jni: Add platform-private convenience headers

Add macros to simplify registration of both regular and @FastNative JNI
functions.

Bug: 34955272
Change-Id: If07dbd82452a28de6dcea978d46b4805d1f0eeea

2 files changed, 85 insertions, 1 deletions

diff --git a/Android.bp b/Android.bp
index bf35ebf..fe073d8 100644
--- a/Android.bp
+++ b/Android.bp
@@ -41,7 +41,7 @@ cc_library {
         "-Werror",
         "-fvisibility=protected",
     ],
-    export_include_dirs: ["include"],
+    export_include_dirs: ["include", "platform_include"],
 }
 
 //
diff --git a/platform_include/nativehelper/jni_macros.h b/platform_include/nativehelper/jni_macros.h
new file mode 100644
index 0000000..b628bf7
--- /dev/null
+++ b/platform_include/nativehelper/jni_macros.h
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * JNI helper macros.
+ *
+ * Only intended to be used in the platform.
+ */
+
+#ifndef NATIVEHELPER_JNI_MACROS_H
+#define NATIVEHELPER_JNI_MACROS_H
+
+
+// Intended to construct a JNINativeMethod.
+//   (Assumes the C name is the ClassName_JavaMethodName).
+#ifndef NATIVE_METHOD
+#define NATIVE_METHOD(className, functionName, signature)                \
+  { #functionName,                                                       \
+    signature,                                                           \
+    _NATIVEHELPER_JNI_MACRO_CAST(void*) (className ## _ ## functionName) \
+  }
+#endif
+
+// Intended to construct a JNINativeMethod (when the C name doesn't match the Java name).
+//   (Assumes the C name is the ClassName_Identifier).
+#ifndef OVERLOADED_NATIVE_METHOD
+#define OVERLOADED_NATIVE_METHOD(className, functionName, signature, identifier) \
+  { #functionName,                                                               \
+    signature,                                                                   \
+    _NATIVEHELPER_JNI_MACRO_CAST(void*) (className ## _ ## identifier)           \
+  }
+#endif
+
+// Used for methods that are annotated with @FastNative on the managed side.
+//   See NATIVE_METHOD for usage.
+#ifndef FAST_NATIVE_METHOD
+#define FAST_NATIVE_METHOD(className, functionName, signature)           \
+  { #functionName,                                                       \
+    signature,                                                           \
+    _NATIVEHELPER_JNI_MACRO_CAST(void*) (className ## _ ## functionName) \
+  }
+#endif
+
+// Used for methods that are annotated with @FastNative on the managed side,
+//   and when the C-name doesn't match the Java-name.
+//
+//   See OVERLOADED_NATIVE_METHOD for usage.
+#ifndef OVERLOADED_FAST_NATIVE_METHOD
+#define OVERLOADED_FAST_NATIVE_METHOD(className, functionName, signature, identifier) \
+  { #functionName,                                                                    \
+    signature,                                                                        \
+    _NATIVEHELPER_JNI_MACRO_CAST(void*) (className ## _ ## identifier)                \
+  }
+#endif
+
+////////////////////////////////////////////////////////
+//                IMPLEMENTATION ONLY.
+//                DO NOT USE DIRECTLY.
+////////////////////////////////////////////////////////
+
+
+// C-style cast for C, C++-style cast for C++ to avoid warnings/errors.
+#if defined(__cplusplus)
+#define _NATIVEHELPER_JNI_MACRO_CAST(to) \
+    reinterpret_cast<to>
+#else
+#define _NATIVEHELPER_JNI_MACRO_CAST(to) \
+    (to)
+#endif
+
+#endif