cutils: add OS-independent endian.h

cutils/endian.h provides the helpers defined in endian(3), either by
pulling in the OS's built-in endian.h (where available) or recreating
them using GCC builtins.

Change-Id: Ic8965f67e1efdc03f884dbe6b7fe0276f840e4fc
Signed-off-by: Greg Hackmann <ghackmann@google.com>

3 files changed, 113 insertions, 0 deletions

diff --git a/include/cutils/endian.h b/include/cutils/endian.h
new file mode 100644
index 0000000..3d27ce6
--- /dev/null
+++ b/include/cutils/endian.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#ifndef __CUTILS_ENDIAN_H
+#define __CUTILS_ENDIAN_H
+
+#if defined(__linux__) && !defined(TEST_CUTILS_ENDIAN_H)
+#include <endian.h>
+#else
+
+#if !defined(__BYTE_ORDER__)
+/* gcc and clang predefine __BYTE_ORDER__, so this should never happen */
+#error Compiler does not define __BYTE_ORDER__
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#define htobe16(x)  (x)
+#define htobe32(x)  (x)
+#define htobe64(x)  (x)
+#define htole16(x)  __builtin_bswap16(x)
+#define htole32(x)  __builtin_bswap32(x)
+#define htole64(x)  __builtin_bswap64(x)
+#else
+#define htobe16(x)  __builtin_bswap16(x)
+#define htobe32(x)  __builtin_bswap32(x)
+#define htobe64(x)  __builtin_bswap64(x)
+#define htole16(x)  (x)
+#define htole32(x)  (x)
+#define htole64(x)  (x)
+#endif /* __BYTE_ORDER__ */
+
+#define be16toh(x)  htobe16(x)
+#define le16toh(x)  htole16(x)
+#define be32toh(x)  htobe32(x)
+#define le32toh(x)  htole32(x)
+#define be64toh(x)  htobe64(x)
+#define le64toh(x)  htole64(x)
+
+#endif /* defined(__linux__) */
+
+#endif /* __CUTILS_ENDIAN_H */
diff --git a/libcutils/tests/Android.mk b/libcutils/tests/Android.mk
index cf70345..577b61d 100644
--- a/libcutils/tests/Android.mk
+++ b/libcutils/tests/Android.mk
@@ -16,6 +16,7 @@ LOCAL_PATH := $(call my-dir)
 
 test_src_files := \
     test_str_parms.cpp \
+    EndianTest.cpp
 
 test_target_only_src_files := \
     MemsetTest.cpp \
diff --git a/libcutils/tests/EndianTest.cpp b/libcutils/tests/EndianTest.cpp
new file mode 100644
index 0000000..a484da7
--- /dev/null
+++ b/libcutils/tests/EndianTest.cpp
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#include <stdint.h>
+
+#define TEST_CUTILS_ENDIAN_H
+#include <cutils/endian.h>
+#include <gtest/gtest.h>
+
+static const uint16_t host16 = 0x1122;
+static const uint32_t host32 = 0x11223344;
+static const uint64_t host64 = 0x1122334455667788;
+static const uint16_t swapped16 = 0x2211;
+static const uint32_t swapped32 = 0x44332211;
+static const uint64_t swapped64 = 0x8877665544332211;
+#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+static const uint16_t le16 = swapped16;
+static const uint32_t le32 = swapped32;
+static const uint64_t le64 = swapped64;
+static const uint16_t be16 = native16;
+static const uint32_t be32 = native32;
+static const uint64_t be64 = native64;
+#else
+static const uint16_t le16 = host16;
+static const uint32_t le32 = host32;
+static const uint64_t le64 = host64;
+static const uint16_t be16 = swapped16;
+static const uint32_t be32 = swapped32;
+static const uint64_t be64 = swapped64;
+#endif
+
+TEST(endian, endian) {
+    EXPECT_EQ(le16, htole16(host16));
+    EXPECT_EQ(host16, le16toh(htole16(host16)));
+    EXPECT_EQ(be16, htobe16(host16));
+    EXPECT_EQ(host16, be16toh(htobe16(host16)));
+
+    EXPECT_EQ(le32, htole32(host32));
+    EXPECT_EQ(host32, le32toh(htole32(host32)));
+    EXPECT_EQ(be32, htobe32(host32));
+    EXPECT_EQ(host32, be32toh(htobe32(host32)));
+
+    EXPECT_EQ(le64, htole64(host64));
+    EXPECT_EQ(host64, le64toh(htole64(host64)));
+    EXPECT_EQ(be64, htobe64(host64));
+    EXPECT_EQ(host64, be64toh(htobe64(host64)));
+}