There has been some discussion on the use of C compilers with re-entrant
routines.  Then mention of heavy stack usage and the word recursive came
up.  Recursive routines (ones that call themselves) obviously must be
re-entrant, but re-entrant routines do not need to be used recursively.
The real heavy stack usage comes with recursive routines.  The one
application that comes to mind for using a recursive routine is printing
out a tree or other data structure.

While I do agree that a recursive routine does tend to gobble up the stack
and is somewhat indeterminant as to how much RAM will be used, the
re-entrant routine may not be as hoggish.  The compiler I use for the
68HC11 (Whitesmiths) has recursive routines and they are a must for me.  If
I am in the middle of a math computation (e.g. divide), and an interrupt
occurs where the ISR needs to perform the same kind of math computation,
the math routine better be re-entrant.  But just because those two routines
are using the math function at the same time does not mean a large amount
of stack space is used.  So re-entrant routines are a must in embedded
applications where interrupts call routines.

Which comes to the bigger subject of using a C compiler for a PIC.  I have
been coding in C for 15 years and most of my code I write daily is in C.  I
would LOVE to write C code for a PIC but cannot get over the feeling that I
am doing the wrong thing.  Believe me, after writing a large application
for a 17C44 in assembly language, I really want to use C.  Compilers
without an available stack tend to use large blocks of RAM and overhead
routines to access them as pseudo stack spaces, and I think this is
wasteful in a PIC.  Most PICs I use have a rather small amount of RAM to
start with.  The day a PIC has an addressable stack will be when everything
changes.  Maybe for simple applications where there is sufficient memory, a
compiler would be great.  But then again, if the application is simple, why
not just code it in assembly language?  My answer to that would be because
I make less mistakes in C and can write code a lot faster.  Any other thoughts?