Mikroelektronika MIKROE-742 데이터 시트

program Example;

type TMyFunctionType = function (param1, param2: byte; param3: word)

: word;  // First, define the procedural type

MyPtr: ^TMyFunctionType;

// This is a pointer to previously defined type

Sample: word;

Func1(p1, p2: byte; p3: word): word;// Now, define few

functions which will be pointed to. Make sure that parameters match
the type definition 

result := p1 

and p2 or p3;                // return something

function Func2(abc: byte; def: byte; ghi: word): word;     // Another

function of the same kind. Make sure that parameters match the type
definition  

result := abc * def + ghi;                  // return something

function Func3(first, yellow: byte; monday: word): word// Yet anoth-

er function. Make sure that parameters match the type definition   

result := monday - yellow - first;          // return something

//  main program:
begin

MyPtr  := @Func1;                ,// MyPtr now points to Func1

Sample := MyPtr^(1, 2, 3);       // Perform function call via

pointer, call Func1, the return value is 3

MyPtr  := @Func2;                 // MyPtr now points to Func2

Sample := MyPtr^(1, 2, 3);       // Perform function call via

pointer, call Func2, the return value is 5

MyPtr  := @Func3;                 // MyPtr now points to Func3

Sample := MyPtr^(1, 2, 3);        // Perform function call via

pointer, call Func3, the return value is 0

The 

@

operator returns the address of a variable or routine, i.e. 

@

constructs a point-

er to its operand. The following rules are applied to 

@

:

- If X is a variable, 

@X

returns the address of 

X

. 

- If 

F

is a routine (a function or procedure), 

@F

returns F’s entry point (the result is of 

longint

). 

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- SOFTWARE AND HARDWARE SOLUTIONS FOR EMBEDDED WORLD

CHAPTER 5