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Diffstat (limited to 'book/en/src/by-example/tips_indirection.md')
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diff --git a/book/en/src/by-example/tips_indirection.md b/book/en/src/by-example/tips_indirection.md new file mode 100644 index 0000000..22c5774 --- /dev/null +++ b/book/en/src/by-example/tips_indirection.md @@ -0,0 +1,26 @@ +# Using indirection for faster message passing + +Message passing always involves copying the payload from the sender into a +static variable and then from the static variable into the receiver. Thus +sending a large buffer, like a `[u8; 128]`, as a message involves two expensive +`memcpy`s. To minimize the message passing overhead one can use indirection: +instead of sending the buffer by value, one can send an owning pointer into the +buffer. + +One can use a global allocator to achieve indirection (`alloc::Box`, +`alloc::Rc`, etc.), which requires using the nightly channel as of Rust v1.37.0, +or one can use a statically allocated memory pool like [`heapless::Pool`]. + +[`heapless::Pool`]: https://docs.rs/heapless/0.5.0/heapless/pool/index.html + +Here's an example where `heapless::Pool` is used to "box" buffers of 128 bytes. + +``` rust +{{#include ../../../../examples/pool.rs}} +``` + +``` console +$ cargo run --target thumbv7m-none-eabi --example pool +{{#include ../../../../ci/expected/pool.run}} +``` + |
