/* f is 9.23 fixed point, other differences are 4.28 fixed point.  */
static void fd_fixed_fwd(int32_t f[4])
/* f is 9.23 fixed point, other differences are 4.28 fixed point.  */
static void fd_fixed_fwd(int32_t f[4])
{
    f[0] += (f[1] >> 5) + ((f[1] >> 4) & 1);
    f[1] += f[2];
    f[2] += f[3];
}