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DimaRU/CDRCodable 1.2.1
An OMG Common Data Representation (CDR) encoder and decoder for Swift `Codable` types.
⭐️ 2
🕓 1 week ago
.package(url: "https://github.com/DimaRU/CDRCodable.git", from: "1.2.1")



A OMG Common Data Representation (CDR) (PLAIN_CDR) encoder and decoder for Swift Codable types.

Now can be used with FastRTPSSwift, a Swift wrapper for eProsima FastDDS library.

Use msg2swift to automatically generate Swift models from ROS .msg files.


  • Swift 5.8+


Encoding Messages

import CDRCodable

let encoder = CDREncoder()
let value = try! encoder.encode("hello")
// Data([6, 0, 0, 0, 0x68, 0x65, 0x6C, 0x6C, 0x6F, 0, 0, 0])

Decoding Messages

import CDRCodable

let decoder = CDRDecoder()
let data = Data([3, 0, 0, 0, 1, 0, 2, 0, 3, 0])
let value = try! decoder.decode([Int16].self, from: data)
// [1, 2, 3]


Swift Package Manager

Add the CDRCodable package to your target dependencies in Package.swift:

.package(url: "https://github.com/DimaRU/CDRCodable", from: "1.0.0"),

Supported IDL/ROS types

1. Primitive types

The following table shows the basic IDL types supported by CDRCodable and how they are mapped to Swift and C++11.

Swift C++11 ROS IDL
Int8 char int8 char
UInt8 uint8_t uint8 octet
Int16 int16_t int16 short
UInt16 uint16_t uint16 unsigned short
Int32 int32_t int32 long
UInt32 uint32_t uint32 unsigned long
Int64 int64_t int64 long long
UInt64 uint64_t uint64 unsigned long long
Float float float32 float
Double double float64 double
Bool bool bool boolean
String std::string string string

2. Arrays

Starting from version 1.1.1 CDRCodable supports fixed-size arrays. The high 16 bits of CodingKeys are used for this purpose. Declare CodingKeys as Int and write in the high 16 bits the required array size and property must be declared as Array. The lower 16 bits are not used. Note: Be careful when numbering CodingKeys! Use msg2swift to create CodingKeys automatically. Sample CodingKeys declaration for sensor_msgs/CameraInfo:

// CameraInfo.swift
// This file was generated from ROS message file using msg2swift.

struct CameraInfo: Codable {
    let header: Header
    let height: UInt32
    let width: UInt32
    let distortionModel: String
    let d: [Double]
    let k: [Double]
    let r: [Double]
    let p: [Double]
    let binningX: UInt32
    let binningY: UInt32
    let roi: RegionOfInterest

    enum CodingKeys: Int, CodingKey {
        case header = 1
        case height = 2
        case width = 3
        case distortionModel = 4
        case d = 5
        case k = 0x90006
        case r = 0x90007
        case p = 0xc0008
        case binningX = 9
        case binningY = 10
        case roi = 11

3. Sequences

CDRCodable supports sequences, which map between Swift Array and C++ std::vector container. The following table represents how the map between Swift, C++11 and IDL and is handled.

Swift C++11 IDL
Data std::vector<uint8_t> sequence<octet>
Array<Int8> std::vector<char> sequence<char>
Array<UInt8> std::vector<uint8_t> sequence<octet>
Array<Int16> std::vector<int16_t> sequence<short>
Array<UInt16> std::vector<uint16_t> sequence<unsigned short>
Array<Int32> std::vector<int32_t> sequence<long>
Array<UInt32> std::vector<uint32_t> sequence<unsigned long>
Array<Int64> std::vector<int64_t> sequence<long long>
Array<UInt64> std::vector<uint64_t> sequence<unsigned long long>
Array<Float> std::vector<float> sequence<float>
Array<Double> std::vector<double> sequence<double>
Array<Bool> std::vector<bool> sequence<boolean>
Array<String> std::vector<std::string> sequence<string>

4. Enumerations

Swift IDL
enum e: Int32 enum e

Example: IDL definition:

enum ESubsystemState
    UNKNOWN         = 0,
    INITIALIZED     = 1,
    POSTING         = 2,
    ACTIVE          = 3,
    STANDBY         = 4,
    RECOVERY        = 5,
    DISABLED        = 6


enum ESubsystemState: Int32, Codable {
    case unknown         = 0
    case initialized     = 1
    case posting         = 2
    case active          = 3
    case standby         = 4
    case recovery        = 5
    case disabled        = 6

5. Union

Union type is not supported by CDRCodable directly and needed custom coding. Example:

IDL definition:

union ControlUnion switch (unsigned long)
    case CONTROL_TYPE_S8:
        char value_int8;
    case CONTROL_TYPE_S16:
        short value_int16;
    case CONTROL_TYPE_S32:
        long value_int32;
    case CONTROL_TYPE_S64:
        long long value_int64;
    case CONTROL_TYPE_U8:
        octet value_uint8;
    case CONTROL_TYPE_U16:
        unsigned short value_uint16;
    case CONTROL_TYPE_U32:
        unsigned long value_uint32;
    case CONTROL_TYPE_U64:
        unsigned long long value_uint64;
        unsigned long value_bitmask;
        boolean value_button;
        boolean value_boolean;
        string<128> value_string;
        unsigned long value_string_menu;
        unsigned long value_int_menu;


enum ControlUnion: UInt32, Codable {
    case S8(value: Int8) = 0
    case S16(value: Int16)
    case S32(value: Int32)
    case S64(value: Int64)
    case U8(value: UInt8)
    case U16(value: UInt16)
    case U32(value: UInt32)
    case U64(value: UInt64)
    case Bitmask(bitmask: UInt32)
    case Button(button: Bool)
    case Boolean(value: Bool)
    case StringValue(value: String)
    case StringMenu(stringMenu: UInt32)
    case IntMenu(intMenu: UInt32)
    init(from decoder: Decoder) throws {
        var container = try decoder.singleValueContainer()
        let selector = try container.decode(UInt32.self)
        switch selector {
            case 0:
                let value = try container.decode(Int8.self)
                self = .S8(value: value)
            case 1:
                let value = try container.decode(Int16.self)
                self = .S16(value: value)
            case 2:
                let value = try container.decode(Int32.self)
                self = .S32(value: value)
            case 3:
                let value = try container.decode(Int64.self)
                self = .S64(value: value)
            case 4:
                let value = try container.decode(UInt8.self)
                self = .U8(value: value)
            case 5:
                let value = try container.decode(UInt16.self)
                self = .U16(value: value)
            case 6:
                let value = try container.decode(UInt32.self)
                self = .U32(value: value)
            case 7:
                let value = try container.decode(UInt64.self)
                self = .U64(value: value)
            case 8:
                let value = try container.decode(UInt32.self)
                self = .Bitmask(bitmask: value)
            case 9:
                let value = try container.decode(Bool.self)
                self = .Button(button: value)
            case 10:
                let value = try container.decode(Bool.self)
                self = .Boolean(value: value)
            case 11:
                let value = try container.decode(String.self)
                self = .StringValue(value: value)
            case 12:
                let value = try container.decode(UInt32.self)
                self = .StringMenu(stringMenu: value)
            case 13:
                let value = try container.decode(UInt32.self)
                self = .IntMenu(intMenu: value)
                let error = DecodingError.dataCorruptedError(in: container, debugDescription: "Illegal union selector \(selector)")
                throw error
    func encode(to encoder: Encoder) throws {
        var container = encoder.singleValueContainer()
        try container.encode(self.rawValue)
        switch self {
        case .S8(value: let value): try container.encode(value)
        case .S16(value: let value): try container.encode(value)
        case .S32(value: let value): try container.encode(value)
        case .S64(value: let value): try container.encode(value)
        case .U8(value: let value): try container.encode(value)
        case .U16(value: let value): try container.encode(value)
        case .U32(value: let value): try container.encode(value)
        case .U64(value: let value): try container.encode(value)
        case .Bitmask(bitmask: let bitmask): try container.encode(bitmask)
        case .Button(button: let button): try container.encode(button)
        case .Boolean(value: let value): try container.encode(value)
        case .StringValue(value: let value): try container.encode(value)
        case .StringMenu(stringMenu: let stringMenu): try container.encode(stringMenu)
        case .IntMenu(intMenu: let intMenu): try container.encode(intMenu)

6. Struct

struct may be coded as Swift struct or class. Example:

IDL definition:

struct ControlTarget
    string id;
    float pitch;
    float yaw;
    float thrust;
    float lift;
struct ControlTarget: Codable
    let id: String

    let pitch: Float
    let yaw: Float
    let thrust: Float
    let lift: Float




Stars: 2
Last commit: 1 week ago
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Release Notes

1 week ago

Msg2swift SPM command plugin.

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