SIZE_B
#define GETARG_B(i) getarg(i, POS_B, SIZE_B)
#define SETARG_B(i,v) setarg(i, v, POS_B, SIZE_B)
#define BITRK (1 << (SIZE_B - 1))
#define SIZE_Bx (SIZE_C + SIZE_B)
#define SIZE_Ax (SIZE_C + SIZE_B + SIZE_A)
#define MAXARG_B ((1<<SIZE_B)-1)