Re: counting_semaphore question

On Fri, 13 Sep 2024 12:54:53 +0200
David Brown <david.brown@hesbynett.no> boringly babbled:

On 13/09/2024 09:26, Muttley@dastardlyhq.com wrote:

Clearly you've never done any low level networking where id fields are fixed
sized and will eventually wrap. Eg, TCP sequence number. I'm sure there are
a myriad of other examples.

>
Clearly you can make up a complete load of drivel with no basis in reality.

Oh dear, someones been caught out and is throwing his toys out the pram.

So let me be /clear/ here.  There is /no/ valid use of incrementing
something beyond its maximum value.  The whole concept makes no sense.

Bollocks.

There /are/ lots of valid uses of wrapping types.  Sequence numbers in
low-level networking would be one example of that - one which I /have/
used countless times in my work.  But that is not incrementing beyond a
max value - it is using a modulo wrapping increment to give a result
/within/ the valid range, not beyond it.

Oh right, so for 32 bit TCP seq number instead of just doing:

++tcp->seq_num;

which would autonatically wrap after 2^32, in your world we'd have do to:

tcp->seq_num = (uint32_t)(((uint_64_t)tcp->seq_num + 1) % 0x100000000L);

Really?

Don't be an ass.

If you think thats clear I'd hate to see what you consider obtuse.
 

>
Have you ever considered that /you/ might be the problem here?  Other
people seem to understand it fine.  Consider the common factor in all
your difficulties understanding the template parameter.

If it wasn't so vague I wouldn't have needed to ask the question.

But does all this mean that you now understand what the integer template
parameter is for, and what it does?  And do you understand how to use
the counting semaphore?  If so, that's great.

Aww bless, so kind.