C Bindings for nim-timer

Purpose

This folder contains auto-generated C bindings for the my_timer Nim library. It is generated from ../timer.nim and provides:

my_timer.h: header-only C binding (MyTimerCtx + my_timer_ctx_* API)
main.c: example executable demonstrating how to use the bindings
CMakeLists.txt: build configuration that compiles the Nim library, the vendored TinyCBOR, and the C example

The bindings speak CBOR on the wire (the same format as the Rust and C++ backends) using the TinyCBOR copy vendored at ffi/codegen/templates/cpp/vendor/tinycbor.

How It's Generated

Regenerate these bindings by running from the parent directory:

cd examples/timer
nimble genbindings_c

This invokes the Nim compiler with -d:targetLang=c, triggering genBindings(...) in timer.nim, which reads the compile-time FFI registries and emits the binding files.

Building the Example

cd examples/timer/c_bindings
cmake -S . -B build
cmake --build build
./build/my_timer_example

Asynchronous API

Every method and the constructor take a typed result callback and return immediately. The callback fires exactly once — synchronously if the request fails to even submit, otherwise from the Nim dispatch thread when the reply arrives:

static void on_echo(int err_code, const EchoResponse* reply,
                    const char* err_msg, void* user_data) {
    if (err_code != 0) { /* err_msg is set, reply is NULL */ return; }
    printf("echoed: %s\n", reply->echoed.data);
}
...
my_timer_ctx_echo(ctx, &req, on_echo, /*user_data=*/NULL);

See main.c for the full pattern, including a small wait_done() poll helper that turns each async call back into a sequential step.

Memory Ownership

Request-side strings/sequences are borrowed — wrap C strings with nimffi_str(...); the binding never frees them.
Reply values and error strings passed into a result callback are owned by the binding and valid only for the duration of that callback. The caller never frees them — copy out anything you need to keep before returning.
A MyTimerCtx* delivered to the constructor callback is the exception: ownership transfers to you, and you release it with my_timer_ctx_destroy().

Do Not Edit

The generated files in this folder are overwritten each time nimble genbindings_c runs. Any manual changes will be lost.

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