求问: 关于取模

unsigned a1=0,a2=0,a3=0;
	for(unsigned i=1;i<=m;i++)
		a1+=s2[i],a2^=s2[i]*i,a3+=s2[i]*i;

const long long mod = (1ll << 32);
long long res1 = 0,res2 = 0,res3 = 0;
	for (int i = 1;i <= m;++i) res1 = (res1 + f[i]) % mod,res2 ^= (1ll * f[i] * i),res3 = (res3 + (f[i] * i % mod)) % mod;