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Commit Graph

3 Commits

Author SHA1 Message Date
Saleem Rashid
b4eaf7dbaf timer: Fix non-critical integer overflow (#129)
Every 4294967295 milliseconds (2 ^ 32 - 1), system_millis will overflow.
This means that every 49.71 days, system_millis will reset to zero.
Comparisons like `system_millis < (system_millis + 1)` would fail if the
latter had overflown and the former had not.

This is non-critical because the worst case is that one second could be
skipped or the screen could lock early.

This poses no threat to the exponential backoff used for protection
against brute force.
2016-11-23 20:22:28 +01:00
Saleem Rashid
0ec32a6146 timer: Replace screen timeout with SysTick
This provides an incredibly accurate screen timeout and removes the
superfluous screen timeout counter
2016-11-17 02:07:46 +01:00
Saleem Rashid
25b9bfd97b timer: Use Cortex-M3 SysTick timers
Removed `usbDelay(uint32_t cycles)`, added `usbSleep(uint32_t millis)`

The same method signature could cause silent code breakage at runtime,
as opposed to noisy code breakage at compile time which is the better
kind.
2016-11-17 02:07:46 +01:00