blockmix_salsa8
blockmix_salsa8(X, Y, Z, r);
blockmix_salsa8(Y, X, Z, r);
blockmix_salsa8(X, Y, Z, r);
blockmix_salsa8(Y, X, Z, r);
static void blockmix_salsa8(const uint32_t *, uint32_t *, uint32_t *, size_t);