44 lines
2.4 KiB
Markdown
44 lines
2.4 KiB
Markdown
# Oh My Rust FFI
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Sarasas Chip Workshop Oh My Rust FFI (abbr. SarasaCW OMRF) is a toolset including following components:
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- A Rust crate providing various facilities for C-friendly FFI.
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- A Python written tool for creating distribution and generating CMake and pkg-config files.
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- A document instructs how to design C-friendly FFI signatures and write C/C++ header files,
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involving how to pass primitive type, enum type, string and Rust specific structs like `Option`, `Result`.
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## Why not XXX?
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This toolset is specifically served for the Rust workflow and usage in Sarasas Chip Workshop.
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Because we have browsed the most of popular Rust FFI solutions and no one fit our requirements.
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So we develop it for our special requirements.
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### Not `cbindgen`
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`cbindgen` is a good tool but it only simply resolve only one Rust source file.
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It can't handle `use` syntax and means that we need put all things into single file.
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For a large-scale FFI interface, this behavior is unacceptable.
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### Not `Diplomat`
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Mozilla developed `Diplomat` is another great tool but it still doesn't fit our requirements.
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`Diplomat` prefers integrating Rust in workflow rather than distributing Rust built artifacts.
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Although `Diplomat` generated C/C++ header files can correctly process module relation and `use` syntax,
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it generated header files involve too much hacks and memory layout assumption based on target triple.
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This behavior causes that it generated header files only works on build machine and can not be distributed.
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It violates our requirements that we want our developed Rust projects can be distributed like a normal CMake project.
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Sarasas Chip Workshop developed Rust projects has no requirement that exposing complex structs like
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`Option`, `Result`, `Vec`, Generic and etc.
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All of these complex concepts are transformed into C-friendly pattern when exposing them.
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So the feature of `Diplomat` about handling complex structs is not only not helping us, but is actually a burden to us.
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### Not `cargo-c`
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`cargo-c` is the tool that comes closest to what we need by configuring some essential metadatas.
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But it doesn't support CMake generation. It only supports pkg-config.
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Considering some of our developed projects involve MSVC-only Windows environment, this is unacceptable.
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In addition, a small annoy spot is that installing `cargo-c` takes too much dependencies.
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It is a little bit uncomfortable but still okey.
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