NLIMBS
#define NLIMBS (64 / sizeof(word_t))
#define NLIMBS 4
typedef limb felem[NLIMBS];
typedef limb longfelem[NLIMBS * 2];
typedef u64 smallfelem[NLIMBS];
#define NLIMBS 7
typedef limb felem[NLIMBS];
typedef widelimb widefelem[2 * NLIMBS - 1];
#define NLIMBS 9
typedef limb felem[NLIMBS];
typedef uint128_t largefelem[NLIMBS];