Mikroelektronika MIKROE-724 データシート

mikroBasic PRO for dsPIC30/33 and PIC24

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In addition to the standard storage qualifiers(

const, volatile

) the compiler introduces storage qualifiers of 

near 

and

 far.

Near Memory Qualifier

 

1. 

 

    The qualifier 

near

 is used to denote that a variable is allocated in near data space (the first 8 kB of Data  

 

    memory). Such variables can sometimes be accessed more efficiently than variables not allocated (or not  

 

    known to be allocated) in near data space. 

 

    If variables are allocated in the near data section, the compiler is often able to generate better (more  

 

    compact) code than if the variables are not allocated in the near data section.

 

2. 

Program Memory Objects 

 

    The qualifier 

near

 is used to denote that a constant is allocated in the default program memory page  

 

    (32kB segment of program memory). Default program memory page is the one with most free space and  

 

    is set by the compiler by analyzing program memory pages. 

 

    This qualifier is set as default by the compiler, if no other qualifier is used.

Far Memory Qualifier

 

1 

 

 The qualifier 

far

 is used to denote that a variable will not be in near data space (i.e. the variable can be  

 

 located  anywhere in data memory). This qualifier is set as default by the compiler, if no other qualifier is  

 

 used.

 

2. 

Program Memory Objects 

 

 The qualifier 

far

 is used to denote that a constant can be allocated anywhere in the program memory, in  

 

 the page pointed to by PSVPAG register.

near

First 8 kB of RAM

In default page

far

Anywhere in RAM

In page pointed to PSVPAG register

Example: 

dim i as char  ‘ far memory qualifier is set, variable i can allocated somewhere in data memory

dim j as char near ‘ near memory qualifier is set, variable j will be allocated in the 

const k as longint = 10000  ‘ near memory qualifier is set, constant k will be allocated 

Related topics: dsPIC Memory Organization, dsPIC Memory Type Specifiers