bswap64
#define htobe64(x) bswap64((x))
#define be64toh(x) bswap64((x))
#define htole64(x) bswap64((x))
#define le64toh(x) bswap64((x))
case 64: expr->value = bswap64(val); break;
unsigned long long bswap64(void);