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/*
* Copyright (C) 2010 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 "libcore_io_Memory.h"
#include <stdlib.h>
#include <string.h>
#include "jni/jni_internal.h"
#include "native_util.h"
#include "nativehelper/jni_macros.h"
#include "nativehelper/scoped_primitive_array.h"
#include "scoped_fast_native_object_access-inl.h"
namespace art {
// Use packed structures for access to unaligned data on targets with alignment restrictions.
// The compiler will generate appropriate code to access these structures without
// generating alignment exceptions.
template <typename T>
static inline T get_unaligned(const T* address) {
struct unaligned {
T v;
} __attribute__((packed));
const unaligned* p = reinterpret_cast<const unaligned*>(address);
return p->v;
}
template <typename T>
static inline void put_unaligned(T* address, T v) {
struct unaligned {
T v;
} __attribute__((packed));
unaligned* p = reinterpret_cast<unaligned*>(address);
p->v = v;
}
template <typename T>
static T cast(jlong address) {
return reinterpret_cast<T>(static_cast<uintptr_t>(address));
}
// Byte-swap 2 jshort values packed in a jint.
static inline jint bswap_2x16(jint v) {
// v is initially ABCD
v = __builtin_bswap32(v); // v=DCBA
v = (v << 16) | ((v >> 16) & 0xffff); // v=BADC
return v;
}
static inline void swapShorts(jshort* dstShorts, const jshort* srcShorts, size_t count) {
// Do 32-bit swaps as long as possible...
jint* dst = reinterpret_cast<jint*>(dstShorts);
const jint* src = reinterpret_cast<const jint*>(srcShorts);
for (size_t i = 0; i < count / 2; ++i) {
jint v = get_unaligned<jint>(src++);
put_unaligned<jint>(dst++, bswap_2x16(v));
}
if ((count % 2) != 0) {
jshort v = get_unaligned<jshort>(reinterpret_cast<const jshort*>(src));
put_unaligned<jshort>(reinterpret_cast<jshort*>(dst), __builtin_bswap16(v));
}
}
static inline void swapInts(jint* dstInts, const jint* srcInts, size_t count) {
for (size_t i = 0; i < count; ++i) {
jint v = get_unaligned<int>(srcInts++);
put_unaligned<jint>(dstInts++, __builtin_bswap32(v));
}
}
static inline void swapLongs(jlong* dstLongs, const jlong* srcLongs, size_t count) {
jint* dst = reinterpret_cast<jint*>(dstLongs);
const jint* src = reinterpret_cast<const jint*>(srcLongs);
for (size_t i = 0; i < count; ++i) {
jint v1 = get_unaligned<jint>(src++);
jint v2 = get_unaligned<jint>(src++);
put_unaligned<jint>(dst++, __builtin_bswap32(v2));
put_unaligned<jint>(dst++, __builtin_bswap32(v1));
}
}
static void Memory_peekByteArray(
JNIEnv* env, jclass, jlong srcAddress, jbyteArray dst, jint dstOffset, jint byteCount) {
env->SetByteArrayRegion(dst, dstOffset, byteCount, cast<const jbyte*>(srcAddress));
}
// Implements the peekXArray methods:
// - For unswapped access, we just use the JNI SetXArrayRegion functions.
// - For swapped access, we use GetXArrayElements and our own copy-and-swap routines.
// GetXArrayElements is disproportionately cheap on Dalvik because it doesn't copy (as opposed
// to Hotspot, which always copies). The SWAP_FN copies and swaps in one pass, which is cheaper
// than copying and then swapping in a second pass. Depending on future VM/GC changes, the
// swapped case might need to be revisited.
#define PEEKER(SCALAR_TYPE, JNI_NAME, SWAP_TYPE, SWAP_FN) \
{ \
if (swap) { \
Scoped##JNI_NAME##ArrayRW elements(env, dst); \
if (elements.get() == NULL) { \
return; \
} \
const SWAP_TYPE* src = cast<const SWAP_TYPE*>(srcAddress); \
SWAP_FN(reinterpret_cast<SWAP_TYPE*>(elements.get()) + dstOffset, src, count); /*NOLINT*/ \
} else { \
const SCALAR_TYPE* src = cast<const SCALAR_TYPE*>(srcAddress); \
env->Set##JNI_NAME##ArrayRegion(dst, dstOffset, count, src); \
} \
}
static void Memory_peekCharArray(JNIEnv* env,
jclass,
jlong srcAddress,
jcharArray dst,
jint dstOffset,
jint count,
jboolean swap) {
PEEKER(jchar, Char, jshort, swapShorts);
}
static void Memory_peekDoubleArray(JNIEnv* env,
jclass,
jlong srcAddress,
jdoubleArray dst,
jint dstOffset,
jint count,
jboolean swap) {
PEEKER(jdouble, Double, jlong, swapLongs);
}
static void Memory_peekFloatArray(JNIEnv* env,
jclass,
jlong srcAddress,
jfloatArray dst,
jint dstOffset,
jint count,
jboolean swap) {
PEEKER(jfloat, Float, jint, swapInts);
}
static void Memory_peekIntArray(JNIEnv* env,
jclass,
jlong srcAddress,
jintArray dst,
jint dstOffset,
jint count,
jboolean swap) {
PEEKER(jint, Int, jint, swapInts);
}
static void Memory_peekLongArray(JNIEnv* env,
jclass,
jlong srcAddress,
jlongArray dst,
jint dstOffset,
jint count,
jboolean swap) {
PEEKER(jlong, Long, jlong, swapLongs);
}
static void Memory_peekShortArray(JNIEnv* env,
jclass,
jlong srcAddress,
jshortArray dst,
jint dstOffset,
jint count,
jboolean swap) {
PEEKER(jshort, Short, jshort, swapShorts);
}
// The remaining Memory methods are contained in libcore/luni/src/main/native/libcore_io_Memory.cpp
static JNINativeMethod gMethods[] = {
FAST_NATIVE_METHOD(Memory, peekByteArray, "(J[BII)V"),
FAST_NATIVE_METHOD(Memory, peekCharArray, "(J[CIIZ)V"),
FAST_NATIVE_METHOD(Memory, peekDoubleArray, "(J[DIIZ)V"),
FAST_NATIVE_METHOD(Memory, peekFloatArray, "(J[FIIZ)V"),
FAST_NATIVE_METHOD(Memory, peekIntArray, "(J[IIIZ)V"),
FAST_NATIVE_METHOD(Memory, peekLongArray, "(J[JIIZ)V"),
FAST_NATIVE_METHOD(Memory, peekShortArray, "(J[SIIZ)V"),
};
void register_libcore_io_Memory(JNIEnv* env) { REGISTER_NATIVE_METHODS("libcore/io/Memory"); }
} // namespace art
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