ALIGN(v, a) ARRAY_SIZE() #define ARRAY_SIZE(arr) (sizeof(arr)/sizeof(arr[0])) Macro to compute the size of the static array arr . Parameters arr static array ALIGN() #define ALIGN(v, a) (((v) + (a)-1) & ~((a)-1)) Macro to align a value v to a specified unit a . Parameters v value to be aligned a alignment unit in bytes ALIGN_DOWN() #define ALIGN_DOWN(x, a) ALIGN((x) - ((a) - 1), (a)) Macro to align down a value v to a specified unit a . Parameters v value to be aligned down a alignment unit in bytes