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DelSkayn / rquickjs

High level bindings to the quickjs javascript engine
MIT License
431 stars 58 forks source link

Support no_std targets #303

Open doinkythederp opened 2 months ago

doinkythederp commented 2 months ago

It'd be great if I could use the rquickjs crate on no_std targets as an embedded JavaScript engine.

DelSkayn commented 2 months ago

I am not an expert on no_std but I believe that such a target would not have a libc, which means we couldn't support it. QuickJS itself depends (quite heavily) on a libc being present.

richarddd commented 2 months ago

I actually think libc is not needed for the engine, but no_std would require our rust code with non standard lib (would require significant refactor) and custom allocator etc

DelSkayn commented 2 months ago

QuickJS uses libc for float parsing and a bunch of printf like formatting functions internally.

It is one of the reasons why compiling to rust it's default wasm target wasm32-uknown is not supported, since there is no libc in that platform.

richarddd commented 2 months ago

QuickJS uses libc for float parsing and a bunch of printf like formatting functions internally.

It is one of the reasons why compiling to rust it's default wasm target wasm32-uknown is not supported, since there is no libc in that platform.

You're right. Forgot about that!

doinkythederp commented 2 months ago

I am not an expert on no_std but I believe that such a target would not have a libc, which means we couldn't support it. QuickJS itself depends (quite heavily) on a libc being present.

Actually, many no_std targets have a libc! Oftentimes, the sysroot for the target (which includes libc and libm) can be installed and accessed through the platform's GCC toolchain. For example, when compiling for armv7a-none-eabi (Cortex A9), I can use headers from $(arm-none-eabi-gcc -print-sysroot)/include and link with $(arm-none-eabi-gcc -print-sysroot)/lib to get access to libc. (Although, depending on how you installed the toolchain, you may need to use a different command)

doinkythederp commented 2 months ago

You might find this useful - here is my port of rquickjs to armv7a-none-eabi: https://github.com/doinkythederp/rquickjs/tree/vexos-port (it could probably be used on other no_std targets too but I haven't tested them).

It probably won't be able to be directly merged because I had to make big changes to anything that needed something std-specific, like resolvers and loaders that access the file system.