User manual

mikroPascal PRO for dsPIC30/33 and PIC24
MikroElektronika
197
In the First_Unit we will dene and declare routine called pi_r_squared (calculates pi multiplied by the radius
squared):
unit First_Unit;
procedure pi_r_squared(rr : real); // Declaration of the pi_r_squared routine
implementation
procedure pi_r_squared(rr : real); // Denition of the pi_r_squared routine
var res : real;
begin
res := rr*3.14;
end;
end.
In the Second_Unit we will make a call to the routines dened externally (r_squared and pi_r_squared). First of
all, we must declare their prototypes followed with a external modier. Then, we can proceed to the routine call :
unit Second_Unit;
procedure CircleArea();
function r_squared(r : real) : real; external; // Declaration of the r_squared routine
(dened in Main_Unit) followed with a external modier
procedure pi_r_squared(rr : real); external; // Declaration of the pi_r_squared routine
(dened in First_Unit) followed with a external modier
implementation
procedure CircleArea(); // Denition of the CircleArea routine
var res : real;
begin
res := r_squared(5); // r_squared routine call
pi_r_squared(res); // pi_r_squared routine call
end;
end.
Variables and dsPIC30/33 and PIC24
Every declared variable consumes part of RAM memory. Data type of variable determines not only the allowed range
of values, but also the space a variable occupies in RAM memory. Bear in mind that operations using different types
of variables take different time to be completed. mikroPascal PRO for dsPIC30/33 and PIC24 recycles local variable
memory space – local variables declared in different functions and procedures share the same memory space, if
possible.
There is no need to declare SFRs explicitly, as mikroPascal PRO for dsPIC30/33 and PIC24 automatically declares
relevant registers as global variables of volatile word see SFR for details.