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87 lines
2.6 KiB
C++
87 lines
2.6 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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// A set of classes for quantizing and dequantizing of floating point values
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// into integers.
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// The quantization works on all floating point numbers within (-range, +range)
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// interval producing integers in range
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// (-max_quantized_value, +max_quantized_value).
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#ifndef DRACO_CORE_QUANTIZATION_UTILS_H_
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#define DRACO_CORE_QUANTIZATION_UTILS_H_
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#include <cmath>
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#include <cstdint>
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#include "core/macros.h"
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namespace draco {
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// Class for quantizing single precision floating point values. The values must
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// be centered around zero and be within interval (-range, +range), where the
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// range is specified in the Init() method.
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class Quantizer {
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public:
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Quantizer();
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void Init(float range, int32_t max_quantized_value);
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inline int32_t QuantizeFloat(float val) const {
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const bool neg = (val < 0.f);
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if (neg) {
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val = -val;
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}
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val /= range_;
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const int32_t ret = static_cast<int32_t>(
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floor(val * static_cast<float>(max_quantized_value_) + 0.5f));
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if (neg)
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return -ret;
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return ret;
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}
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inline int32_t operator()(float val) const { return QuantizeFloat(val); }
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private:
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float range_;
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int32_t max_quantized_value_;
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};
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// Class for dequantizing values that were previously quantized using the
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// Quantizer class.
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class Dequantizer {
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public:
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Dequantizer();
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// Initializes the dequantizer. Both parameters must correspond to the values
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// provided to the initializer of the Quantizer class.
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void Init(float range, int32_t max_quantized_value);
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inline float DequantizeFloat(int32_t val) const {
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const bool neg = (val < 0);
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if (neg) {
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val = -val;
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}
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float norm_value = static_cast<float>(val) * max_quantized_value_factor_;
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if (neg)
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norm_value = -norm_value;
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return norm_value * range_;
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}
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inline float operator()(int32_t val) const { return DequantizeFloat(val); }
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private:
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float range_;
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// Distance between two normalized dequantized values.
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float max_quantized_value_factor_;
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};
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} // namespace draco
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#endif // DRACO_CORE_QUANTIZATION_UTILS_H_
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