lut.h

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#pragma once
 
/*
LUT - Look up table implementation for various types.
*/
 
#include "fl/allocator.h"
#include "fl/force_inline.h"
#include "fl/ptr.h"
#include <stdint.h>
 
#include "fl/geometry.h"
#include "fl/namespace.h"
 
namespace fl {
 
// LUT holds a look up table to map data from one
// value to another. This can be quite big (1/3rd of the frame buffer)
// so a Referent is used to allow memory sharing.
 
template <typename T> class LUT;
 
typedef LUT<uint16_t> LUT16;
typedef LUT<vec2<uint16_t>> LUTXY16;
typedef LUT<vec2f> LUTXYFLOAT;
typedef LUT<vec3f> LUTXYZFLOAT;
 
FASTLED_SMART_PTR_NO_FWD(LUT16);
FASTLED_SMART_PTR_NO_FWD(LUTXY16);
FASTLED_SMART_PTR_NO_FWD(LUTXYFLOAT);
FASTLED_SMART_PTR_NO_FWD(LUTXYZFLOAT);
 
// Templated lookup table.
template <typename T> class LUT : public fl::Referent {
  public:
    LUT(uint32_t length) : length(length) {
        T *ptr = LargeBlockAllocator<T>::Alloc(length);
        mDataHandle.reset(ptr);
        data = ptr;
    }
    // In this version the data is passed in but not managed by this object.
    LUT(uint32_t length, T *data) : length(length) { this->data = data; }
    ~LUT() {
        LargeBlockAllocator<T>::Free(mDataHandle.release());
        data = mDataHandle.get();
    }
 
    const T &operator[](uint32_t index) const { return data[index]; }
 
    const T &operator[](uint16_t index) const { return data[index]; }
 
    T *getDataMutable() { return data; }
 
    const T *getData() const { return data; }
 
    uint32_t size() const { return length; }
 
    T interp8(uint8_t alpha) {
        if (length == 0)
            return T();
        if (alpha == 0)
            return data[0];
        if (alpha == 255)
            return data[length - 1];
 
        // treat alpha/255 as fraction, scale to [0..length-1]
        uint32_t maxIndex = length - 1;
        uint32_t pos = uint32_t(alpha) * maxIndex; // numerator
        uint32_t idx0 = pos / 255;                 // floor(position)
        uint32_t idx1 = idx0 < maxIndex ? idx0 + 1 : maxIndex;
        uint8_t blend = pos % 255; // fractional part
 
        const T &a = data[idx0];
        const T &b = data[idx1];
        // a + (b-a) * blend/255
        return a + (b - a) * blend / 255;
    }
 
    T interp16(uint16_t alpha) {
        if (length == 0)
            return T();
        if (alpha == 0)
            return data[0];
        if (alpha == 65535)
            return data[length - 1];
 
        // treat alpha/65535 as fraction, scale to [0..length-1]
        uint32_t maxIndex = length - 1;
        uint32_t pos = uint32_t(alpha) * maxIndex; // numerator
        uint32_t idx0 = pos / 65535;               // floor(position)
        uint32_t idx1 = idx0 < maxIndex ? idx0 + 1 : maxIndex;
        uint16_t blend = pos % 65535; // fractional part
 
        const T &a = data[idx0];
        const T &b = data[idx1];
        // a + (b-a) * blend/65535
        return a + (b - a) * blend / 65535;
    }
 
  private:
    fl::scoped_ptr<T> mDataHandle;
    T *data = nullptr;
    uint32_t length;
};
 
} // namespace fl