Re: Manipulating C code at the AST level, in C

On 8/15/26 03:20, rbowman wrote:
> On Fri, 14 Aug 2026 23:47:19 -0400, c186282 wrote:
> 
>>     Polling, for this sort of thing, has to be
>>     fast and constant - a big CPU drag. You are
>>     basically WAITING for something to happen -
>>     which MAY or may NOT happen at any moment.
> 
> I used select() rather than poll() but I'm archaic. Typically the select
> call was in the main loop. The timeout was often 1 second. If the call
> returned a ready fd you took care of business. If it timed out, then you
> did whatever housekeeping was necessary, making sure it wasn't a long
> process.
> 
> Without the select the main loop would chew up 100% of the CPU. Interrupt
> have their place but often complex ISRs are used that aren't any faster
> than polling.

   Any kind of ISR is almost always the best
   solution to the described sort of need.
   Polling is CRUDE and, as we both said, eats
   CPU like mad.

   Having done stuff with a lot of micro-controllers,
   which don't have much CPU to spare anyway, always
   did ISRs whenever possible to get data from devices.
   Depending, the ISR can push events onto a sort of
   list/stack and then you can deal with them kinda
   all at once every x-often.

   Alas, the younger set ASSUMES kinda infinite
   CPU/mem. It's poor thinking, poor discipline.
   IMHO, "Intro To Programming" should always
   start with like PICs or basic Ards. Let 'em
   learn to get the most done with the least
   resource consumption. Sometimes requires being
   CLEVER and/or learning weird quirks of the
   hardware. But we NEED clever programmers !!!

   Tax calculations, almost any idiot can code an
   app. Next mission to Mars or Titan, we need
   REALLY damned clever humans. "AI" can be kinda
   good, but it's not really "clever" and does
   not seem to anticipate weird fails.

   Still wish we'd find satellite/space-probe
   software gurus in these groups. The hyper-
   durable/redundant systems they do are nearly
   black magic. How DO you cope when cosmic rays
   may flip bits anywhere anytime ? When some
   important chip FAILS entirely ? The hardware
   folks are fantastic as well ... remote
   reload/redo/reboot of the whole system on some
   3rd-tier backup mem chip ...