/*
* Copyright (C) 2008 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.
*/
/*
* java.lang.Class native methods
*/
#include "Dalvik.h"
#include "native/InternalNativePriv.h"
/*
* The VM makes guarantees about the atomicity of accesses to primitive
* variables. These guarantees also apply to elements of arrays.
* In particular, 8-bit, 16-bit, and 32-bit accesses must be atomic and
* must not cause "word tearing". Accesses to 64-bit array elements must
* either be atomic or treated as two 32-bit operations. References are
* always read and written atomically, regardless of the number of bits
* used to represent them.
*
* We can't rely on standard libc functions like memcpy() and memmove()
* in our implementation of System.arraycopy(), because they may copy
* byte-by-byte (either for the full run or for "unaligned" parts at the
* start or end). We need to use functions that guarantee 16-bit or 32-bit
* atomicity as appropriate.
*
* System.arraycopy() is heavily used, so having an efficient implementation
* is important. The bionic libc provides a platform-optimized memory move
* function that should be used when possible. If it's not available,
* the trivial "reference implementation" versions below can be used until
* a proper version can be written.
*
* For these functions, The caller must guarantee that dest/src are aligned
* appropriately for the element type, and that n is a multiple of the
* element size.
*/
#ifdef __BIONIC__
/* always present in bionic libc */
#define HAVE_MEMMOVE_WORDS
#endif
#ifdef HAVE_MEMMOVE_WORDS
extern "C" void _memmove_words(void* dest, const void* src, size_t n);
#define move16 _memmove_words
#define move32 _memmove_words
#else
static void move16(void* dest, const void* src, size_t n)
{
assert((((uintptr_t) dest | (uintptr_t) src | n) & 0x01) == 0);
uint16_t* d = (uint16_t*) dest;
const uint16_t* s = (uint16_t*) src;
n /= sizeof(uint16_t);
if (d < s) {
/* copy forward */
while (n--) {
*d++ = *s++;
}
} else {
/* copy backward */
d += n;
s += n;
while (n--) {
*--d = *--s;
}
}
}
static void move32(void* dest, const void* src, size_t n)
{
assert((((uintptr_t) dest | (uintptr_t) src | n) & 0x03) == 0);
uint32_t* d = (uint32_t*) dest;
const uint32_t* s = (uint32_t*) src;
n /= sizeof(uint32_t);
if (d < s) {
/* copy forward */
while (n--) {
*d++ = *s++;
}
} else {
/* copy backward */
d += n;
s += n;
while (n--) {
*--d = *--s;
}
}
}
#endif /*HAVE_MEMMOVE_WORDS*/
/*
* public static void arraycopy(Object src, int srcPos, Object dest,
* int destPos, int length)
*
* The description of this function is long, and describes a multitude
* of checks and exceptions.
*/
static void Dalvik_java_lang_System_arraycopy(const u4* args, JValue* pResult)
{
ArrayObject* srcArray = (ArrayObject*) args[0];
int srcPos = args[1];
ArrayObject* dstArray = (ArrayObject*) args[2];
int dstPos = args[3];
int length = args[4];
/* Check for null pointers. */
if (srcArray == NULL) {
dvmThrowNullPointerException("src == null");
RETURN_VOID();
}
if (dstArray == NULL) {
dvmThrowNullPointerException("dst == null");
RETURN_VOID();
}
/* Make sure source and destination are arrays. */
if (!dvmIsArray(srcArray)) {
dvmThrowArrayStoreExceptionNotArray(((Object*)srcArray)->clazz, "source");
RETURN_VOID();
}
if (!dvmIsArray(dstArray)) {
dvmThrowArrayStoreExceptionNotArray(((Object*)dstArray)->clazz, "destination");
RETURN_VOID();
}
/* avoid int overflow */
if (srcPos < 0 || dstPos < 0 || length < 0 ||
srcPos > (int) srcArray->length - length ||
dstPos > (int) dstArray->length - length)
{
dvmThrowExceptionFmt(gDvm.exArrayIndexOutOfBoundsException,
"src.length=%d srcPos=%d dst.length=%d dstPos=%d length=%d",
srcArray->length, srcPos, dstArray->length, dstPos, length);
RETURN_VOID();
}
ClassObject* srcClass = srcArray->clazz;
ClassObject* dstClass = dstArray->clazz;
char srcType = srcClass->descriptor[1];
char dstType = dstClass->descriptor[1];
/*
* If one of the arrays holds a primitive type, the other array must
* hold the same type.
*/
bool srcPrim = (srcType != '[' && srcType != 'L');
bool dstPrim = (dstType != '[' && dstType != 'L');
if (srcPrim || dstPrim) {
if (srcPrim != dstPrim || srcType != dstType) {
dvmThrowArrayStoreExceptionIncompatibleArrays(srcClass, dstClass);
RETURN_VOID();
}
if (false) ALOGD("arraycopy prim[%c] dst=%p %d src=%p %d len=%d",
srcType, dstArray->contents, dstPos,
srcArray->contents, srcPos, length);
switch (srcType) {
case 'B':
case 'Z':
/* 1 byte per element */
memmove((u1*) dstArray->contents + dstPos,
(const u1*) srcArray->contents + srcPos,
length);
break;
case 'C':
case 'S':
/* 2 bytes per element */
move16((u1*) dstArray->contents + dstPos * 2,
(const u1*) srcArray->contents + srcPos * 2,
length * 2);
break;
case 'F':
case 'I':
/* 4 bytes per element */
move32((u1*) dstArray->contents + dstPos * 4,
(const u1*) srcArray->contents + srcPos * 4,
length * 4);
break;
case 'D':
case 'J':
/*
* 8 bytes per element. We don't need to guarantee atomicity
* of the entire 64-bit word, so we can use the 32-bit copier.
*/
move32((u1*) dstArray->contents + dstPos * 8,
(const u1*) srcArray->contents + srcPos * 8,
length * 8);
break;
default: /* illegal array type */
ALOGE("Weird array type '%s'", srcClass->descriptor);
dvmAbort();
}
} else {
/*
* Neither class is primitive. See if elements in "src" are instances
* of elements in "dst" (e.g. copy String to String or String to
* Object).
*/
const int width = sizeof(Object*);
if (srcClass->arrayDim == dstClass->arrayDim &&
dvmInstanceof(srcClass, dstClass))
{
/*
* "dst" can hold "src"; copy the whole thing.
*/
if (false) ALOGD("arraycopy ref dst=%p %d src=%p %d len=%d",
dstArray->contents, dstPos * width,
srcArray->contents, srcPos * width,
length * width);
move32((u1*)dstArray->contents + dstPos * width,
(const u1*)srcArray->contents + srcPos * width,
length * width);
dvmWriteBarrierArray(dstArray, dstPos, dstPos+length);
} else {
/*
* The arrays are not fundamentally compatible. However, we
* may still be able to do this if the destination object is
* compatible (e.g. copy Object[] to String[], but the Object
* being copied is actually a String). We need to copy elements
* one by one until something goes wrong.
*
* Because of overlapping moves, what we really want to do
* is compare the types and count up how many we can move,
* then call move32() to shift the actual data. If we just
* start from the front we could do a smear rather than a move.
*/
Object** srcObj;
int copyCount;
ClassObject* clazz = NULL;
srcObj = ((Object**)(void*)srcArray->contents) + srcPos;
if (length > 0 && srcObj[0] != NULL)
{
clazz = srcObj[0]->clazz;
if (!dvmCanPutArrayElement(clazz, dstClass))
clazz = NULL;
}
for (copyCount = 0; copyCount < length; copyCount++)
{
if (srcObj[copyCount] != NULL &&
srcObj[copyCount]->clazz != clazz &&
!dvmCanPutArrayElement(srcObj[copyCount]->clazz, dstClass))
{
/* can't put this element into the array */
break;
}
}
if (false) ALOGD("arraycopy iref dst=%p %d src=%p %d count=%d of %d",
dstArray->contents, dstPos * width,
srcArray->contents, srcPos * width,
copyCount, length);
move32((u1*)dstArray->contents + dstPos * width,
(const u1*)srcArray->contents + srcPos * width,
copyCount * width);
dvmWriteBarrierArray(dstArray, 0, copyCount);
if (copyCount != length) {
dvmThrowArrayStoreExceptionIncompatibleArrayElement(srcPos + copyCount,
srcObj[copyCount]->clazz, dstClass);
RETURN_VOID();
}
}
}
RETURN_VOID();
}
/*
* static long currentTimeMillis()
*
* Current time, in miliseconds. This doesn't need to be internal to the
* VM, but we're already handling java.lang.System here.
*/
static void Dalvik_java_lang_System_currentTimeMillis(const u4* args,
JValue* pResult)
{
struct timeval tv;
UNUSED_PARAMETER(args);
gettimeofday(&tv, (struct timezone *) NULL);
long long when = tv.tv_sec * 1000LL + tv.tv_usec / 1000;
RETURN_LONG(when);
}
/*
* static long nanoTime()
*
* Current monotonically-increasing time, in nanoseconds. This doesn't
* need to be internal to the VM, but we're already handling
* java.lang.System here.
*/
static void Dalvik_java_lang_System_nanoTime(const u4* args, JValue* pResult)
{
UNUSED_PARAMETER(args);
u8 when = dvmGetRelativeTimeNsec();
RETURN_LONG(when);
}
/*
* static int identityHashCode(Object x)
*
* Returns that hash code that the default hashCode()
* method would return for "x", even if "x"s class
* overrides hashCode().
*/
static void Dalvik_java_lang_System_identityHashCode(const u4* args,
JValue* pResult)
{
Object* thisPtr = (Object*) args[0];
RETURN_INT(dvmIdentityHashCode(thisPtr));
}
static void Dalvik_java_lang_System_mapLibraryName(const u4* args,
JValue* pResult)
{
StringObject* nameObj = (StringObject*) args[0];
StringObject* result = NULL;
char* name;
char* mappedName;
if (nameObj == NULL) {
dvmThrowNullPointerException("userLibName == null");
RETURN_VOID();
}
name = dvmCreateCstrFromString(nameObj);
mappedName = dvmCreateSystemLibraryName(name);
if (mappedName != NULL) {
result = dvmCreateStringFromCstr(mappedName);
dvmReleaseTrackedAlloc((Object*) result, NULL);
}
free(name);
free(mappedName);
RETURN_PTR(result);
}
const DalvikNativeMethod dvm_java_lang_System[] = {
{ "arraycopy", "(Ljava/lang/Object;ILjava/lang/Object;II)V",
Dalvik_java_lang_System_arraycopy },
{ "currentTimeMillis", "()J",
Dalvik_java_lang_System_currentTimeMillis },
{ "identityHashCode", "(Ljava/lang/Object;)I",
Dalvik_java_lang_System_identityHashCode },
{ "mapLibraryName", "(Ljava/lang/String;)Ljava/lang/String;",
Dalvik_java_lang_System_mapLibraryName },
{ "nanoTime", "()J",
Dalvik_java_lang_System_nanoTime },
{ NULL, NULL, NULL },
};