Mikroelektronika MIKROE-724 データシート

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mikoBasic PRO for dsPIC30/33 and PIC24

MikroElektronika

Pointers and memory spaces

Pointers can point to data in any available memory space. 

Pointers can reside in any available memory space except in program (code) memory space.

dim ptr1 as ^const byte  ‘ ptr1 pointer in data space pointing to a byte in code space

dim ptr2 as ^const ^volatile sfr byte rx ‘ ptr2 is pointer in rx space pointing to a 

dim ptr3 as ^data byte code   ‘ error, pointers can not be placed in code space

Due to backward compatibility, pointers to program memory space can also be declared within constant declaration 

block (using keyword 

const

):

program const_ptr

const b_array as byte[5] = (1,2,3,4,5)

const ptr as ^byte     ‘ ptr is pointer to program memory space

main:

  ptr   = @b_array     ‘ ptr now points to b_array[0]

  PORTA = ptr^

  ptr   = ptr + 3      ‘ ptr now points to b_array[3]

  PORTA = ptr

This leads to equality of the following declarations:

dim      ptr1  as  ^const  byte    ‘  ptr1  pointer  in  data  space  pointing  to  a byte in  code 

const ptr1 as ^byte ‘ ptr1 pointer in data space pointing to a byte in code space

Therefore, when declaring a pointer within constant declaration block, const qualifier 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 mikroBasic PRO for dsPIC30/33 and PIC24. The example shows how to define and 

use a function pointer: