Brendan Simon. wrote
> I am a big PowerPC fan but I would like to know the reasoning behind the
> Linux/PPC people choosing unsigned char as the default char type. Why go
> against the convention ? I hope there is a really good reason that will help
> progress the C programming environment to better things.
I'm told for ARM it is a performance issue. I've handled dozens of
these on the ARM port. In almost all of them it is a getc/getchar
that is being coerced down to a char before being checked agains EOF.
getc and getchar are (int) functions, EOF is an int. You can't cast
down to a char until you know you have a character and not an EOF.
Code with downcasts before checking EOF will fail one way on PPC and ARM
and the opposite way anytime it encounters a (char)255 in its input
stream.
Fortunately some wise soul extended the ARM compiler to print a warning
when a `char' is compared to a negative constant. We collect these during
the builds and list them over at...
http://www.federated.com/~jim/arm/charhell.html
... there are only about 150 packages left with this problem.
There are still packages like gnome-pim that can't be detected by the
compiler, but anytime a program hangs or fails to read a file this is
the first thing to look for on the ARM port.
I'll write a little script to blow all the compiler detected problems
into the BTS. We'll see how many we can get cleaned up.
--
Jim Studt, President
The Federated Software Group, Inc.
