Speed of finding a size of an array.

[pemo]

<snip>

c) What is the difference between comp.lang.c and alt.comp.lang.c ?

Neither of the two news group servers I use list this.

 

[Malcolm]

(More seriously, C's model of the computing universe is
single-threaded and synchronous. If I were looking for things
to parallelize in C, I'd not worry about memset() until after
I'd done something about I/O.)

If you were a games programmer you'd have something called a DMA engine,
which will do block transfers and clears in parallel.
DMAmemcpy() is one of the first things to implement / learn how to use.

You do of course also have to learn how to use a pipelined graphics system,
and parallel audio. We cannot blank the screen every time a baddie dies with
a catchy tune.

 

[Eric Sosman]

If you were a games programmer you'd have something called a DMA engine,
which will do block transfers and clears in parallel.
DMAmemcpy() is one of the first things to implement / learn how to use.

Don't teach your grandmother to suck eggs. I was
writing parallel code before C was invented, running
simultaneous programs in the CPU and in the hardware of
two independent I/O channels, and getting the whole thing
to synchronize. Real-time streaming quadrophonic audio
from disk to A-to-D converter, using 1960's hardware.
(Full disclosure: The original version of this program
was written by someone else, but I wound up owning it for
a couple of years and extended it in various ways. I
learned a lot by reading that other guy's code; he was a
really good craftsman.)

Oddly enough, some of the now-unfashionable languages
and libraries of the time were able to overlap I/O with
processing, a capability lacking in C's simple model.
Nowadays we try to parallelize by foisting the problem
off on the O/S; this is effective to some extent, but
involves some compromises in throughput. I recently
trouble-shot a customer problem that arose entirely from
relying on the O/S to do the program's buffering for it;
if the program's I/O model had allowed it to control its
own buffering the problem would never have arisen.