On 06/05/2011 13:29, Olin Lathrop wrote:
> Really?  I have heard of JAL being referred to as a "compiler" many times=
,
> and it supposedly uses GCC on Unix systems.
The JAL source is compiled to p-Code
The p-code is translated or compiled  to PIC Assembler at "Compile time"=20
There is no run time "engine".

On 16F87x the real HW stack usage does increase from 50% to 75% if a=20
Procedure call is done in an ISR (JAL, some C compilers for PIC don't=20
allow Function call at all in an ISR) . But the Stack isn't being used=20
for Parameters like on Z80 or x86 implementations of C.


 >
 >No, the stack is used for all return addresses, whether they be as a=20
result
 >of a interrupt or a explicit call.
 >
That's an implementation dependency.  It's possible to implement a SW=20
stack for even recursion / nested calls etc, threads etc and only use=20
the HW stack for ISR return..

The older PIC certainly can't use the HW stack to pass paramenters or=20
return them. Some have very limited HW stack.


There is of course a large grey area of  High Level Languages that have=20
some compiling and mostly run time Interpretor (runtime per block=20
compile or P-code virtual machine) to systems with "some" run time=20
support and interpretation to C, C++ and Modula-2 systems with zero run=20
time system and just 100% compile to native.


--=20
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