+# elif (defined(_M_AMD64) || defined(_M_X64)) && defined(SIXTY_FOUR_BIT)
+# if defined(_MSC_VER) && _MSC_VER>=1400
+ unsigned __int64 __umulh (unsigned __int64 a,unsigned __int64 b);
+ unsigned __int64 _umul128 (unsigned __int64 a,unsigned __int64 b,
+ unsigned __int64 *h);
+# pragma intrinsic(__umulh,_umul128)
+# define BN_UMULT_HIGH(a,b) __umulh((a),(b))
+# define BN_UMULT_LOHI(low,high,a,b) ((low)=_umul128((a),(b),&(high)))
+# endif
+# elif defined(__mips) && (defined(SIXTY_FOUR_BIT) || defined(SIXTY_FOUR_BIT_LONG))
+# if defined(__GNUC__) && __GNUC__>=2
+# if __GNUC__>=4 && __GNUC_MINOR__>=4 /* "h" constraint is no more since 4.4 */
+# define BN_UMULT_HIGH(a,b) (((__uint128_t)(a)*(b))>>64)
+# define BN_UMULT_LOHI(low,high,a,b) ({ \
+ __uint128_t ret=(__uint128_t)(a)*(b); \
+ (high)=ret>>64; (low)=ret; })
+# else
+# define BN_UMULT_HIGH(a,b) ({ \
+ register BN_ULONG ret; \
+ asm ("dmultu %1,%2" \
+ : "=h"(ret) \
+ : "r"(a), "r"(b) : "l"); \
+ ret; })
+# define BN_UMULT_LOHI(low,high,a,b)\
+ asm ("dmultu %2,%3" \
+ : "=l"(low),"=h"(high) \
+ : "r"(a), "r"(b));
+# endif
+# endif