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      1 /*
      2  * Copyright (C) 2010 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 A_BIT_READER_H_
     18 
     19 #define A_BIT_READER_H_
     20 
     21 #include <media/stagefright/foundation/ABase.h>
     22 
     23 #include <sys/types.h>
     24 #include <stdint.h>
     25 
     26 namespace android {
     27 
     28 struct ABitReader {
     29     ABitReader(const uint8_t *data, size_t size);
     30 
     31     uint32_t getBits(size_t n);
     32     void skipBits(size_t n);
     33 
     34     size_t numBitsLeft() const;
     35 
     36     const uint8_t *data() const;
     37 
     38 private:
     39     const uint8_t *mData;
     40     size_t mSize;
     41 
     42     uint32_t mReservoir;  // left-aligned bits
     43     size_t mNumBitsLeft;
     44 
     45     void fillReservoir();
     46     void putBits(uint32_t x, size_t n);
     47 
     48     DISALLOW_EVIL_CONSTRUCTORS(ABitReader);
     49 };
     50 
     51 }  // namespace android
     52 
     53 #endif  // A_BIT_READER_H_
     54