5 releases
0.1.4 | Apr 22, 2024 |
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0.1.3 | Apr 22, 2024 |
0.1.2 | Apr 22, 2024 |
0.1.1 | Apr 22, 2024 |
0.1.0 | Apr 22, 2024 |
#321 in Embedded development
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11KB
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Per-core static stat on RP2040
The RP2040 is a dual-core microcontroller. The rp2040-hal multicore
module
makes it easy to start code running on the second core, but doing so adds some
complications. Any static
variables are shared in memory, causing the same
difficulties that static variables do in multithreaded systems.
This package enables the use of the unstable #[thread_local]
attribute to mark
a static
variable as core-local. Each core gets its own instance of any such
variables and can use and manipulate them completely independently.
Because these variables are not shared, their contents need not be Send
or
Sync
, so you can, for example, use a RefCell
's interior mutability to manage
them.
Unlike thread-local variables, their states are initialized once on system reset, not when code is spawned onto a core. Therefore if you spawn multiple times onto core 1, then later spawns will see the state left behind by the previous runs.
Notes on Usage
The implementation needs the linker script to set up the layout of per-core
state in memory. You therefore need to copy the relevant portions of memory.x
into your own linker script.
It also needs this crate to define the __aeabi_read_tp
function to read the
per-"thread" state. You need to add
extern crate rp2040_multicore_per_cpu;
to make sure this crate is pulled in so that this symbols will be linked in.
Dependencies
~1.5MB
~36K SLoC