rtic/book/en/src/by-example/tips_indirection.md

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 memcpys. 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.

Here's an example where heapless::Pool is used to "box" buffers of 128 bytes.

{{#include ../../../../examples/pool.rs}}

$ cargo run --target thumbv7m-none-eabi --example pool
{{#include ../../../../ci/expected/pool.run}}