Zilog Z8F0130 - Manual (Page 226)

Using the ANSI C-Compiler UM013037-1212
202
Zilog Developer Studio II – Z8 Encore!
User Manual
return 1;

return ( k * recursive_fn (k-1));

}
When the static call frame option is selected, all call frames are assumed static by the com-
piler unless the
reentrant storage class is used in the function declaration. Obviously, if
large numbers of functions in an application must be declared reentrant, the benefit of
using static frames diminishes proportionately.
When the dynamic call frame option is selected, all call frames are assumed reentrant by
the compiler.
Interrupt Support
To support interrupts, the Z8 Encore! C-Compiler provides the following features:
•
interrupt Keyword – see page 202
•
Interrupt Vector Setup – see page 202
interrupt Keyword
Functions that are preceded by #pragma interrupt or are associated with the interrupt
storage class are designated as interrupt handlers. These functions should neither take
parameters nor return a value. The compiler stores the machine state at the beginning of
these functions and restores the machine state at the end of these functions. Also, the com-
piler uses the
iret instruction to return from these functions.
For example:
void interrupt isr_timer0(void)

{

}
or
#pragma interrupt

void isr_timer0(void)

{

}
Interrupt Vector Setup
The compiler provides two mechanisms for interrupt vector setup:
•
SET_VECTOR Intrinsic Function – see page 203
•
_At Keyword – see page 203