constant_time_eq_int
((BN_ULONG)0 - (constant_time_eq_int(j,idx)&1));
y0 = (BN_ULONG)0 - (constant_time_eq_int(i,0)&1);
y1 = (BN_ULONG)0 - (constant_time_eq_int(i,1)&1);
y2 = (BN_ULONG)0 - (constant_time_eq_int(i,2)&1);
y3 = (BN_ULONG)0 - (constant_time_eq_int(i,3)&1);
& ((BN_ULONG)0 - (constant_time_eq_int(j,idx)&1));
static inline unsigned int constant_time_eq_int(int a, int b);