windows-95

Your mission

Return how many ticks passed between two readings of a counter that rolls over.

today's brief

Redmond, 1999. Microsoft confirms that Windows 95 freezes after 49 days and 17 hours of uptime, because it counts milliseconds into a 32-bit value that runs out at exactly that point. Almost nobody noticed. The machines rarely stayed up long enough, and the ones that did usually fell over first for other reasons. A counter like that does not stop at the top. It rolls back to zero and carries on. Work out the gap between two readings of one.

See it in action

elapsed(100, 400, 1000)

Expected result

Your checklist

For your own tracking. Tests grade your code.

The counter takes the values 0 up to wrap - 1, then starts again at 0.
start and now are two readings of it, with now taken no more than one full turn after start.
Return how many ticks passed between the two readings.

More examples

elapsed(900, 100, 1000)

Expected result

Constraints

Expected files

ticks.c

Allowed functions

None. Write every helper yourself.

Back to compete

Solutions

windows-95

Your mission

Return how many ticks passed between two readings of a counter that rolls over.

today's brief

See it in action

elapsed(100, 400, 1000)

Expected result

Your checklist

For your own tracking. Tests grade your code.

The counter takes the values 0 up to wrap - 1, then starts again at 0.
start and now are two readings of it, with now taken no more than one full turn after start.
Return how many ticks passed between the two readings.

More examples

elapsed(900, 100, 1000)

Expected result

Constraints

Expected files

ticks.c

Allowed functions

None. Write every helper yourself.

Back to compete

Solutions