On Tue, 24 May 2022 17:55:13 GMT, Paul Sandoz <psan...@openjdk.org> wrote:
>> Here's a concrete example: >> >> Consider a sequence layout with 6 elements. Then: >> >> element count = 6 >> valid indices 0, 1, 2, 3, 4, 5 >> >> Now consider a var handle that is obtained by calling the path element >> method, passing the following parameters >> >> start = 1 >> step = 2 >> >> This sets up the following mapping between logical an physical indices: >> >> 0 -> 1 >> 1 -> 3 >> 2 -> 5 >> >> Where on the LHS we have the logical index (the one passed to the VH) and on >> the RHS we have the actual index it is translated to. >> >> Note that the index map has three elements. So the upper bound (exclusive) >> of the index map is 3 - that is, we can pass indices 0, 1, 2. >> >> According to the formula shown in the javadoc: >> >> B = ceilDiv((elementCount - start) / step); >> >> so: >> >> B = ceilDiv((6 - 1) / 2) >> = ceilDiv(5 / 2) >> >> Note how, w/o ceilDiv we'd get 2 (the last valid index), and not 3 (the >> first invalid index). > > The terms `x_1, x_2, ... x__n` are defined, but `x_0` is not. > > I think you can refer to the first index out of bounds as the exclusive upper > bound of the range? Sorry i misread the text, we are talking about the same thing. I think it would be clearer to refer `x_i` being in the range of `0` (inclusive) and `b_i` (exclusive), otherwise an .... is thrown. That way in subsequent doc on other methods in matches with `B`, which is exclusive. ------------- PR: https://git.openjdk.java.net/jdk/pull/8868
