4.9 data_alignment Pragma

The IAR data_alignment pragma controls the memory alignment of the variable immediately following.

Suggested Replacement

There is no equivalent MPLAB XC8 pragma, but there is an attribute that performs a similar task.

The MPLAB XC8 aligned(n) attribute aligns the qualified object’s address with the next address that is a whole multiple of the numerical value n. If the CCI is enabled, a more portable macro, __align(n) (note the different spelling), is available. This attribute works with automatic as well as static storage duration objects.

Caveats

Note that the aligned attribute is used to increase the alignment of a variable, not reduce it. To decrease the alignment value of a variable, use the packed attribute.

Examples

Consider migrating IAR code such as:

#pragma data_alignment=4
char marker = 3;

to MPLAB XC8 code similar to:

char marker __attribute__((aligned(4))) = 3;

Further Information

See the Attributes section in the MPLAB XC8 C Compiler User's Guide for AVR MCUs for more information on this attribute.