On Thu, Dec 24, 1998 at 11:57:04AM +0100, Michel Van den Bergh wrote:

> Reading  the discussions about C compilers for PIC micro
> controllers it seems to that the obvious solution is that somebody
> targets gcc (GNU cc) for the PIC family of micro controllers.

While gcc is a very effective compiler for 32 bit RISC processors, it
does not have a structure that works well on highly irregular, resource-poor
microntrollers. There are ports of gcc for other 8 bit micros (e.g.
the 68HC11) but they don't compare well with commercial compilers.
The PIC is a *far* more difficult chip to compile for than the HC11 even,
and porting gcc to the PIC probably represents 3-4 man-years of work (to
achieve a good, reasonably complete result).

To begin with, there is the simple fact that the PIC has no usable
stack, and gcc has no support for a compiled stack. That alone would
probably represent 6 months work (it needs a new linker to start with).

Then there are issues like the fact that the PIC has no registers in
the sense that a Sparc or 68000 has registers - gcc has a structure that
is oriented toward evaluation of expressions in registers, and while you
can simulate that on the PIC with memory, the result is highly inefficient.

I know of one compiler-specialist company that embarked on writing a PIC
compiler and gave up - and I'm not talking about IAR, though their PIC
compiler is at least 12 months late already, and still to see the light
of day.

So while I've got nothing against the idea of a free PIC compiler, I suggest
you don't hold your breath.

So with that, let me wish a Merry Christmas to all, and to all a Good Night!

Cheers, Clyde

--
Clyde Smith-Stubbs               |            HI-TECH Software
Email: clyde@htsoft.com          |          Phone            Fax
WWW:   http://www.htsoft.com/    | USA: (408) 490 2885  (408) 490 2885
PGP:   finger clyde@htsoft.com   | AUS: +61 7 3355 8333 +61 7 3355 8334
---------------------------------------------------------------------------
HI-TECH C: compiling the real world.