Test test utils printing

test/catch2_test_printing.cu

@@ -0,0 +1,36 @@
+#include "test_util.h"
+
+#include "catch2_test_helper.h"
+
+template <typename T>
+std::string print(T val) 
+{
+  std::stringstream ss;
+  ss << val;
+  return ss.str();
+}
+
+#if CUB_IS_INT128_ENABLED
+TEST_CASE("Test utils can print __int128", "[test][utils]")
+{
+  REQUIRE( print(__int128_t{0}) == "0" );
+  REQUIRE( print(__int128_t{42}) == "42" );
+  REQUIRE( print(__int128_t{-1}) == "-1" );
+  REQUIRE( print(__int128_t{-42}) == "-42" );
+  REQUIRE( print(__int128_t{-1} << 120) == "-1329227995784915872903807060280344576" );
+}
+
+TEST_CASE("Test utils can print __uint128", "[test][utils]")
+{
+  REQUIRE( print(__uint128_t{0}) == "0" );
+  REQUIRE( print(__uint128_t{1}) == "1" );
+  REQUIRE( print(__uint128_t{42}) == "42" );
+  REQUIRE( print(__uint128_t{1} << 120) == "1329227995784915872903807060280344576" );
+}
+#endif
+
+TEST_CASE("Test utils can print KeyValuePair", "[test][utils]")
+{
+  REQUIRE( print(cub::KeyValuePair<int, int>{42, -42}) == "(42,-42)" );
+}
+

test/test_util.h

@@ -733,14 +733,14 @@ static std::ostream& operator<<(std::ostream& os, __uint128_t val)
 {
   constexpr int max_digits = 40;
   char buffer[max_digits] = {};
-  char* digit = buffer + max_digits - 1;
+  char* digit = buffer + max_digits;
   const char* ascii = "0123456789";
 
   do 
   {
+    digit--;
     *digit = ascii[val % 10];
     val /= 10;
-    digit--;
   }
   while(val != 0);