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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef ART_RUNTIME_STACK_INDIRECT_REFERENCE_TABLE_H_
     18 #define ART_RUNTIME_STACK_INDIRECT_REFERENCE_TABLE_H_
     19 
     20 #include "base/logging.h"
     21 #include "base/macros.h"
     22 
     23 namespace art {
     24 namespace mirror {
     25 class Object;
     26 }
     27 class Thread;
     28 
     29 // Stack allocated indirect reference table. It can allocated within
     30 // the bridge frame between managed and native code backed by stack
     31 // storage or manually allocated by SirtRef to hold one reference.
     32 class StackIndirectReferenceTable {
     33  public:
     34   explicit StackIndirectReferenceTable(mirror::Object* object) :
     35       number_of_references_(1), link_(NULL) {
     36     references_[0] = object;
     37   }
     38 
     39   ~StackIndirectReferenceTable() {}
     40 
     41   // Number of references contained within this SIRT
     42   size_t NumberOfReferences() const {
     43     return number_of_references_;
     44   }
     45 
     46   // Link to previous SIRT or NULL
     47   StackIndirectReferenceTable* GetLink() const {
     48     return link_;
     49   }
     50 
     51   void SetLink(StackIndirectReferenceTable* sirt) {
     52     DCHECK_NE(this, sirt);
     53     link_ = sirt;
     54   }
     55 
     56   mirror::Object* GetReference(size_t i) const {
     57     DCHECK_LT(i, number_of_references_);
     58     return references_[i];
     59   }
     60 
     61   void SetReference(size_t i, mirror::Object* object) {
     62     DCHECK_LT(i, number_of_references_);
     63     references_[i] = object;
     64   }
     65 
     66   bool Contains(mirror::Object** sirt_entry) const {
     67     // A SIRT should always contain something. One created by the
     68     // jni_compiler should have a jobject/jclass as a native method is
     69     // passed in a this pointer or a class
     70     DCHECK_GT(number_of_references_, 0U);
     71     return ((&references_[0] <= sirt_entry)
     72             && (sirt_entry <= (&references_[number_of_references_ - 1])));
     73   }
     74 
     75   // Offset of length within SIRT, used by generated code
     76   static size_t NumberOfReferencesOffset() {
     77     return OFFSETOF_MEMBER(StackIndirectReferenceTable, number_of_references_);
     78   }
     79 
     80   // Offset of link within SIRT, used by generated code
     81   static size_t LinkOffset() {
     82     return OFFSETOF_MEMBER(StackIndirectReferenceTable, link_);
     83   }
     84 
     85  private:
     86   StackIndirectReferenceTable() {}
     87 
     88   size_t number_of_references_;
     89   StackIndirectReferenceTable* link_;
     90 
     91   // number_of_references_ are available if this is allocated and filled in by jni_compiler.
     92   mirror::Object* references_[1];
     93 
     94   DISALLOW_COPY_AND_ASSIGN(StackIndirectReferenceTable);
     95 };
     96 
     97 }  // namespace art
     98 
     99 #endif  // ART_RUNTIME_STACK_INDIRECT_REFERENCE_TABLE_H_
    100