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https://git.mirrors.martin98.com/https://github.com/google/draco
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73bb3c8530
- Improved compression for triangular meshes (~10%) - Added WebAssembly decoder - Code cleanup + robustness fixes
68 lines
2.0 KiB
C++
68 lines
2.0 KiB
C++
// Copyright 2016 The Draco Authors.
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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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#include "core/adaptive_rans_bit_decoder.h"
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#include "core/adaptive_rans_bit_coding_shared.h"
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namespace draco {
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AdaptiveRAnsBitDecoder::AdaptiveRAnsBitDecoder() : p0_f_(0.5) {}
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AdaptiveRAnsBitDecoder::~AdaptiveRAnsBitDecoder() { Clear(); }
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bool AdaptiveRAnsBitDecoder::StartDecoding(DecoderBuffer *source_buffer) {
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Clear();
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uint32_t size_in_bytes;
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if (!source_buffer->Decode(&size_in_bytes))
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return false;
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if (size_in_bytes > source_buffer->remaining_size())
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return false;
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if (ans_read_init(&ans_decoder_,
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reinterpret_cast<uint8_t *>(
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const_cast<char *>(source_buffer->data_head())),
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size_in_bytes) != 0)
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return false;
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source_buffer->Advance(size_in_bytes);
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return true;
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}
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bool AdaptiveRAnsBitDecoder::DecodeNextBit() {
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const uint8_t p0 = clamp_probability(p0_f_);
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const bool bit = static_cast<bool>(rabs_read(&ans_decoder_, p0));
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p0_f_ = update_probability(p0_f_, bit);
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return bit;
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}
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void AdaptiveRAnsBitDecoder::DecodeLeastSignificantBits32(int nbits,
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uint32_t *value) {
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DCHECK_EQ(true, nbits <= 32);
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DCHECK_EQ(true, nbits > 0);
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uint32_t result = 0;
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while (nbits) {
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result = (result << 1) + DecodeNextBit();
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--nbits;
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}
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*value = result;
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}
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void AdaptiveRAnsBitDecoder::Clear() {
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ans_read_end(&ans_decoder_);
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p0_f_ = 0.5;
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}
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} // namespace draco
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