If you're trying to arrange that an array size is large enough for
element n to exist, and you also want to round it up to the next
multiple of 0x100, you must set the size to (n + 0x100) & ~0xFF, and
not (n + 0xFF) & ~0xFF. Put another way, the number you have to round
up is not n, but the minimum size n+1 that causes array[n] to exist.
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