79 lines
2.6 KiB
C++
79 lines
2.6 KiB
C++
/*
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* Copyright (C) 2010 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef AML_MP_BIT_READER_H_
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#define AML_MP_BIT_READER_H_
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//#include <media/stagefright/foundation/ABase.h>
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#include <sys/types.h>
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#include <stdint.h>
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namespace aml_mp {
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class AmlMpBitReader {
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public:
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AmlMpBitReader(const uint8_t *data, size_t size);
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virtual ~AmlMpBitReader();
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// Tries to get |n| bits. If not successful, returns |fallback|. Otherwise, returns result.
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// Reading 0 bits will always succeed and return 0.
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uint32_t getBitsWithFallback(size_t n, uint32_t fallback);
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// Tries to get |n| bits. If not successful, returns false. Otherwise, stores result in |out|
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// and returns true. Use !overRead() to determine if this call was successful. Reading 0 bits
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// will always succeed and write 0 in |out|.
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bool getBitsGraceful(size_t n, uint32_t *out);
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// Gets |n| bits and returns result. ABORTS if unsuccessful. Reading 0 bits will always
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// succeed.
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uint32_t getBits(size_t n);
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// Tries to skip |n| bits. Returns true iff successful. Skipping 0 bits will always succeed.
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bool skipBits(size_t n);
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// "Puts" |n| bits with the value |x| back virtually into the bit stream. The put-back bits
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// are not actually written into the data, but are tracked in a separate buffer that can
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// store at most 32 bits. This is a no-op if the stream has already been over-read.
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void putBits(uint32_t x, size_t n);
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size_t numBitsLeft() const;
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const uint8_t *data() const;
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// Returns true iff the stream was over-read (e.g. any getBits operation has been unsuccessful
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// due to overread (and not trying to read >32 bits).)
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bool overRead() const { return mOverRead; }
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protected:
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const uint8_t *mData;
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size_t mSize;
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uint32_t mReservoir; // left-aligned bits
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size_t mNumBitsLeft;
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bool mOverRead;
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virtual bool fillReservoir();
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AmlMpBitReader(const AmlMpBitReader&) = delete;
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AmlMpBitReader& operator= (const AmlMpBitReader&) = delete;
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};
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} // namespace android
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#endif // A_BIT_READER_H_
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