Convert to and from Int24

I am want to try an Int24 type, purely for storage. It is easy to declare one with

primitive type Int24 <: Signed 24 end

but I am not sure how to access its value.

I only need conversion to and from Int32, but I don’t think I can use reinterpret because they don’t have the same number of bits. How can I convert to and from Int32?

(BTW, I am aware that I destroy alignment and it will degrade performance; it is an experiment)

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Once you find out, it would be great to update the docs with an example like this (or a simpler one).


There is an example in test/intrinsics.jl:

primitive type Int24 24 end
Int24(x::Int) = Core.Intrinsics.trunc_int(Int24, x)
Int(x::Int24) = Core.Intrinsics.zext_int(Int, x)

which actually solves my problem, but it may not be general enough to add to the manual.


It would be interesting to see how well LLVM supports this these days. Once upon a time, “strange” bit sizes were very poorly supported but it may have gotten better.