On Tue, 9 Jul 2024 17:17:48 GMT, Raffaello Giulietti <rgiulie...@openjdk.org> wrote:
> Let's agree that the reference for this PR is the > [algorithm](https://inria.hal.science/inria-00072113/document) described by > Bertot, Magaud and Zimmermann. > > From a first reading, the algorithm implemented here appears different in > many aspects from the one in the paper, making a direct comparison between > the twos rather hard. For example, the paper normalizes the input to an even > number of words ("limbs"). AFAIU, this doesn't seem to happen here. There > might be good reasons to depart from what is described in the paper, but > there's no discussion. > > To ease the reviewing process, and for the benefit of future maintainers, > every departure from the paper should be discussed and mathematically > justified to some extent in comments. @rgiulietti The input is normalized in the method called `sqrtRemZimmermann`, and is normalized to a number of words which is a multiple of 4, and of course a multiple of 4 is even. For speed, the normalization is performed only "logically", which means that the contents of the input are not changed, but only its logical length, which is stored in the variable `len`. The reason why the length is normalized to a mutiple of 4 is that, in this way, the input can be always split in blocks of words without twiddling with bits. I am completely available for further clarifications regarding the algorithm code. ------------- PR Comment: https://git.openjdk.org/jdk/pull/19710#issuecomment-2218328258
