feat: add blas/ext/base/gmskrev

[headlessNode]

Resolves stdlib-js/metr-issue-tracker#195.

Description

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This pull request:

• add blas/ext/base/gmskrev

Related Issues

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This pull request has the following related issues:

• Resolves [RFC]: add blas/ext/base/gmskrev metr-issue-tracker#195

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No.

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• Read, understood, and followed the contributing guidelines.

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Coverage Report

Package	Statements	Branches	Functions	Lines
blas/ext/base/gmskrev	$\color{green}353/353$ $\color{green}+0.00%$	$\color{green}27/27$ $\color{green}+0.00%$	$\color{green}3/3$ $\color{green}+0.00%$	$\color{green}353/353$ $\color{green}+0.00%$

The above coverage report was generated for the changes in this PR.

[kgryte]

This is not correct. Why do pairs need to both be unmasked? This means that one value can effectively mask another. A mask is intended to reduce the domain of which values are reversed.

Consider the following trivial example:

var x = [ 1, 2, 3 ];
var mask = [ 1, 0, 0 ];

gmskrev( ..., x, ..., mask, ... )

By your logic, the result should be

[ 1, 2, 3 ]

But that is not the right result. It should be

[ 1, 3, 2 ]

This affects all of this and related PRs.

[kgryte]

Loop unrolling is not useful for this implementation. You should refactor to use a single loop.

[kgryte]

While this implementation is incorrect, this is the only loop which is necessary. Loop unrolling is not particularly effective when you have nested conditionals.

[kgryte]

See how https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/strided/mskmax#mskmax-n-x-stridex-mask-stridemask- is documented.

[kgryte]

This can be removed once you update above.

[kgryte]

Left initial comments. This and related PRs need quite a bit of clean-up and refactoring.