This may be useful for compression in the future, where compression +
noise can result in blocks _larger_ than the expected weight.
Thinking about how compression might be integrated into littlefs, it
would be nice if such a topology did _not_ trigger asserts. This would
allow littlefs images to interact with compressed files at least a
little bit (rename/remove could be very useful), even if the compression
algorithm isn't supported.
Supporting this requires only a single clamp in lfsr_file_lookupleaf,
but it's a little bit more costly than you might expect:
code stack ctx
before: 35692 2440 640
after: 35740 (+0.1%) 2440 (+0.0%) 640 (+0.0%)
This is due to internal API awkwardness:
1. LFSR_DATA_TRUNCATE is surprisingly costly
2. We need to create a local weight copy in case the caller's is NULL
Christopher Haster
0a485da7c9