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      1 /*
      2  * Copyright (C) 2009 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 
     18 #ifndef GRALLOC_ALLOCATOR_H_
     19 #define GRALLOC_ALLOCATOR_H_
     20 
     21 #include <stdint.h>
     22 #include <sys/types.h>
     23 
     24 #include "gr.h"
     25 
     26 // ----------------------------------------------------------------------------
     27 
     28 /*
     29  * A simple templatized doubly linked-list implementation
     30  */
     31 
     32 template <typename NODE>
     33 class LinkedList
     34 {
     35     NODE*  mFirst;
     36     NODE*  mLast;
     37 
     38 public:
     39                 LinkedList() : mFirst(0), mLast(0) { }
     40     bool        isEmpty() const { return mFirst == 0; }
     41     NODE const* head() const { return mFirst; }
     42     NODE*       head() { return mFirst; }
     43     NODE const* tail() const { return mLast; }
     44     NODE*       tail() { return mLast; }
     45 
     46     void insertAfter(NODE* node, NODE* newNode) {
     47         newNode->prev = node;
     48         newNode->next = node->next;
     49         if (node->next == 0) mLast = newNode;
     50         else                 node->next->prev = newNode;
     51         node->next = newNode;
     52     }
     53 
     54     void insertBefore(NODE* node, NODE* newNode) {
     55          newNode->prev = node->prev;
     56          newNode->next = node;
     57          if (node->prev == 0)   mFirst = newNode;
     58          else                   node->prev->next = newNode;
     59          node->prev = newNode;
     60     }
     61 
     62     void insertHead(NODE* newNode) {
     63         if (mFirst == 0) {
     64             mFirst = mLast = newNode;
     65             newNode->prev = newNode->next = 0;
     66         } else {
     67             newNode->prev = 0;
     68             newNode->next = mFirst;
     69             mFirst->prev = newNode;
     70             mFirst = newNode;
     71         }
     72     }
     73 
     74     void insertTail(NODE* newNode) {
     75         if (mLast == 0) {
     76             insertHead(newNode);
     77         } else {
     78             newNode->prev = mLast;
     79             newNode->next = 0;
     80             mLast->next = newNode;
     81             mLast = newNode;
     82         }
     83     }
     84 
     85     NODE* remove(NODE* node) {
     86         if (node->prev == 0)    mFirst = node->next;
     87         else                    node->prev->next = node->next;
     88         if (node->next == 0)    mLast = node->prev;
     89         else                    node->next->prev = node->prev;
     90         return node;
     91     }
     92 };
     93 
     94 class SimpleBestFitAllocator
     95 {
     96 public:
     97 
     98     SimpleBestFitAllocator();
     99     SimpleBestFitAllocator(size_t size);
    100     ~SimpleBestFitAllocator();
    101 
    102     ssize_t     setSize(size_t size);
    103 
    104     ssize_t     allocate(size_t size, uint32_t flags = 0);
    105     ssize_t     deallocate(size_t offset);
    106     size_t      size() const;
    107 
    108 private:
    109     struct chunk_t {
    110         chunk_t(size_t start, size_t size)
    111             : start(start), size(size), free(1), prev(0), next(0) {
    112         }
    113         size_t              start;
    114         size_t              size : 28;
    115         int                 free : 4;
    116         mutable chunk_t*    prev;
    117         mutable chunk_t*    next;
    118     };
    119 
    120     ssize_t  alloc(size_t size, uint32_t flags);
    121     chunk_t* dealloc(size_t start);
    122 
    123     static const int    kMemoryAlign;
    124     mutable Locker      mLock;
    125     LinkedList<chunk_t> mList;
    126     size_t              mHeapSize;
    127 };
    128 
    129 #endif /* GRALLOC_ALLOCATOR_H_ */
    130