Re: I wonder if I'm missing something...

> On 8 Nov 2025, at 23:21, David McClain (as dbm at refined-audiometrics dot com) <[email protected]> wrote:
> 
> So now, I can read :UINT8 bytes from a Socket stream, directly into a stack allocated octet buffer, then turn around and use the FLI:REPLACE-FOREIGN-ARRAY to convert that buffer of octets into a buffer of single-float values in just one copy operation:
> 
> 	(let ((buf   (make-array  16
>                                   :element-type ‘(unsigned-byte 8))))
> 	   (declare (dynamic-extent buf))
> 	   (READ-SEQUENCE buf socket-stream)
> 	   (FLI:REPLACE-FOREIGN-ARRAY my-float-vec (fli:make-pointer :type :FLOAT
>                                                                      :address (+ 8 (SYS:OBJECT-ADDRESS buf)))
>                                       :end2 4))

I am not quite sure you are achieving what you think you are achieving here, it seems like you are making even more copying than there was at the start. As I understand it, the data from sockets gets to LW by these steps:

1. Data is written to the kernel’s network buffer. We are not involved here in any way.
2. A kernel call to recv() from LW fills the underlying buffer of the socket-stream by copying from the network buffer. No way to avoid copying here (sort of, kinda possible in Linux).
3. You copy data from the stream into your own buffer making Lisp calls to read-byte and read-sequence.

There is only one “unneeded” copying at step 2 but it is needed if you want to work with a Lisp stream. Since read-sequence does not work in your case, so you just should use read-byte and go on about your day. If you really do not want to use read-byte here, then you just patch into the step 2 with your own buffer and avoid using the Lisp byte stream altogether.