[bug #68091] Inefficient Integer Data Loading from MAT-Files

foreverallama <[email protected]> Thu, 16 Apr 2026 14:01:31 -0400 (EDT)

Newsgroups	gmane.comp.gnu.octave.bugs
Message-ID	<[email protected]>

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Follow-up Comment #11, bug #68091 (group octave):

Sorry, been a while. Got back into it today, and putting a patch up that
incorporates the changes we were looking into then.

I used "type_traits" with "if constexpr" for compile-time dispatch instead of
the macro. If the destination type and storage type match, that path should be
handled at compile time. We don't need to handle byte swap separately for
int8/uint8, it's already handled in "swap_bytes ()". Tests passed successfully
with "test/io.tst".

I don't believe we can remove the switch-case entirely, as we still need to
dispatch based on storage type which is known only at runtime. Hence, the main
change would be in removing the macro.

Some timing measures of performance below:

% Before Patch
octave:1> tic; load("large_int_arr.mat"); toc
Elapsed time is 0.296586 seconds.
octave:2> tic; load("large_object.mat"); toc
Elapsed time is 5.08949 seconds.

% After Patch
octave:1> tic; load("large_int_arr.mat"); toc
Elapsed time is 0.102456 seconds.
octave:2> tic; load("large_object.mat"); toc
Elapsed time is 2.84395 seconds.

% "large_int_arr" is a 3000x3000 uint8 array.
% "large_object" is an object instance of "ExampleClass" with a single
property "a" = 3000x3000 double.

Let me know what you think.

(file #58477)

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