On 10/24/2013 11:33 AM, eles wrote:
On Thursday, 24 October 2013 at 17:02:51 UTC, Walter Bright wrote:
On 10/24/2013 4:18 AM, eles wrote:
On Thursday, 24 October 2013 at 06:48:07 UTC, Walter Bright wrote:
On 10/23/2013 11:19 PM, Mike wrote:
Like I said, nobody (on the standards committees) could agree on exactly what
that meant.
The standard committees might not agree, but there is somebody out there that
really knows very accurately what that should mean: that somebody is the
hardware itself.
Just imagine the best hardware example that you have at hand: the microprocessor
that you are programming for.
It writes on the bus, there is a short delay before the signals are guaranteed
to reach the correct levels, then reads the memory data and so on.
You cannot read the data before the delay passes. You cannot say "well, I could
postpone the writing on the address on the bus, let's read the memory location
first" -- or you would read garbage. Or you cannot say: well, first I will
execute the program without a processor then, when the user is already pissed
off, I would finally execute all those instructions at once. Too bad that the
computer is already flying through the window at that time.
You command that processor from the compiler. Now, the thing that's needed is to
give a way to do the same (ie commanding a hardware) from the program compiled
by the compiler.
The trouble with that is since the standards people cannot agree on what
volatile means, you're working with a compiler that has non-standard behavior.
This is not portable and not reliable.
