gcc-you can use this code to learn something about gcc, and inquire further into linux,

				f (unsigned short Z[48])				{				  int j;				  unsigned short t1, t2, t3, T[48];				  unsigned short *p = T + 48;								  for (j = 1; j < 8; j++)				    {				      t1 = *Z++;				      *--p = *Z++;				      *--p = t1;				      t1 = inv(*Z++);				      t2 = -*Z++;				      t3 = -*Z++;				      *--p = inv(*Z++);				      *--p = t2;				      *--p = t3;				      *--p = t1;				    }				}