66 lines
2.2 KiB
Markdown
66 lines
2.2 KiB
Markdown
# wasm-c-api introduction
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wasm-c-api is an engine-agnostic API to embed a WASM engine.
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In wasm-micro-runtime, it's provided by the header file `wasm_c_api.h`.
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Its functionalities are overlapping with `wasm_export.h`, which is
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a native API of wasm-micro-runtime. An embedder is supposed to pick
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one of these APIs, rather than mixing both of them.
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All samples come from the commit 340fd9528cc3b26d22fe30ee1628c8c3f2b8c53b
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of [wasm-c-api](https://github.com/WebAssembly/wasm-c-api).
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Developer can learn these _APIs_ from
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[wasm.h](https://github.com/WebAssembly/wasm-c-api/blob/master/include/wasm.h).
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And here are [examples](https://github.com/WebAssembly/wasm-c-api/tree/master/example) which
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are helpful.
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## FYI
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- The thread model of _wasm_c_api_ is
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- An `wasm_engine_t` instance may only be created once per process
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- Every `wasm_store_t` and its objects may only be accessed in a single thread
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- `wasm_engine_new`, `wasm_engine_new_with_config`, `wasm_engine_new_with_args`,
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`wasm_engine_delete`should be called in a thread-safe environment. Such
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behaviors are not recommended, and please make sure an appropriate calling
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sequence if it has to be.
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- call `wasm_engine_new` and `wasm_engine_delete` in different threads
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- call `wasm_engine_new` or `wasm_engine_delete` multiple times in
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different threads
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## unspported list
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Currently WAMR supports most of the APIs, the unsupported APIs are listed as below:
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- References
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```c
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WASM_API_EXTERN own wasm_shared_##name##_t* wasm_##name##_share(const wasm_##name##_t*);
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WASM_API_EXTERN own wasm_##name##_t* wasm_##name##_obtain(wasm_store_t*, const wasm_shared_##name##_t*);
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```
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- Several Module APIs
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```c
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WASM_API_EXTERN void wasm_module_serialize(const wasm_module_t*, own wasm_byte_vec_t* out);
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WASM_API_EXTERN own wasm_module_t* wasm_module_deserialize(wasm_store_t*, const wasm_byte_vec_t*);
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```
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Currently growing a table or memory by wasm opcode is supported and it is not supported to grow them
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by host-side function callings.
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- Table Grow APIs
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```c
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WASM_API_EXTERN bool wasm_table_grow(wasm_table_t*, wasm_table_size_t delta, wasm_ref_t* init);
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```
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- Memory Grow APIs
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```c
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WASM_API_EXTERN bool wasm_memory_grow(wasm_memory_t*, wasm_memory_pages_t delta);
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```
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