gf128_read
a = gf128_add(r, gf128_read(&v[0*16]));
b = gf128_read(&v[1*16]);
c = gf128_read(&v[2*16]);
d = gf128_read(&v[3*16]);
v = gf128_add(v, gf128_read(&buf[0]));
a = gf128_add(agc->hash, gf128_read(enccntr));
h = gf128_read(hbuf);
v = gf128_add(v, gf128_read(data));