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// Copyright 2016 The Draco Authors.
//
// 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.
//
// File provides direct encoding of bits with arithmetic encoder interface.
#ifndef DRACO_COMPRESSION_BIT_CODERS_FOLDED_INTEGER_BIT_DECODER_H_
#define DRACO_COMPRESSION_BIT_CODERS_FOLDED_INTEGER_BIT_DECODER_H_
#include <vector>
#include "draco/core/decoder_buffer.h"
namespace draco {
// See FoldedBit32Encoder for more details.
template <class BitDecoderT>
class FoldedBit32Decoder {
public:
FoldedBit32Decoder() {}
~FoldedBit32Decoder() {}
// Sets |source_buffer| as the buffer to decode bits from.
bool StartDecoding(DecoderBuffer *source_buffer) {
for (int i = 0; i < 32; i++) {
if (!folded_number_decoders_[i].StartDecoding(source_buffer))
return false;
}
return bit_decoder_.StartDecoding(source_buffer);
}
// Decode one bit. Returns true if the bit is a 1, otherwise false.
bool DecodeNextBit() { return bit_decoder_.DecodeNextBit(); }
// Decode the next |nbits| and return the sequence in |value|. |nbits| must be
// > 0 and <= 32.
void DecodeLeastSignificantBits32(int nbits, uint32_t *value) {
uint32_t result = 0;
for (int i = 0; i < nbits; ++i) {
const bool bit = folded_number_decoders_[i].DecodeNextBit();
result = (result << 1) + bit;
}
*value = result;
}
void EndDecoding() {
for (int i = 0; i < 32; i++) {
folded_number_decoders_[i].EndDecoding();
}
bit_decoder_.EndDecoding();
}
private:
void Clear() {
for (int i = 0; i < 32; i++) {
folded_number_decoders_[i].Clear();
}
bit_decoder_.Clear();
}
std::array<BitDecoderT, 32> folded_number_decoders_;
BitDecoderT bit_decoder_;
};
} // namespace draco
#endif // DRACO_COMPRESSION_BIT_CODERS_FOLDED_INTEGER_BIT_DECODER_H_
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