MPLAB C Compiler for PIC24 MCUs and dsPIC DSCs ... - Microchip

16-Bit C Compiler User’s Guide
D.13 PRAGMAS
The PIC18 MCU Compiler uses pragmas for sections (code, romdata, udata,
idata), interrupts (high-priority and low-priority) and variable locations (bank, section).
The 16-Bit Device Compiler uses non-ANSI attributes instead of pragmas.
TABLE D-5: PRAGMAS VS. ATTRIBUTES
Pragma (PIC18 MCU Compiler) Attribute (16-Bit Device Compiler)
#pragma udata [name] __attribute__ ((section ("name")))
#pragma idata [name] __attribute__ ((section ("name")))
#pragma romdata [name] __attribute__ ((space (prog)))
#pragma code [name] __attribute__ ((section ("name"))),
__attribute__ ((space (prog)))
#pragma interruptlow __attribute__ ((interrupt))
#pragma interrupt __attribute__ ((interrupt, shadow))
#pragma varlocate bank NA*
#pragma varlocate name
*16-bit devices do not have banks.
NA*
EXAMPLE D-4: SPECIFY AN UNINITIALIZED VARIABLE IN A USER SECTION
IN DATA MEMORY
PIC18 #pragma udata mybss
int gi;
16-Bit int __attribute__((__section__(".mybss"))) gi;
EXAMPLE D-5: LOCATE THE VARIABLE MABONGA AT ADDRESS 0X100 IN
DATA MEMORY
PIC18 #pragma idata myDataSection=0x100;
int Mabonga = 1;
16-Bit int __attribute__((address(0x100))) Mabonga = 1;
EXAMPLE D-6: SPECIFY A VARIABLE TO BE PLACED IN PROGRAM
MEMORY
PIC18 #pragma romdata const_table
const rom char my_const_array[10] =
{0,1,2,3,4,5,6,7,8,9};
16-Bit const __attribute__((space(auto_psv)))
char my_const_array[10] = {0,1,2,3,4,5,6,7,8,9};
Note: The 16-Bit Device Compiler does not directly support accessing variables
in program space. Variables so allocated must be explicitly accessed by the
programmer, usually using table-access inline assembly instructions, or
using the program space visibility window. See Section 4.14 “Program
Space Visibility (PSV) Usage” for more on the PSV window.
DS51284H-page 206 © 2008 Microchip Technology Inc.