On Mon, May 20, 2024 at 7:41 PM Kannan Varadhan <kvaradhan3@gmail.com> wrote:

Hi folks:

This was an interesting pointer.  I am puzzled about some of the
zsh-isms here and the logic, so

some questions:

     while (( $#bytes < 4 )); do
       sysread -s$((4-$#bytes)) 'bytes[$#bytes+1]' </dev/urandom || return
     done

It looks like we want 4 individual byes (the sysread promises anywhere
from 1 to size of buffer specified, max 8192 (in zshmodules(1)) but may
return after only reading 1B.    So why not only say `-s1` instead of
the more involved `-s$((4-$#bytes))`?

Reading 1 byte at a time is slower than reading 4 bytes at once.

ok but the loop seems to read 4, then 3, 2, and 1B in each iteration, or did I miss something?

     local b1=$bytes[1] b2=$bytes[2] b3=$bytes[3] b4=$bytes[4]
     return '#b1 << 24 | #b2 << 16 | #b3 << 8 | #b4'

Why copy to a scalar parameters

My goal was to implement the contract described in the comments. This
is how I managed to do it. Your asking "why" appears to imply that you
have another implementation in mind that is more natural to you. If
so, can you post it?

i dont have an alternate implementation.  I was trying to use '#bytes[1]' directly and that did not work.

what does referring to them as '#b1', #b2', ... mean.

These are the numeric values of the bytes held in b1..b4.

    % x='A'
    % print -r -- $(( #x ))
    65

Interesting, 

Kannan