ts`
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## Schema Definition
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Messages are defined as Go structs in a single `.go` file:
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```go
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package messages
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// Quantized 3D vector — 6 bytes instead of 12
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type Vector3 struct {
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X float32 `pack:"min=-500,max=500,bits=16"`
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Y float32 `pack:"min=-500,max=500,bits=16"`
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Z float32 `pack:"min=-500,max=500,bits=16"`
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}
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// Enum
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type Opcode uint16
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const (
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OpcodeUnknown Opcode = iota
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OpcodeAuthorize
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OpcodeJoinRoom
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)
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type MoveMessage struct {
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Position Vector3 // nested type
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Velocity [3]float32 // fixed-length array
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Waypoints []Vector3 // variable-length slice
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PlayerID uint32
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Active bool // 3 consecutive bools →
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Visible bool // packed into 1 byte
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Ghost bool
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Name string
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}
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```
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### Supported Types
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| Type | Wire Size |
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|---|---|
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| `bool` (packed) | 1 bit (up to 8 per byte) |
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| `int8`, `uint8` | 1 byte |
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| `int16`, `uint16` | 2 bytes |
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| `int32`, `uint32`, `float32` | 4 bytes |
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| `int64`, `uint64`, `float64` | 8 bytes |
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| `string` | 2-byte length prefix + UTF-8 |
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| `[N]T` | N × sizeof(T) |
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| `[]T` | 2-byte length prefix + N × sizeof(T) |
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### Float Quantization
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Use the `pack` struct tag to compress floats:
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```go
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X float32 `pack:"min=-500,max=500,bits=16"` // 2 bytes instead of 4
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Y float32 `pack:"min=0,max=1,bits=8"` // 1 byte instead of 4
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```
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| Parameter | Description |
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|---|---|
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| `min` | Minimum expected value |
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| `max` | Maximum expected value |
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| `bits` | Target size: `8` (uint8) or `16` (uint16) |
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Values are linearly mapped: `encoded = (value - min) / (max - min) * maxUint`.
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## Generated Code
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### Go
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```go
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func (m *MoveMessage) Marshal(buf []byte) []byte
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func (m *MoveMessage) Unmarshal(data []byte) (int, error)
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```
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`Marshal` appends to the buffer and returns it. `Unmarshal` reads from the buffer and returns bytes consumed.
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### C#
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```csharp
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public unsafe int Serialize(byte* buffer)
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public static unsafe int Deserialize(byte* buffer, out MoveMessage msg)
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```
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Uses unsafe pointers for zero-copy serialization. Returns bytes written/consumed.
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### TypeScript
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```typescript
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export class MoveMessage {
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position: Vector3 = new Vector3();
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velocity: number[] = new Array<number>(3).fill(0);
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waypoints: Vector3[] = [];
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playerId: number = 0;
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active: boolean = false;
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visible: boolean = false;
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ghost: boolean = false;
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name: string = "";
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serialize(view: DataView, offset: number): number
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static deserialize(view: DataView, offset: number): [MoveMessage, number]
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}
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```
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Uses native DataView API for browser-compatible serialization with zero dependencies. Returns bytes written/consumed.
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**Note:** TypeScript field names are converted to camelCase (e.g., `PlayerID` → `playerId`).
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## Wire Format
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- Little-endian byte order
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- No message framing — fields are written in declaration order
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- Variable-length fields (`string`, `[]T`) prefixed with `uint16` length
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- Booleans packed as bitfields (LSB first, up to 8 per byte)
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- Quantized floats stored as `uint8` or `uint16`
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## Benchmarks
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### Go Results (M3 Max)
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```
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BenchmarkArPack_Marshal-16 382568360 9.5 ns/op 5065 MB/s 0 B/op 0 allocs/op
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BenchmarkArPack_Unmarshal-16 98895892 34.6 ns/op 1388 MB/s 40 B/op 2 allocs/op
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BenchmarkProto_Marshal-16 21989466 163.6 ns/op 416 MB/s 0 B/op 0 allocs/op
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BenchmarkProto_Unmarshal-16 13950333 256.9 ns/op 265 MB/s 248 B/op 7 allocs/op
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BenchmarkFlatBuffers_Marshal-16 16297458 221.4 ns/op 687 MB/s 0 B/op 0 allocs/op
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BenchmarkFlatBuffers_Unmarshal-16 56095480 64.8 ns/op 2345 MB/s 24 B/op 1 allocs/op
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```
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| Format | Size |
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| ArPack | 48 bytes |
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| Protobuf | 68 bytes |
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| FlatBuffers | 152 bytes |
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```bash
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go test ./benchmarks/... -bench=. -benchmem
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```
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### Unity Mono (M3 Max)
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```
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ArPack Serialize: 96.7 ns/op | 0 B/op
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ArPack Deserialize: 205.4 ns/op | 0 B/op
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Proto Serialize (alloc): 930.2 ns/op | 0 B/op
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Proto Deserialize (alloc): 1621.2 ns/op | 29 B/op
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Proto Serialize (reuse): 652.7 ns/op | 0 B/op
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```
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ArPack serialize is ~10× faster than Protobuf in Unity. Protobuf deserialize allocates on every call — a GC pressure source in hot game loops. ArPack deserialize is zero-alloc.
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```bash
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make gen-unity
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# then attach BenchmarkRunner to any GameObject in SampleScene and press Play
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```
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## Running Tests
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```bash
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# Unit tests
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go test ./parser/... ./generator/...
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# End-to-end cross-language tests
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go test ./e2e/...
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```
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