Check that `SYST.set_reload`'s argument is valid

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
76/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Quiet
Tech stack
rust
Domain
embedded-iot

Research direction

Start in cortex-m/src/peripheral/syst.rs around the documented SYST.set_reload caveat at line 178, then inspect the set_reload entry point and its argument handling. Done means values exceeding the valid 24-bit range are rejected instead of silently overflowing, with behavior consistent with the existing documentation.

Written by the indexing model from the issue text.

Description

enhancement

The SYST.set_reload takes a number of cycles as an argument. Even though the type of this argument is an u32, only values that fit on 24 bits are valid. The code does document this caveat, however in practice there is no check being enforced.

As a result, it's very easy to pass a value that's too large and that will silently overflow, leading to a hard-to-diagnose incorrect behavior.

Would it make sense to add an assertion about the argument there?

Dominant language
Rust
Stars
1k
Forks
202
Avg merge
6d 2h
Merged PRs (30d)
2

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