Mikroelektronika MIKROE-742 데이터 시트

Functions and procedures, collectively referred to as routines, are subprograms
(self-contained statement blocks) which perform a certain task based on a number
of input parameters. When executed, a function returns a value while procedure
does not.

mikroPascal PRO for AVR does not support inline routines.

A function is declared like this:

function function_name(parameter_list) : return_type;

{ local declarations }

{ function body }

function_name

represents a function’s name and can be any valid identifier.

return_type

is a type of return value and can be any simple type. Within parenthe-

ses,

parameter_list

is a formal parameter list very similar to variable declaration.

In Pascal, parameters are always passed to a function by the value — to pass an
argument by address, add the keyword 

var 

ahead of identifier.

Local declarations

are optional declarations of variables and/or constants, local

for the given function. 

Function body

is a sequence of statements to be executed

upon calling the function.

A function is called by its name, with actual arguments placed in the same sequence
as their matching formal parameters. The compiler is able to coerce mismatching
arguments to the proper type according to implicit conversion rules. Upon a function
call, all formal parameters are created as local objects initialized by values of actu-
al arguments. Upon return from a function, a temporary object is created in the place
of the call and it is initialized by the value of the function result. This means that func-
tion call as an operand in complex expression is treated as the function result.

In standard Pascal, a 

function_name

is automatically created local variable that

can be used for returning a value of a function. mikroPascal PRO for AVR also
allows you to use the automatically created local variable result to assign the return
value of a function if you find function name to be too ponderous. If the return value
of a function is not defined the compiler will report an error.

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- SOFTWARE AND HARDWARE SOLUTIONS FOR EMBEDDED WORLD

CHAPTER 5