83 lines
2.8 KiB
C++
83 lines
2.8 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 <stdint.h>
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#include <cmath>
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#include "draco/core/macros.h"
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namespace draco {
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// Class for quantizing single precision floating point values. The values
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// should be centered around zero and be within interval (-range, +range), where
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// the range is specified in the Init() method. Alternatively, the quantization
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// can be defined by |delta| that specifies the distance between two quantized
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// values. Note that the quantizer always snaps the values to the nearest
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// integer value. E.g. for |delta| == 1.f, values -0.4f and 0.4f would be
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// both quantized to 0 while value 0.6f would be quantized to 1. If a value
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// lies exactly between two quantized states, it is always rounded up. E.g.,
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// for |delta| == 1.f, value -0.5f would be quantized to 0 while 0.5f would be
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// quantized to 1.
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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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void Init(float delta);
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inline int32_t QuantizeFloat(float val) const {
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val *= inverse_delta_;
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return static_cast<int32_t>(floor(val + 0.5f));
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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 inverse_delta_;
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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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// Returns false when the initialization fails.
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bool Init(float range, int32_t max_quantized_value);
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// Initializes the dequantizer using the |delta| between two quantized values.
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bool Init(float delta);
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inline float DequantizeFloat(int32_t val) const {
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return static_cast<float>(val) * delta_;
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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 delta_;
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};
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} // namespace draco
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#endif // DRACO_CORE_QUANTIZATION_UTILS_H_
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