User manual

mikroPascal PRO for PIC32
MikroElektronika
205
var ptr1: ^const byte; // ptr1 pointer in data space pointing to a
byte in code space
var ptr2: ^const ^volatile sfr byte; rx; // ptr2 is pointer in rx space pointing to a
pointer in code space pointing to volatile byte in sfr space
var ptr3: ^data byte; code; // error, pointers can not be placed in code
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Due to backward compatibility, pointers to program memory space can also be declared within constant declaration
block (using keyword const):
program const_ptr;
// constant array will be stored in program memory
const b_array: array[5] of byte = (1,2,3,4,5);
const ptr: ^byte; // ptr is pointer to program memory space
begin
ptr := @b_array; // ptr now points to b_array[0]
PORTA := ptr^;
ptr := ptr + 3; // ptr now points to b_array[3]
PORTA := ptr^;
end.
This leads to equality of the following declarations:
var ptr1 : ^const byte; // ptr1 pointer in data space pointing to a byte in code
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const ptr2 : ^byte; // ptr2 pointer in data space pointing to a byte in code
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Therefore, when declaring a pointer within constant declaration block, const qualier refers to pointed object, not to
pointer itself.
Notes :
- Pointer to constant space (Flash memory) is allocated in RAM.
- Constants of a simple type are not allocated in the Flash memory nor in RAM, but changed in the compile time, and
therefore address of a such constant can not be obtained.
Function Pointers
Function pointers are allowed in mikroPascal PRO for PIC32. The example shows how to dene and use a function
pointer:
Example:
Example demonstrates the usage of function pointers. It is shown how to declare a procedural type, a pointer to
function and nally how to call a function via pointer.