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Lokathor / wide

A crate to help you go wide. By which I mean use SIMD stuff.
https://docs.rs/wide
zlib License
279 stars 23 forks source link

newbie questions #101

Closed ImUrX closed 3 years ago

ImUrX commented 3 years ago

im wanting to do an unsigned right shift with an i64x2/4, should i simply convert the vector to an u64 vector?

another stupid question, why is wrapping not supported? from what i understand rust in dev builds panics by default if a number overflows/underflows, shouldnt the same happen in here?

Lokathor commented 3 years ago

If you don't want to preserve the sign bit when you right shift you should convert to an unsigned integer type, do the right shift, and then convert back to a signed integer type. The cast function from the bytemuck crate is great for this, and the optimizer will sort it out very well.

As to wrapping, all the operations are wrapping in both dev and release builds. SIMD doesn't allow for easy overflow detection, which means that trying to panic on an overflow is not very realistic.

ImUrX commented 3 years ago

alright thanks for the suggestion on bytemuck, i will have to read the docs on it

sad about the wrapping side, its a feature i like in rust, even tho i use wrapping a lot, panics for knowing that something is overflowing when you dont want that to happen is a good feature (this only happens in dev builds)