5.16 __load_program_memory Intrinsic Function

The IAR __load_program_memory intrinsic function reads one byte from the specified code memory within the lower 64kB of program memory.

Suggested Replacement

There is no MPLAB XC8 equivalent built-in function; however, library functions and plain C code can perform a similar task.

Use the pgm_read_byte() function to read a byte of program memory.

Alternatively, cast the address to a const __flash unsigned char * pointer and dereference it in the usual way.

Caveats

The pgm_read_byte() function takes an integer argument, not a pointer.

Examples

Consider migrating IAR code such as:

volatile unsigned char val;
__flash unsigned char myVar = 0x55;

void foo(void) {
  unsigned char __flash * dp = &myVar;
  val = __load_program_memory(dp);
}

to MPLAB XC8 code similar to:

#include <avr/pgmspace.h>
const __flash myVar = 0x55;

int main(void)
{
  unsigned char val;
  val = pgm_read_byte(&myVar);
}

Further Information

See the Library Functions and Special Type Qualifiers sections in the MPLAB XC8 C Compiler User's Guide for AVR MCUs for more information on the library function and qualifier.