🚀 CompOS

Zero-task allocation overhead and ultra-low context-switching scheduling for your projects.

Currently Project is written in C and Zig, however it will be transitioned to fully Zig once functionality is implemented for better performance.

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Table of Contents

1. Why Choose CompOS?
2. About Zig and C++
   • Benefits
   • Limitations
3. How to Use CompOS
   • Using with Zig
   • Using with C/C++
4. Development
   • Testing
   • Building IntelliSense
   • Building for Your Project
5. Resources

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Why Choose CompOS?

CompOS recognizes existing RTOS structures and mimics them at a lower-cost, more performant abstraction through utilizing the power of new compiler features that Zig and C++ offer. (Benchmarks are not done yet but it would be 1.5x performance while being slightly better memory efficiency). This library can be used with any C ABI-compatible languages.

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About Zig and C++

Traditional FreeRTOS Tasks Challenges:

1. Require separate stacks for each task, consuming significant memory.
2. Use manual creation and management via xTaskCreate, leading to verbose code.
3. Depend on synchronization mechanisms like semaphores or notifications, adding complexity.
4. Suffer memory overhead due to pre-allocated stacks, regardless of actual usage.
5. Introduce context switching latency, which impacts real-time responsiveness.

Zig’s async/await Solution:

1. State Machines Replace Stacks:
   • Zig coroutines store only the minimal state (variables and execution point), eliminating the need for per-task stacks.
2. Explicit Control with await:
   • Coroutines yield control explicitly at await, making them cooperative and reducing unnecessary context switches.
3. Reduced Memory Usage:
   • Tasks no longer require stacks, dramatically decreasing memory consumption.
4. Simplified Task Model:
   • Fewer APIs and boilerplate code compared to traditional task creation and management.

C++ Consteval and Constexpr Benefits:

5. Compile-Time Optimization with comptime:
   • Know the exact number of coroutines at compile time, enabling aggressive memory and performance optimizations.
6. Eliminate Heap Usage:
   • With all tasks and resources defined at compile time, the system can operate entirely without a heap.

Zig Benefit:

7. Unit Testing:

   • No need for google tests, instead use Zig's built in testing framework.

   Just Run:

   zig build -Dtest=true test --summary all

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How to Use CompOS

Using with Zig

Add the following dependency to your build.zig.zon to integrate CompOS into your project:

📄 build.zig.zon:

.dependencies = .{
    .CompOS = .{
        .url = "https://github.com/OmarSiwy/CompOS/archive/refs/tags/v0.0.6.tar.gz",
        .hash = "12206cc38df5a25da72f1214c8e1bc019f3dbd5c0fd358b229de40dcb5f97abc770c",
    },
},

📄 build.zig:

const ARTOS = b.dependency("CompOS", .{
    .Compile_Target = "<MCU_NAME>",
    .Optimization = "ReleaseSafe or Debug or ReleaseSmall or ...",
    .Library_Type = "Static or Shared",
});

// Your project setup:
const exe = b.addExecutable(.{
    .name = "project",
    .target = target,
    .optimize = optimize,
    .root_source_file = .{ .cwd_relative = "src/main.zig" },
    .linkerscript = output_path,
});
exe.linkLibrary(ARTOS.artifact("CompOS"));

Using with C/C++

To build and use CompOS with C/C++:

zig build -Doptimize=ReleaseSafe -DCompile_Target=testing -DLibrary_Type=Static

# Use the generated library and source files with your makefile (see examples for details).

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Development

Testing

Run tests with the following command:

zig build -Doptimize=ReleaseSafe -DCompile_Target=testing -DLibrary_Type=Static cdb # Generate Compile Commands file
zig build -Doptimize=ReleaseSafe -DCompile_Target=testing -DLibrary_Type=Static size # Find Library Size

Building for Your Project from Source

To build CompOS for your project:

zig build -Doptimize=ReleaseSafe -DCompile_Target=testing -DLibrary_Type=Static cdb # Nested Compile Commands for your project <3

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Resources

• Operating System: Three Easy Pieces

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