Writing make-sized-byte-string alternative on CS

[Sage Gerard]

The docs for make-sized-byte-string indicate that CS does not support this operation. I'm guessing I just need to fall back to building a loop using ptr-ref, but is there something about CS that would prevent me from doing that too?

~slg

[Matthew Flatt]

You use `make-bytes` and `memcpy`, instead of writing a new loop. (The
non-copying part of `make-sized-byte-string` is what CS can't support.)

Matthew

At Tue, 15 Sep 2020 21:12:22 +0000, Sage Gerard wrote:
> The docs for
> [make-sized-byte-string](https://docs.racket-lang.org/foreign/foreign_pointer-f
> uncs.html?q=free#%28def._%28%28quote._~23~25foreign%29._make-sized-byte-string%
> 29%29) indicate that CS does not support this operation. I'm guessing I just

> need to fall back to building a loop using ptr-ref, but is there something
> about CS that would prevent me from doing that too?
>
> ~slg
>

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[Sage Gerard]

Thank you for the rapid response!


~slg

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐

On Tuesday, September 15, 2020 5:15 PM, Matthew Flatt <mfl...@cs.utah.edu> wrote:

> You use `make-bytes` and `memcpy`, instead of writing a new loop. (The
> non-copying part of `make-sized-byte-string` is what CS can't support.)
>
> Matthew
>
> At Tue, 15 Sep 2020 21:12:22 +0000, Sage Gerard wrote:
>
> > The docs for
> > [make-sized-byte-string](https://docs.racket-lang.org/foreign/foreign_pointer-f

> > uncs.html?q=free#%28def.%28%28quote.~23~25foreign%29._make-sized-byte-string%

> > 29%29) indicate that CS does not support this operation. I'm guessing I just
> > need to fall back to building a loop using ptr-ref, but is there something
> > about CS that would prevent me from doing that too?
> > ~slg
> > --
> > You received this message because you are subscribed to the Google Groups
> > "Racket Users" group.
> > To unsubscribe from this group and stop receiving emails from it, send an
> > email to racket-users...@googlegroups.com.
> > To view this discussion on the web visit
> > https://groups.google.com/d/msgid/racket-users/P-nFrHLWq2Hs3MxhcsA09NoQtGaw0LfG
> > 5WE-nC_IHWGSl3rPhToCquz8spEVDUAqg-LJRYweeGmerH12XTUUFhXBOHgBDAabpQk-2b2gFiQ%3D%
> > 40sagegerard.com.
>
> --
>
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