Add JNI backend for Spark SQL function conv for (hexa)decimals

src/main/cpp/src/CastStringJni.cpp

@@ -15,6 +15,7 @@
  */
 
 #include "cast_string.hpp"
+#include <cudf/strings/convert/convert_integers.hpp>
 
 #include "cudf_jni_apis.hpp"
 #include "dtype_utils.hpp"
@@ -111,4 +112,46 @@ JNIEXPORT jlong JNICALL Java_com_nvidia_spark_rapids_jni_CastStrings_fromDecimal
   }
   CATCH_CAST_EXCEPTION(env, 0);
 }
+
+JNIEXPORT jlong JNICALL Java_com_nvidia_spark_rapids_jni_CastStrings_changeRadix(
+  JNIEnv* env, jclass, jlong input_column, jint fromRadix, jint toRadix)
+{
+  JNI_NULL_CHECK(env, input_column, "input column is null", 0);
+
+  try {
+    cudf::jni::auto_set_device(env);
+
+    cudf::column_view cv{*reinterpret_cast<cudf::column_view const*>(input_column)};
+    auto const uint64_cv = [&] {
+      switch (fromRadix) {
+        case 10: {
+          return spark_rapids_jni::string_to_integer(cudf::data_type(cudf::type_id::UINT64),
+                                                     cv,
+                                                     JNI_FALSE,
+                                                     JNI_TRUE,
+                                                     cudf::get_default_stream());
+        } break;
+        case 16: {
+          return cudf::strings::hex_to_integers(cv, cudf::data_type(cudf::type_id::UINT64));
+        }
+      }
+      return std::unique_ptr<cudf::column>(nullptr);
+    }();
+
+    std::unique_ptr<cudf::column> result_col = [&] {
+      switch (toRadix) {
+        case 16: {
+          return cudf::strings::integers_to_hex(*uint64_cv);
+        } break;
+        case 10: {
+          return cudf::strings::from_integers(*uint64_cv);
+        } break;
+      }
+      return std::unique_ptr<cudf::column>(nullptr);
+    }();
+
+    return cudf::jni::release_as_jlong(result_col);
+  }
+  CATCH_CAST_EXCEPTION(env, 0);
+}
 }

src/main/java/com/nvidia/spark/rapids/jni/CastStrings.java

@@ -82,7 +82,7 @@ public static ColumnVector toDecimal(ColumnView cv, boolean ansiMode, boolean st
 
   /**
    * Convert a decimal column to a string column.
-   * 
+   *
    * @param cv the column data to process
    * @return the converted column
    */
@@ -102,10 +102,16 @@ public static ColumnVector toFloat(ColumnView cv, boolean ansiMode, DType type)
     return new ColumnVector(toFloat(cv.getNativeView(), ansiMode, type.getTypeId().getNativeId()));
   }
 
+
+  public static ColumnVector changeRadix(ColumnView cv, int fromRadix, int toRadix) {
+    return new ColumnVector(changeRadix(cv.getNativeView(), fromRadix, toRadix));
+  }
+
   private static native long toInteger(long nativeColumnView, boolean ansi_enabled, boolean strip,
       int dtype);
   private static native long toDecimal(long nativeColumnView, boolean ansi_enabled, boolean strip,
       int precision, int scale);
   private static native long toFloat(long nativeColumnView, boolean ansi_enabled, int dtype);
   private static native long fromDecimal(long nativeColumnView);
+  private static native long changeRadix(long nativeColumnView, int fromRadix, int toRadix);
 }