Probably true (I think all x64 hardware includes SSE at least), but they did imply they were trying to use just the scalar instructions. (They also said no hand

Probably true (I think all x64 hardware includes SSE at least), but they did imply they were trying to use just the scalar instructions. (They also said no hand-assembly, but something like: register uint64_t ra,rd,... ra += 0xFFFFFFFF&r8 rd += r8 >> 32 should accomplish much the same thing given a resonably well-developed compiler.)