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/*
* 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.
*/
#include "jni_internal.h"
#include "object.h"
#include "JniConstants.h" // Last to avoid problems with LOG redefinition.
#ifdef HAVE__MEMCMP16
// "count" is in 16-bit units.
extern "C" uint32_t __memcmp16(const uint16_t* s0, const uint16_t* s1, size_t count);
#define MemCmp16 __memcmp16
#else
uint32_t MemCmp16(const uint16_t* s0, const uint16_t* s1, size_t count) {
for (size_t i = 0; i < count; i++) {
if (s0[i] != s1[i]) {
return static_cast<int32_t>(s0[i]) - static_cast<int32_t>(s1[i]);
}
}
return 0;
}
#endif
namespace art {
namespace {
jint String_compareTo(JNIEnv* env, jobject javaThis, jobject javaRhs) {
ScopedThreadStateChange tsc(Thread::Current(), Thread::kRunnable);
String* lhs = Decode<String*>(env, javaThis);
String* rhs = Decode<String*>(env, javaRhs);
if (rhs == NULL) {
Thread::Current()->ThrowNewException("Ljava/lang/NullPointerException;", "rhs == null");
return -1;
}
// Quick test for comparison of a string with itself.
if (lhs == rhs) {
return 0;
}
// TODO: is this still true?
// The annoying part here is that 0x00e9 - 0xffff != 0x00ea,
// because the interpreter converts the characters to 32-bit integers
// *without* sign extension before it subtracts them (which makes some
// sense since "char" is unsigned). So what we get is the result of
// 0x000000e9 - 0x0000ffff, which is 0xffff00ea.
int lhsCount = lhs->GetLength();
int rhsCount = rhs->GetLength();
int countDiff = lhsCount - rhsCount;
int minCount = (countDiff < 0) ? lhsCount : rhsCount;
const uint16_t* lhsChars = lhs->GetCharArray()->GetData() + lhs->GetOffset();
const uint16_t* rhsChars = rhs->GetCharArray()->GetData() + rhs->GetOffset();
int otherRes = MemCmp16(lhsChars, rhsChars, minCount);
if (otherRes != 0) {
return otherRes;
}
return countDiff;
}
jboolean String_equals(JNIEnv* env, jobject javaThis, jobject javaRhs) {
String* lhs = Decode<String*>(env, javaThis);
String* rhs = Decode<String*>(env, javaRhs);
// Quick test for comparison of a string with itself.
if (lhs == rhs) {
return JNI_TRUE;
}
// if (!(rhs instanceof String)) return false.
if (rhs == NULL || lhs->GetClass() != rhs->GetClass()) {
return JNI_FALSE;
}
// Quick length check.
int lhsCount = lhs->GetLength();
int rhsCount = rhs->GetLength();
if (lhsCount != rhsCount) {
return JNI_FALSE;
}
// You may, at this point, be tempted to pull out the hashCode fields
// and compare them. If both fields have been initialized, and they
// are not equal, we can return false immediately.
//
// However, the hashCode field is often not set. If it is set,
// there's an excellent chance that the String is being used as a key
// in a hashed data structure (e.g. HashMap). That data structure has
// already made the comparison and determined that the hashes are equal,
// making a check here redundant.
//
// It's not clear that checking the hashes will be a win in "typical"
// use cases. We err on the side of simplicity and ignore them.
const uint16_t* lhsChars = lhs->GetCharArray()->GetData() + lhs->GetOffset();
const uint16_t* rhsChars = rhs->GetCharArray()->GetData() + rhs->GetOffset();
return (MemCmp16(lhsChars, rhsChars, lhsCount) == 0) ? JNI_TRUE : JNI_FALSE;
}
/*
* public int indexOf(int c, int start)
*
* Scan forward through the string for a matching character.
* The character must be <= 0xffff; this method does not handle supplementary
* characters.
*
* Determine the index of the first character matching "ch". The string
* to search is described by "chars", "offset", and "count".
*
* The character must be <= 0xffff. Supplementary characters are handled in
* Java.
*
* The "start" parameter must be clamped to [0..count].
*
* Returns -1 if no match is found.
*/
jint String_fastIndexOf(JNIEnv* env, jobject javaThis, jint ch, jint start) {
String* s = Decode<String*>(env, javaThis);
const uint16_t* chars = s->GetCharArray()->GetData() + s->GetOffset();
if (start < 0) {
start = 0;
}
/* 16-bit loop, slightly better on ARM */
const uint16_t* ptr = chars + start;
const uint16_t* endPtr = chars + s->GetLength();
while (ptr < endPtr) {
if (*ptr++ == ch) {
return (ptr-1) - chars;
}
}
return -1;
}
jstring String_intern(JNIEnv* env, jobject javaThis) {
String* s = Decode<String*>(env, javaThis);
String* result = s->Intern();
return AddLocalReference<jstring>(env, result);
}
JNINativeMethod gMethods[] = {
NATIVE_METHOD(String, compareTo, "(Ljava/lang/String;)I"),
NATIVE_METHOD(String, equals, "(Ljava/lang/Object;)Z"),
NATIVE_METHOD(String, fastIndexOf, "(II)I"),
NATIVE_METHOD(String, intern, "()Ljava/lang/String;"),
};
} // namespace
void register_java_lang_String(JNIEnv* env) {
jniRegisterNativeMethods(env, "java/lang/String", gMethods, NELEM(gMethods));
}
} // namespace art
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