stk (Stalwart Toolkit)

stk is a lightweight, modular toolkit for building games and game engines. It provides a portable foundation for dynamically loading modules, native or WASM, without enforcing any architecture or design choices.

It is designed to run on modern systems running POSIX and Windows using C89.

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Key Features

• Dynamic module loading (native .so / .dll / .dylib)
• Hot-swapping of modules at runtime
• Cross-platform (Linux, BSD, Windows, macOS)
• Optional WASM support for multi-language modules (planned)
• Developer tools: lightweight metadata, logging/tracing, and dependency management
• Minimal, portable API

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Philosophy

stk is non-opinionated: developers control architecture, engine design, and game logic while relying on a predictable, lean foundation.

See docs/design.md for the full design philosophy and roadmap.

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Quick Start

Building

# Unix (Linux/BSD/macOS)
./build.sh debug release

# Windows
build.bat debug release

Installation

Unix (Linux/BSD/macOS)

./build.sh install

Installs to /usr on Linux, /usr/local on BSD/macOS by default. Use PREFIX to customize:

./build.sh PREFIX=$HOME/.local install

Windows

build.bat release

• Once finished building, copy the headers from include/ to your_project/include/stk/ and copy bin/release/stk.dll or bin/release/stk.lib to your project's lib directory, depending on whether you are linking dynamically or statically.

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Usage

Basic Example

#include <stk/stk.h>
#include <stdio.h>

int main(void)
{
    int running = 1;
    size_t events;
    
    /* Initialize stk */
    if (stk_init() != STK_INIT_SUCCESS) {
        fprintf(stderr, "Failed to initialize stk\n");
        return 1;
    }

    /* Main loop - poll for module changes */
    while (running) {
        events = stk_poll();
        if (events > 0) {
            printf("Detected %zu module event(s)\n", events);
        }
        
        /* Your game/application logic here */
    }

    /* Shutdown stk systems*/
    stk_shutdown();
    return 0;
}

Creating a Module

Modules are simple shared libraries with stk_mod_init and stk_mod_shutdown functions:

/* my_module.c */
#include <stdio.h>

int stk_mod_init(void)
{
    printf("Module loaded!\n");
    return 0;  /* Return 0 on success */
}

void stk_mod_shutdown(void)
{
    printf("Module unloaded!\n");
}

Build as a shared library:

# Linux/BSD
cc -shared -fPIC -o my_module.so my_module.c

# macOS
cc -shared -fPIC -o my_module.dylib my_module.c

# Windows (MSVC)
cl /LD my_module.c /Fe:my_module.dll

# Windows (MinGW)
cc -shared -o my_module.dll my_module.c

Place the compiled module in the mods/ directory (default), and stk will automatically load it and watch for changes.

Module Metadata

Modules can optionally export metadata functions:

const char *stk_mod_name(void)        { return "My Module"; }
const char *stk_mod_version(void)     { return "1.2.0"; }
const char *stk_mod_description(void) { return "Does something useful"; }

All three are optional. Version defaults to 0.0.0 if not exported or unparseable.

Declaring Dependencies

Modules declare dependencies via an exported sentinel-terminated array. No stk headers are required in the module. The only requirement is that the memory layout matches: { char[64], char[32] }.

typedef struct {
    char id[64];
    char version[32];
} dep_t;

dep_t stk_mod_deps[] = {
    { "physics", ">=2.0.0" },
    { "renderer", "^1.0.0" },
    { "", "" }  /* sentinel */
};

Version constraint operators:

• =1.0.0 exact match
• >=2.0.0 minimum version, also the default if no operator is specified
• ^1.0.0 same major, greater or equal minor/patch

If a dependency is removed at runtime, all affected modules are unloaded and queued. When the dependency comes back, they load automatically.

Configuration

/* Set custom module directory (default: "mods") */
stk_set_mod_dir("custom_mods");

/* Set custom temp directory name (default: ".tmp") */
stk_set_tmp_dir_name(".my_tmp");

/* Set custom init function name (default: "stk_mod_init") */
stk_set_module_init_fn("my_init");

/* Set custom shutdown function name (default: "stk_mod_shutdown") */
stk_set_module_shutdown_fn("my_shutdown");

/* Set function name to get module name (default: "stk_mod_name") */
stk_set_module_name_fn("my_mod_name");

/* Set function name to get module version (default: "stk_mod_version") */
stk_set_module_version_fn("my_mod_version");

/* Set function name to get module description (default: "stk_mod_description") */
stk_set_module_description_fn("my_mod_description");

/* Set deps array symbol name (default: "stk_mod_deps") */
stk_set_module_deps_sym("my_mod_deps");

/*
 * All the above functions must be called before stk_init()
 * if the defaults need to be changed.
 */
stk_init();

API Reference

Initialization

• unsigned char stk_init(void) - Initialize stk, returns STK_INIT_SUCCESS on success
• void stk_shutdown(void) - Shutdown and cleanup all modules

Runtime

• size_t stk_poll(void) - Poll for module changes, returns number of events processed
• size_t stk_module_count(void) - Get number of currently loaded modules

Configuration

• void stk_set_mod_dir(const char *path) - Set module directory
• void stk_set_tmp_dir_name(const char *name) - Set temp directory name
• void stk_set_module_init_fn(const char *name) - Set module init function name
• void stk_set_module_shutdown_fn(const char *name) - Set module shutdown function name
• void stk_set_module_name_fn(const char *name); - Set module name function name
• void stk_set_module_version_fn(const char *name); - Set module version function name
• void stk_set_module_description_fn(const char *name); - Set module description function name
• void stk_set_module_deps_sym(const char *name) - Set module deps array symbol name (default: stk_mod_deps)

Logging

• void stk_set_logging_enabled(unsigned char enabled) - Enable/disable all logging
• unsigned char stk_is_logging_enabled(void) - Query logging state
• void stk_set_log_output(FILE *fp) - Set log output stream (default: stdout, NULL disables)
• void stk_set_log_prefix(const char *prefix) - Set log prefix (default: "stk")
• void stk_set_log_level(stk_log_level_t level) - Set minimum log level (default: INFO)

Log Levels: STK_LOG_ERROR, STK_LOG_WARN, STK_LOG_INFO, STK_LOG_DEBUG

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Project Status

Current Version: 1.0.0-pre.11

What Works

• Cross-platform module loading and hot-reloading
• File watching (inotify/kqueue/FindFirstFile)
• Robust hot-reload even during extremely rapid file changes
• Enhanced logging with levels, timestamps, and filtering
• Runtime-configurable logging behavior
• Optional module metadata (name, version, description)
• Dependency declaration, validation, and versioning
• Detailed dependency failure logging (missing ids, version mismatches)
• Cascade unload when dependencies are removed
• Pending queue with automatic retry when deps become available
• Topological sort with cycle detection

Phase 2

• WASM module support

See CHANGELOG.md for detailed release notes.

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Testing

Run the included test suite:

./build.sh test    # Unix
build.bat test     # Windows

The test will watch the mods/ directory and report when modules are loaded, reloaded, or unloaded.

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License

Mozilla Public License 2.0 (MPL-2.0)

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Contributing

Contributions welcome! Please ensure code follows C89 standard and works across all supported platforms.