How do you iterate backward over circular buffer without a conditional?
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26-09-2019 - |
Question
Iterating forward through a circular buffer without using a conditional is easy with the remainder operator...
iterator = (iterator + 1) % buffer_size;
I can't for the life of me figure out the reverse operation, iterating backward.
Solution
Does iterator = (iterator + buffer_size - 1) % buffer_size
work for you? Go one less than all the way around.
OTHER TIPS
Borealid's answer works. (note: iterator
is set to 0 initially).
Another solution is
iterator = buffer_size - 1 - (buffer_size - iterator) % buffer_size
with iterator
set to buffer_size
initially.
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