use const steal

[xoviat]

The steal function is already unsafe, so there's no need to mark taken to make sure that someone else doesn't take it.

[wt]

Doesn't the steal function need to mark the peripherals taken so that take will work as intended? Otherwise, using take after steal will get the peripherals when we don't know that there is exclusive access via take.

[xoviat]

Otherwise, using take after steal will get the peripherals when we don't know that there is exclusive access via take.

Yes, and this is the correct result. steal is already unsafe, therefore, if you call it, you cannot guarantee that other code somewhere else does not have a duplicate instance of the peripherals. It is therefore your job to make sure that this isn't a problem.

However, suppose you are writing unsafe code and you need to call cortex-m methods, while still allowing safe code to take them. There is no way to do so without using a transmute, because calling steal will impact take.