use _udiv128 for divUint on msvc 2019

include/mcl/vint.hpp

@@ -150,7 +150,7 @@ inline uint32_t divUnit(uint32_t *pr, uint32_t H, uint32_t L, uint32_t y)
 #if MCL_SIZEOF_UNIT == 8
 inline uint64_t divUnit(uint64_t *pr, uint64_t H, uint64_t L, uint64_t y)
 {
-#if defined(MCL_VINT_64BIT_PORTABLE)
+#if defined(MCL_VINT_64BIT_PORTABLE) || (defined(_MSC_VER) && _MSC_VER < 1920)
 	uint32_t px[4] = { uint32_t(L), uint32_t(L >> 32), uint32_t(H), uint32_t(H >> 32) };
 	uint32_t py[2] = { uint32_t(y), uint32_t(y >> 32) };
 	size_t xn = 4;
@@ -162,7 +162,7 @@ inline uint64_t divUnit(uint64_t *pr, uint64_t H, uint64_t L, uint64_t y)
 	*pr = make64(r[1], r[0]);
 	return make64(q[1], q[0]);
 #elif defined(_MSC_VER)
-	#error "divUnit for uint64_t is not supported"
+	return _udiv128(H, L, y, pr);
 #else
 	typedef __attribute__((mode(TI))) unsigned int uint128;
 	uint128 t = (uint128(H) << 64) | L;

test/vint_test.cpp

@@ -9,6 +9,7 @@
 #include <cybozu/xorshift.hpp>
 #ifndef MCL_USE_VINT
 #include <gmpxx.h>
+#include <cybozu/link_mpir.hpp>
 #endif
 
 #define PUT(x) std::cout << #x "=" << x << std::endl;