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juce_LookupTable.h
1/*
2 ==============================================================================
3
4 This file is part of the JUCE library.
5 Copyright (c) 2017 - ROLI Ltd.
6
7 JUCE is an open source library subject to commercial or open-source
8 licensing.
9
10 By using JUCE, you agree to the terms of both the JUCE 5 End-User License
11 Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
12 27th April 2017).
13
14 End User License Agreement: www.juce.com/juce-5-licence
15 Privacy Policy: www.juce.com/juce-5-privacy-policy
16
17 Or: You may also use this code under the terms of the GPL v3 (see
18 www.gnu.org/licenses).
19
20 JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
21 EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
22 DISCLAIMED.
23
24 ==============================================================================
25*/
26
27 namespace juce
28{
29 namespace dsp
30{
31
52 template <typename FloatType>
53 class LookupTable
54{
55 public:
63 LookupTable();
64
71 LookupTable (const std::function<FloatType(size_t)>& functionToApproximate, size_t numPointsToUse);
72
83 void initialise (const std::function<FloatType(size_t)>& functionToApproximate, size_t numPointsToUse);
84
85 //==============================================================================
96 FloatType getUnchecked (FloatType index) const noexcept
97 {
98 jassert (isInitialised()); // Use the non-default constructor or call initialise() before first use
99 jassert (isPositiveAndBelow (index, FloatType (getNumPoints())));
100
101 auto i = truncatePositiveToUnsignedInt (index);
102 auto f = index - FloatType (i);
103 jassert (isPositiveAndBelow (f, FloatType (1)));
104
105 auto x0 = data.getUnchecked (static_cast<int> (i));
106 auto x1 = data.getUnchecked (static_cast<int> (i + 1));
107
108 return jmap (f, x0, x1);
109 }
110
111 //==============================================================================
124 FloatType get (FloatType index) const noexcept
125 {
126 if (index >= getNumPoints())
127 index = static_cast<FloatType> (getGuardIndex());
128 else if (index < 0)
129 index = {};
130
131 return getUnchecked (index);
132 }
133
134 //==============================================================================
136 FloatType operator[] (FloatType index) const noexcept { return getUnchecked (index); }
137
139 size_t getNumPoints() const noexcept { return static_cast<size_t> (data.size()) - 1; }
140
142 bool isInitialised() const noexcept { return data.size() > 1; }
143
144 private:
145 //==============================================================================
146 Array<FloatType> data;
147
148 void prepare() noexcept;
149 static size_t getRequiredBufferSize (size_t numPointsToUse) noexcept { return numPointsToUse + 1; }
150 size_t getGuardIndex() const noexcept { return getRequiredBufferSize (getNumPoints()) - 1; }
151
152 JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (LookupTable)
153};
154
155
156//==============================================================================
174 template <typename FloatType>
175 class LookupTableTransform
176{
177 public:
178 //==============================================================================
186 LookupTableTransform() = default;
187
188 //==============================================================================
199 LookupTableTransform (const std::function<FloatType(FloatType)>& functionToApproximate,
200 FloatType minInputValueToUse,
201 FloatType maxInputValueToUse,
202 size_t numPoints)
203 {
204 initialise (functionToApproximate, minInputValueToUse, maxInputValueToUse, numPoints);
205 }
206
207 //==============================================================================
218 void initialise (const std::function<FloatType(FloatType)>& functionToApproximate,
219 FloatType minInputValueToUse,
220 FloatType maxInputValueToUse,
221 size_t numPoints);
222
223 //==============================================================================
234 FloatType processSampleUnchecked (FloatType value) const noexcept
235 {
236 jassert (value >= minInputValue && value <= maxInputValue);
237 return lookupTable[scaler * value + offset];
238 }
239
240 //==============================================================================
254 FloatType processSample (FloatType value) const noexcept
255 {
256 auto index = scaler * jlimit (minInputValue, maxInputValue, value) + offset;
257 jassert (isPositiveAndBelow (index, FloatType (lookupTable.getNumPoints())));
258
259 return lookupTable[index];
260 }
261
262 //==============================================================================
264 FloatType operator[] (FloatType index) const noexcept { return processSampleUnchecked (index); }
265
267 FloatType operator() (FloatType index) const noexcept { return processSample (index); }
268
269 //==============================================================================
273 void processUnchecked (const FloatType* input, FloatType* output, size_t numSamples) const noexcept
274 {
275 for (size_t i = 0; i < numSamples; ++i)
276 output[i] = processSampleUnchecked (input[i]);
277 }
278
279 //==============================================================================
283 void process (const FloatType* input, FloatType* output, size_t numSamples) const noexcept
284 {
285 for (size_t i = 0; i < numSamples; ++i)
286 output[i] = processSample (input[i]);
287 }
288
289 //==============================================================================
312 static double calculateMaxRelativeError (const std::function<FloatType(FloatType)>& functionToApproximate,
313 FloatType minInputValue,
314 FloatType maxInputValue,
315 size_t numPoints,
316 size_t numTestPoints = 0);
317 private:
318 //==============================================================================
319 static double calculateRelativeDifference (double, double) noexcept;
320
321 //==============================================================================
322 LookupTable<FloatType> lookupTable;
323
324 FloatType minInputValue, maxInputValue;
325 FloatType scaler, offset;
326
327 JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (LookupTableTransform)
328};
329
330} // namespace dsp
331} // namespace juce
juce::Array
Definition: juce_Array.h:56
juce::Array::getUnchecked
ElementType getUnchecked(int index) const
Definition: juce_Array.h:252
juce::Array::size
int size() const noexcept
Definition: juce_Array.h:215
juce::dsp::LookupTableTransform
Definition: juce_LookupTable.h:176
juce::dsp::LookupTableTransform::LookupTableTransform
LookupTableTransform(const std::function< FloatType(FloatType)> &functionToApproximate, FloatType minInputValueToUse, FloatType maxInputValueToUse, size_t numPoints)
Definition: juce_LookupTable.h:199
juce::dsp::LookupTableTransform::operator[]
FloatType operator[](FloatType index) const noexcept
Definition: juce_LookupTable.h:264
juce::dsp::LookupTableTransform::processSampleUnchecked
FloatType processSampleUnchecked(FloatType value) const noexcept
Definition: juce_LookupTable.h:234
juce::dsp::LookupTableTransform::initialise
void initialise(const std::function< FloatType(FloatType)> &functionToApproximate, FloatType minInputValueToUse, FloatType maxInputValueToUse, size_t numPoints)
Definition: juce_LookupTable.cpp:75
juce::dsp::LookupTableTransform::process
void process(const FloatType *input, FloatType *output, size_t numSamples) const noexcept
Definition: juce_LookupTable.h:283
juce::dsp::LookupTableTransform::processUnchecked
void processUnchecked(const FloatType *input, FloatType *output, size_t numSamples) const noexcept
Definition: juce_LookupTable.h:273
juce::dsp::LookupTableTransform::processSample
FloatType processSample(FloatType value) const noexcept
Definition: juce_LookupTable.h:254
juce::dsp::LookupTableTransform::operator()
FloatType operator()(FloatType index) const noexcept
Definition: juce_LookupTable.h:267
juce::dsp::LookupTableTransform::LookupTableTransform
LookupTableTransform()=default
juce::dsp::LookupTableTransform::calculateMaxRelativeError
static double calculateMaxRelativeError(const std::function< FloatType(FloatType)> &functionToApproximate, FloatType minInputValue, FloatType maxInputValue, size_t numPoints, size_t numTestPoints=0)
Definition: juce_LookupTable.cpp:101
juce::dsp::LookupTable
Definition: juce_LookupTable.h:54
juce::dsp::LookupTable::get
FloatType get(FloatType index) const noexcept
Definition: juce_LookupTable.h:124
juce::dsp::LookupTable::operator[]
FloatType operator[](FloatType index) const noexcept
Definition: juce_LookupTable.h:136
juce::dsp::LookupTable::getUnchecked
FloatType getUnchecked(FloatType index) const noexcept
Definition: juce_LookupTable.h:96
juce::dsp::LookupTable::isInitialised
bool isInitialised() const noexcept
Definition: juce_LookupTable.h:142
juce::dsp::LookupTable::getNumPoints
size_t getNumPoints() const noexcept
Definition: juce_LookupTable.h:139
juce::dsp::LookupTable::initialise
void initialise(const std::function< FloatType(size_t)> &functionToApproximate, size_t numPointsToUse)
Definition: juce_LookupTable.cpp:47
juce::dsp::LookupTable::LookupTable
LookupTable()
Definition: juce_LookupTable.cpp:33