How many byte alignment for arm?

Question

I am programming C on a arm cortex cpu with gcc-arm-none-eabi. I know it is 4-byte alignment by test and google.

But is there any macro or variable which defines how many bytes alignment it is? I need know in case someday this program may be port for another cpu.

Answer 1

A trick to find the alignment of a particular data type is to pack it in a struct with a char:

#define LONG_ALIGNMENT (sizeof (struct {char a, long b}) - sizeof (long))
#define INT_ALIGNMENT  (sizeof (struct {char a, int b}) - sizeof (int))