wirebit

Header-only C++ library for simulating hardware communication interfaces over shared memory, with bridges to real Linux interfaces.

Development Status

Current version: 0.0.9 (January 5, 2026)

See CHANGELOG.md for version history and recent changes.

Overview

Wirebit provides a unified framework for simulating serial (UART/RS232), CAN bus, and Ethernet communication interfaces in software. It enables multi-process testing of embedded systems without requiring physical hardware, making it ideal for robotics development, automotive testing, and industrial automation scenarios.

Communication happens over shared memory using lock-free SPSC ring buffers with sub-microsecond latency. The library supports configurable network impairments (latency, jitter, packet loss, corruption, duplication) with deterministic pseudo-random number generation for reproducible simulations.

The library also supports bridging to real Linux interfaces: PTY for serial devices, SocketCAN for CAN bus, TAP for L2 Ethernet, and TUN for L3 IP packets. This allows seamless transition from pure simulation to hardware-in-the-loop testing without changing your application code.

Key design principles:

Header-only architecture: No compilation required, just #include <wirebit/wirebit.hpp>
Zero-copy communication: Shared memory ring buffers with atomic operations only
Type-safe error handling: Uses datapod::Result<T, E> for errors, no exceptions in hot path
Deterministic simulation: Seeded PRNG ensures reproducible test scenarios
Hardware-ready: Conditional compilation for real interface bridging
Multi-process IPC: Share communication channels between processes without network overhead

Architecture Diagrams

Component Architecture:

┌─────────────────────────────────────────────────────────────────────────────────┐
│                              WIREBIT LIBRARY                                     │
├──────────────────┬──────────────────┬──────────────────┬────────────────────────┤
│  SerialEndpoint  │   CanEndpoint    │  EthEndpoint     │      LinkModel         │
│  (Baud pacing)   │  (SocketCAN API) │  (L2 frames)     │     (Impairments)      │
│                  │                  │                  │                        │
│  ┌────────────┐  │  ┌────────────┐  │  ┌────────────┐  │  ┌──────────────────┐  │
│  │ 9600-921k  │  │  │ Std/Ext ID │  │  │ MAC filter │  │  │ Latency/Jitter   │  │
│  │ Data/Stop  │  │  │ RTR frames │  │  │ Bandwidth  │  │  │ Drop/Corrupt     │  │
│  │ Parity     │  │  │ Bit timing │  │  │ Promiscuous│  │  │ Deterministic    │  │
│  └────────────┘  │  └────────────┘  │  └────────────┘  │  └──────────────────┘  │
├──────────────────┴──────────────────┴──────────────────┴────────────────────────┤
│                           Frame Layer (44-byte header)                           │
│                    [Magic|Version|Type|Timestamps|IDs|Payload]                   │
├──────────────────┬──────────────────┬──────────────────┬───────────┬────────────┤
│    ShmLink       │    PtyLink       │  SocketCanLink   │  TapLink  │  TunLink   │
│  (Simulation)    │  (Serial PTY)    │  (CAN vcan/can)  │ (L2 Eth)  │  (L3 IP)   │
│                  │                  │                  │           │            │
│  ┌────────────┐  │  ┌────────────┐  │  ┌────────────┐  │ ┌───────┐ │ ┌────────┐ │
│  │ SPSC Ring  │  │  │ /dev/pts/X │  │  │ vcan/can0  │  │ │ tap0  │ │ │ tun0   │ │
│  │ <1µs lat   │  │  │ Symlink    │  │  │ Auto-setup │  │ │ L2    │ │ │ L3     │ │
│  │ Zero-copy  │  │  │ Non-block  │  │  │ Sudoers    │  │ │ Raw   │ │ │ ICMP   │ │
│  └────────────┘  │  └────────────┘  │  └────────────┘  │ └───────┘ │ └────────┘ │
├──────────────────┼──────────────────┼──────────────────┼───────────┼────────────┤
│  Shared Memory   │   /dev/pts/X     │  vcan/can iface  │    TAP    │    TUN     │
│  (Multi-proc)    │  (Serial tools)  │  (CAN tools)     │ (tcpdump) │  (ping)    │
└──────────────────┴──────────────────┴──────────────────┴───────────┴────────────┘
       │                   │                   │               │            │
       └───────────────────┴───────────────────┴───────────────┴────────────┘
                                        │
                                ┌───────▼────────┐
                                │  Your App/Lib  │
                                │  (Multi-proc)  │
                                └────────────────┘

Data Flow Example (CAN Bus Simulation):

Process A                     Shared Memory                    Process B
┌──────────┐                 ┌──────────────┐                 ┌──────────┐
│CanEndpoint│                │   ShmLink    │                 │CanEndpoint│
│  (Node 1) │                │              │                 │  (Node 2) │
│           │                │  ┌────────┐  │                 │           │
│  send()   ├───Frame────────┼─►│ Ring A │──┼────Frame────────┤  recv()   │
│           │                │  └────────┘  │                 │           │
│           │                │              │                 │           │
│  recv()   │◄───Frame───────┼──│ Ring B │◄─┼────Frame────────┤  send()   │
│           │                │  └────────┘  │                 │           │
└──────────┘                 │              │                 └──────────┘
                             │  LinkModel   │
                             │  ┌────────┐  │
                             │  │Latency │  │ (Applied to both directions)
                             │  │Jitter  │  │
                             │  │Drop    │  │
                             │  └────────┘  │
                             └──────────────┘

Installation

Quick Start (CMake FetchContent)

include(FetchContent)
FetchContent_Declare(
  wirebit
  GIT_REPOSITORY https://github.com/robolibs/wirebit
  GIT_TAG main
)
FetchContent_MakeAvailable(wirebit)

target_link_libraries(your_target PRIVATE wirebit)

Recommended: XMake

XMake is a modern, fast, and cross-platform build system.

Install XMake:

curl -fsSL https://xmake.io/shget.text | bash

Add to your xmake.lua:

add_requires("wirebit")

target("your_target")
    set_kind("binary")
    add_packages("wirebit")
    add_files("src/*.cpp")

Build:

xmake
xmake run

Complete Development Environment (Nix + Direnv + Devbox)

For the ultimate reproducible development environment:

1. Install Nix (package manager from NixOS):

# Determinate Nix Installer (recommended)
curl --proto '=https' --tlsv1.2 -sSf -L https://install.determinate.systems/nix | sh -s -- install

Nix - Reproducible, declarative package management

2. Install direnv (automatic environment switching):

sudo apt install direnv

# Add to your shell (~/.bashrc or ~/.zshrc):
eval "$(direnv hook bash)"  # or zsh

direnv - Load environment variables based on directory

3. Install Devbox (Nix-powered development environments):

curl -fsSL https://get.jetpack.io/devbox | bash

Devbox - Portable, isolated dev environments

4. Use the environment:

cd wirebit
direnv allow  # Allow .envrc (one-time)
# Environment automatically loaded! All dependencies available.

xmake        # or cmake, make, etc.

Usage

Basic Usage - Serial Communication

#include <wirebit/wirebit.hpp>
using namespace wirebit;

// Create shared memory link (64KB buffer)
auto link = ShmLink::create(String("serial"), 64 * 1024).value();

// Configure serial endpoint (115200 baud, 8N1)
SerialConfig config{
    .baud = 115200,
    .data_bits = 8,
    .stop_bits = 1,
    .parity = 'N'
};

// Create endpoint with ID=1
SerialEndpoint serial(std::make_shared<ShmLink>(std::move(link)), config, 1);

// Send data (realistic byte-by-byte timing)
Bytes data = {0x48, 0x65, 0x6C, 0x6C, 0x6F};  // "Hello"
serial.send(data);

// Receive data
serial.process();  // Process incoming frames
auto result = serial.recv();
if (result.is_ok()) {
    Bytes received = result.value();
    // Process received data
}

Basic Usage - CAN Bus

// Create shared memory link (64KB buffer)
auto link = ShmLink::create(String("can"), 64 * 1024).value();

// Configure CAN endpoint (500 kbps)
CanConfig config{.bitrate = 500000};
CanEndpoint can(std::make_shared<ShmLink>(std::move(link)), config, 1);

// Send standard CAN frame
can_frame frame;
frame.can_id = 0x123;
frame.can_dlc = 4;
std::memcpy(frame.data, "\xDE\xAD\xBE\xEF", 4);
can.send_can(frame);

// Receive CAN frames
can.process();
auto result = can.recv_can();
if (result.is_ok()) {
    can_frame received = result.value();
    // Process CAN frame
}

Basic Usage - Ethernet L2

// Create shared memory link (1MB buffer)
auto link = ShmLink::create(String("eth"), 1024 * 1024).value();

// Configure Ethernet endpoint (1 Gbps)
MacAddr mac = {0x02, 0x00, 0x00, 0x00, 0x00, 0x01};
EthConfig config{.bandwidth_bps = 1000000000};
EthEndpoint eth(std::make_shared<ShmLink>(std::move(link)), config, 1, mac);

// Send Ethernet frame
Bytes payload = {0x01, 0x02, 0x03, 0x04};
Bytes frame = make_eth_frame(MAC_BROADCAST, mac, ETH_P_IP, payload);
eth.send_eth(frame);

// Receive Ethernet frames
eth.process();
auto result = eth.recv_eth();
if (result.is_ok()) {
    Bytes received = result.value();
    // Parse and process Ethernet frame
}

Advanced Usage - Network Impairment Simulation

// Configure realistic network conditions
LinkModel model{
    .base_latency_ns = 1000000,   // 1 ms base latency
    .jitter_ns = 200000,          // ±200 µs jitter
    .drop_prob = 0.05,            // 5% packet loss
    .duplicate_prob = 0.01,       // 1% duplication
    .corrupt_prob = 0.01,         // 1% corruption (bit flips)
    .bandwidth_bps = 1000000,     // 1 Mbps bandwidth limit
    .seed = 12345                 // Deterministic seed for reproducibility
};

// Create link with impairment model
auto link = ShmLink::create(String("impaired"), 64 * 1024, &model).value();

// All communication through this link will experience the configured impairments
// Perfect for testing error handling, retransmission logic, and timeout behavior

Advanced Usage - Multi-Process Communication

// Process A (Creator)
auto link_a = ShmLink::create(String("ipc_channel"), 64 * 1024).value();
SerialEndpoint serial_a(std::make_shared<ShmLink>(std::move(link_a)), config, 1);

// Process B (Attacher)
auto link_b = ShmLink::attach(String("ipc_channel")).value();
SerialEndpoint serial_b(std::make_shared<ShmLink>(std::move(link_b)), config, 2);

// Now both processes can communicate bidirectionally
// Process A sends to Process B
serial_a.send(data);

// Process B receives from Process A
serial_b.process();
auto result = serial_b.recv();

Hardware Links (Linux)

Build with hardware support enabled (default since v0.0.9):

make reconfig && make build

To disable hardware support (simulation only):

NO_HARDWARE=1 make reconfig && NO_HARDWARE=1 make build

PtyLink - Serial Bridge

Bridge to Linux pseudo-terminal devices for integration with real serial tools:

#include <wirebit/serial/pty_link.hpp>

PtyConfig config{
    .create_symlink = true,
    .symlink_path = "/tmp/serial"
};

auto pty = PtyLink::create(config).value();
SerialEndpoint serial(std::make_shared<PtyLink>(std::move(pty)), serial_config, 1);

// Now connect with: screen /tmp/serial 115200
// Or: minicom -D /tmp/serial
// Or: picocom /tmp/serial -b 115200

SocketCanLink - CAN Bridge

Bridge to Linux SocketCAN interfaces for integration with real CAN tools:

#include <wirebit/can/socketcan_link.hpp>

SocketCanConfig config{
    .interface_name = "vcan0",
    .create_if_missing = true,
    .destroy_on_close = true
};

auto can_link = SocketCanLink::create(config).value();
CanEndpoint can(std::make_shared<SocketCanLink>(std::move(can_link)), can_config, 1);

// Monitor with: candump vcan0
// Send with: cansend vcan0 123#DEADBEEF

TapLink - L2 Ethernet Bridge

Bridge to Linux TAP devices for L2 Ethernet frame injection:

#include <wirebit/eth/tap_link.hpp>

TapConfig config{
    .interface_name = "tap0",
    .create_if_missing = true,
    .destroy_on_close = true,
    .owner_uid = getuid()
};

auto tap = TapLink::create(config).value();
EthEndpoint eth(std::make_shared<TapLink>(std::move(tap)), eth_config, 1, mac);

// Monitor with: sudo tcpdump -i tap0 -e -n
// Or: sudo wireshark -i tap0

TunLink - L3 IP Bridge

Bridge to Linux TUN devices for L3 IP packet injection with ICMP responder:

#include <wirebit/eth/tun_link.hpp>

TunConfig config{
    .interface_name = "tun0",
    .ip_address = "10.100.0.1/24",
    .create_if_missing = true,
    .destroy_on_close = true,
    .owner_uid = getuid()
};

auto tun = TunLink::create(config).value();

// Test with: ping 10.100.0.2 (your app responds to ICMP)
// Monitor with: sudo tcpdump -i tun0 -n

Sudoers setup (optional, for passwordless interface creation):

# /etc/sudoers.d/wirebit
%wheel ALL=(ALL) NOPASSWD: /usr/bin/ip link add dev vcan* type vcan
%wheel ALL=(ALL) NOPASSWD: /usr/bin/ip link set vcan* up
%wheel ALL=(ALL) NOPASSWD: /usr/bin/ip link delete vcan*
%wheel ALL=(ALL) NOPASSWD: /usr/bin/ip tuntap add dev tap* mode tap user *
%wheel ALL=(ALL) NOPASSWD: /usr/bin/ip tuntap add dev tun* mode tun user *
%wheel ALL=(ALL) NOPASSWD: /usr/bin/ip link set tap* up
%wheel ALL=(ALL) NOPASSWD: /usr/bin/ip link set tun* up
%wheel ALL=(ALL) NOPASSWD: /usr/bin/ip addr add * dev tun*
%wheel ALL=(ALL) NOPASSWD: /usr/bin/ip link delete tap*
%wheel ALL=(ALL) NOPASSWD: /usr/bin/ip link delete tun*

Features

Serial Endpoint (UART/RS232) - Configurable baud rates (9600-921600 bps), data bits (5-8), stop bits (1-2), parity (None/Even/Odd). Realistic byte-by-byte transmission timing with buffered reading.
```
SerialConfig config{.baud = 115200, .data_bits = 8, .stop_bits = 1, .parity = 'N'};
```
CAN Endpoint (SocketCAN-compatible) - Standard (11-bit) and Extended (29-bit) IDs, RTR frames, configurable bitrates (125 kbps - 1 Mbps). Automatic frame timing with bit stuffing overhead. Broadcast nature simulation.
```
CanConfig config{.bitrate = 500000};
auto frame = CanEndpoint::make_std_frame(0x123, data, 4);
```
Ethernet Endpoint (L2 Network) - Raw L2 frame handling, MAC address filtering, configurable bandwidth (10 Mbps - 1 Gbps+), EtherType support (IPv4/IPv6/ARP/VLAN), promiscuous mode, automatic padding to minimum frame size (60 bytes).
```
EthConfig config{.bandwidth_bps = 1000000000};  // 1 Gbps
```
Hardware Links (Linux) - PTY for serial tools (minicom, screen), SocketCAN for CAN tools (candump, cansend), TAP for L2 Ethernet (tcpdump, wireshark), TUN for L3 IP (ping, traceroute). Automatic interface creation and cleanup.
Shared Memory Transport - Lock-free SPSC ring buffers, sub-microsecond latency (<1µs), zero syscalls in hot path (atomic operations only), configurable buffer sizes (64KB - 1MB typical), bidirectional communication.
Network Simulation (LinkModel) - Configurable latency, jitter (uniform random), packet loss, duplication, corruption (bit flips), bandwidth limiting. Deterministic PRNG with seed for reproducible test scenarios.
```
LinkModel model{.base_latency_ns = 1000000, .jitter_ns = 200000, .drop_prob = 0.05, .seed = 42};
```
Type-Safe Error Handling - Uses datapod::Result<T, E> for all fallible operations. No exceptions in hot path. Clear error types for debugging.
Multi-Process IPC - Share communication channels between processes using shared memory. Creator/attacher pattern with automatic cleanup.

Performance

Wirebit is designed for high-performance simulation with minimal overhead:

Hot path latency: <1µs for ShmLink push/pop operations
Zero syscalls: Hot path uses only atomic operations (no kernel involvement)
Lock-free: SPSC ring buffers per direction, no mutex contention
Memory efficiency: Configurable ring buffers (64KB - 1MB typical)
Threading model: SPSC per direction, safe for concurrent access
Frame overhead: 44-byte header per frame (magic, version, type, timestamps, IDs, length)

Benchmark results (typical x86_64 system):

Serial endpoint: Accurate baud rate pacing within 1% of target
CAN endpoint: Frame timing includes bit stuffing overhead
Ethernet endpoint: Bandwidth shaping accurate to within 5% of target
ShmLink: 500K+ frames/sec throughput per direction

Examples

The examples/ directory contains comprehensive demonstrations:

./build/serial_demo         # Serial communication scenarios (baud rates, parity)
./build/can_demo            # CAN bus examples (std/ext frames, RTR)
./build/ethernet_demo       # Ethernet L2 examples (MAC filtering, bandwidth)
./build/can_bus_hub         # Multi-node CAN hub simulation
./build/pty_demo            # PTY bridge demo (connect with screen/minicom)
./build/socketcan_demo      # SocketCAN bridge (requires hardware support)
./build/tap_demo            # TAP L2 bridge (requires hardware support)
./build/tun_demo            # TUN L3 bridge with ICMP responder (requires hardware support)
./build/link_model_demo     # Network impairment demonstration
./build/multi_process_demo  # Multi-process IPC example

Run examples:

make build
./build/serial_demo

Testing

Wirebit includes comprehensive test coverage:

make build                    # Build (hardware support enabled by default)
NO_HARDWARE=1 make build      # Build simulation-only
make test                     # Run all tests
make test TEST=test_tap_link  # Run specific test

Test Coverage:

17 test suites
200+ assertions
Unit tests: Frame encoding/decoding, link model behavior, ring buffer operations
Integration tests: Serial timing accuracy, CAN broadcast, Ethernet bandwidth shaping
Hardware tests: PTY/SocketCAN/TAP/TUN interface verification via ip link
Multi-process tests: IPC communication scenarios

Roadmap

v0.1 - SHM backend with Serial/CAN/Ethernet endpoints ✅
v0.2 - PTY backend for serial bridging ✅
v0.3 - SocketCAN backend for CAN bridging ✅
v0.6 - TAP backend for L2 Ethernet bridging ✅
v0.7 - TUN backend for L3 IP bridging ✅
v0.8 - Performance optimizations and benchmarking (in progress)
v0.9 - Additional protocol support (SPI, I2C)
v1.0 - Stable API, production-ready

Dependencies

Required:

datapod (v0.0.29+) - POD-friendly data structures (Result, Error, Vector, String, RingBuffer, Stamp)
echo (main) - Logging with color support
C++20 - Modern C++ features (concepts, ranges, modules)

Optional (for examples):

rerun_sdk - Visualization (via pkg-config)
optinum (v0.0.16) - Optimization utilities
graphix (v0.0.6) - Graphics utilities

Testing:

doctest (v2.4.12) - Unit testing framework

System Requirements (for hardware links):

Linux with /dev/net/tun support
sudo or sudoers configuration for interface creation
SocketCAN kernel module (vcan)

License

MIT License - see LICENSE for details.

Acknowledgments

Made possible thanks to these amazing projects.

Name		Name	Last commit message	Last commit date
Latest commit History 81 Commits
examples		examples
include/wirebit		include/wirebit
misc/sudoers.d		misc/sudoers.d
test		test
.clang-format		.clang-format
.envrc		.envrc
.gitignore		.gitignore
ACKNOWLEDGMENTS.md		ACKNOWLEDGMENTS.md
CHANGELOG.md		CHANGELOG.md
CMakeLists.txt		CMakeLists.txt
Makefile		Makefile
PROJECT		PROJECT
README.md		README.md
cliff.toml		cliff.toml
devbox.json		devbox.json

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wirebit

Development Status

Overview

Architecture Diagrams

Installation

Quick Start (CMake FetchContent)

Recommended: XMake

Complete Development Environment (Nix + Direnv + Devbox)

Usage

Basic Usage - Serial Communication

Basic Usage - CAN Bus

Basic Usage - Ethernet L2

Advanced Usage - Network Impairment Simulation

Advanced Usage - Multi-Process Communication

Hardware Links (Linux)

PtyLink - Serial Bridge

SocketCanLink - CAN Bridge

TapLink - L2 Ethernet Bridge

TunLink - L3 IP Bridge

Features

Performance

Examples

Testing

Roadmap

Dependencies

License

Acknowledgments

About

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Releases 12

Packages

Languages

robolibs/wirebit

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Repository files navigation

wirebit

Development Status

Overview

Architecture Diagrams

Installation

Quick Start (CMake FetchContent)

Recommended: XMake

Complete Development Environment (Nix + Direnv + Devbox)

Usage

Basic Usage - Serial Communication

Basic Usage - CAN Bus

Basic Usage - Ethernet L2

Advanced Usage - Network Impairment Simulation

Advanced Usage - Multi-Process Communication

Hardware Links (Linux)

PtyLink - Serial Bridge

SocketCanLink - CAN Bridge

TapLink - L2 Ethernet Bridge

TunLink - L3 IP Bridge

Features

Performance

Examples

Testing

Roadmap

Dependencies

License

Acknowledgments

About

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