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

Additional C Pointer Types
} else {
fprintf(stderr,"I don't know how to access memory space: %d\n",
memory_space);
}
}
These functions work in a similar fashion:
• if accessing bit_memory, then
- determine the correct byte offset and bit offset
- read or write the appropriate place in the real_bit_memory
• otherwise access another memory (whose access is unknown)
With the two major pieces of the puzzle in place, generate some variables and
accesses:
__external__ unsigned char bits[NUMBER_OF_BITS]
__attribute__((space(external(bit_memory))));
// inside main
__external__ unsigned char *bit;
bit = bits;
for (i = 0; i < 512; i++) {
printf("%d ",*bit++);
}
Apart from the __external__ CV-qualifiers, ordinary C statements can be used to
define and access variables in the external memory space.
© 2008 Microchip Technology Inc. DS51284H-page 89