src/backends/reference/workloads/BaseIterator.hpp

//
// Copyright © 2017 Arm Ltd. All rights reserved.
// SPDX-License-Identifier: MIT
//

#pragma once

#include <armnn/TypesUtils.hpp>
#include <armnn/utility/Assert.hpp>
#include <armnn/utility/IgnoreUnused.hpp>
#include <armnnUtils/FloatingPointConverter.hpp>

#include <ResolveType.hpp>

namespace armnn
{

class BaseIterator
{
public:
    BaseIterator() {}

    virtual ~BaseIterator() {}

    virtual BaseIterator& SetIndex(unsigned int index, unsigned int axisIndex = 0) = 0;

    virtual BaseIterator& operator++() = 0;

    virtual BaseIterator& operator+=(const unsigned int increment) = 0;

    virtual BaseIterator& operator-=(const unsigned int increment) = 0;

    virtual BaseIterator& operator[](const unsigned int index) = 0;
};

template<typename IType>
class Decoder : public BaseIterator
{
public:
    Decoder() {}

    virtual ~Decoder() {}

    virtual void Reset(void*) = 0;

    virtual IType Get() const = 0;

    virtual std::vector<float>
    DecodeTensor(const TensorShape &tensorShape,
                 const unsigned int channelMultiplier = 1,
                 bool isDepthwise = false) = 0;
};

template<typename IType>
class Encoder : public BaseIterator
{
public:
    Encoder() {}

    virtual ~Encoder() {}

    virtual void Reset(void*) = 0;

    virtual void Set(IType right) = 0;

    virtual IType Get() const = 0;
};

template<typename T, typename Base>
class TypedIterator : public Base
{
public:
    TypedIterator(T* data = nullptr)
        : m_Iterator(data), m_Start(data)
    {}

    void Reset(void* data) override
    {
        m_Iterator = reinterpret_cast<T*>(data);
        m_Start = m_Iterator;
    }

    TypedIterator& operator++() override
    {
        ARMNN_ASSERT(m_Iterator);
        ++m_Iterator;
        return *this;
    }

    TypedIterator& operator+=(const unsigned int increment) override
    {
        ARMNN_ASSERT(m_Iterator);
        m_Iterator += increment;
        return *this;
    }

    TypedIterator& operator-=(const unsigned int increment) override
    {
        ARMNN_ASSERT(m_Iterator);
        m_Iterator -= increment;
        return *this;
    }

    TypedIterator& operator[](const unsigned int index) override
    {
        ARMNN_ASSERT(m_Iterator);
        m_Iterator = m_Start + index;
        return *this;
    }

    TypedIterator& SetIndex(unsigned int index, unsigned int axisIndex = 0) override
    {
        IgnoreUnused(axisIndex);
        ARMNN_ASSERT(m_Iterator);
        m_Iterator = m_Start + index;
        return *this;
    }

protected:
    T* m_Iterator;
    T* m_Start;
};

class QASymm8Decoder : public TypedIterator<const uint8_t, Decoder<float>>
{
public:
    QASymm8Decoder(const uint8_t* data, const float scale, const int32_t offset)
        : TypedIterator(data), m_Scale(scale), m_Offset(offset) {}

    QASymm8Decoder(const float scale, const int32_t offset)
        : QASymm8Decoder(nullptr, scale, offset) {}

    float Get() const override
    {
        return armnn::Dequantize(*m_Iterator, m_Scale, m_Offset);
    }
    std::vector<float> DecodeTensor (const TensorShape& tensorShape,
                                     const unsigned int channelMultiplier,
                                     const bool isDepthwise) override
    {
        IgnoreUnused(channelMultiplier, isDepthwise);

        const unsigned int size = tensorShape.GetNumElements();
        std::vector<float> decodedTensor;
        decodedTensor.reserve(size);

        for (uint32_t i = 0; i < size; ++i)
        {
            this->operator[](i);
            decodedTensor.emplace_back(armnn::Dequantize(*m_Iterator, m_Scale, m_Offset));
        }

        return decodedTensor;
    }

private:

    const float m_Scale;
    const int32_t m_Offset;
};

class QASymmS8Decoder : public TypedIterator<const int8_t, Decoder<float>>
{
public:
    QASymmS8Decoder(const int8_t* data, const float scale, const int32_t offset)
        : TypedIterator(data), m_Scale(scale), m_Offset(offset) {}

    QASymmS8Decoder(const float scale, const int32_t offset)
        : QASymmS8Decoder(nullptr, scale, offset) {}

    float Get() const override
    {
        return armnn::Dequantize(*m_Iterator, m_Scale, m_Offset);
    }
    std::vector<float> DecodeTensor (const TensorShape& tensorShape,
                                     const unsigned int channelMultiplier,
                                     const bool isDepthwise) override
    {
        IgnoreUnused(channelMultiplier, isDepthwise);

        const unsigned int size = tensorShape.GetNumElements();
        std::vector<float> decodedTensor;
        decodedTensor.reserve(size);

        for (uint32_t i = 0; i < size; ++i)
        {
            this->operator[](i);
            decodedTensor.emplace_back(armnn::Dequantize(*m_Iterator, m_Scale, m_Offset));
        }

        return decodedTensor;
    }

private:
    const float m_Scale;
    const int32_t m_Offset;

};

class QSymmS8Decoder : public TypedIterator<const int8_t, Decoder<float>>
{
public:
    QSymmS8Decoder(const int8_t* data, const float scale, const int32_t offset)
            : TypedIterator(data), m_Scale(scale), m_Offset(offset) {}

    QSymmS8Decoder(const float scale, const int32_t offset)
            : QSymmS8Decoder(nullptr, scale, offset) {}

    float Get() const override
    {
        return armnn::Dequantize(*m_Iterator, m_Scale, m_Offset);
    }
    std::vector<float> DecodeTensor (const TensorShape& tensorShape,
                                     const unsigned int channelMultiplier,
                                     const bool isDepthwise) override
    {
        IgnoreUnused(channelMultiplier, isDepthwise);

        const unsigned int size = tensorShape.GetNumElements();
        std::vector<float> decodedTensor;
        decodedTensor.reserve(size);

        for (uint32_t i = 0; i < size; ++i)
        {
            this->operator[](i);
            decodedTensor.emplace_back(armnn::Dequantize(*m_Iterator, m_Scale, m_Offset));
        }

        return decodedTensor;
    }

private:
    const float m_Scale;
    const int32_t m_Offset;

};

class QSymm16Decoder : public TypedIterator<const int16_t, Decoder<float>>
{
public:
    QSymm16Decoder(const int16_t* data, const float scale, const int32_t offset)
        : TypedIterator(data), m_Scale(scale), m_Offset(offset) {}

    QSymm16Decoder(const float scale, const int32_t offset)
        : QSymm16Decoder(nullptr, scale, offset) {}

    float Get() const override
    {
        return armnn::Dequantize(*m_Iterator, m_Scale, m_Offset);
    }
    std::vector<float> DecodeTensor (const TensorShape& tensorShape,
                                     const unsigned int channelMultiplier,
                                     const bool isDepthwise) override
    {
        IgnoreUnused(channelMultiplier, isDepthwise);

        const unsigned int size = tensorShape.GetNumElements();
        std::vector<float> decodedTensor;
        decodedTensor.reserve(size);

        for (uint32_t i = 0; i < size; ++i)
        {
            this->operator[](i);
            decodedTensor.emplace_back(armnn::Dequantize(*m_Iterator, m_Scale, m_Offset));
        }

        return decodedTensor;
    }

private:
    const float m_Scale;
    const int32_t m_Offset;

};

class BFloat16Decoder : public TypedIterator<const BFloat16, Decoder<float>>
{
public:
    BFloat16Decoder(const BFloat16* data)
        : TypedIterator(data) {}

    BFloat16Decoder()
        : BFloat16Decoder(nullptr) {}

    float Get() const override
    {
        float val = 0.f;
        armnnUtils::FloatingPointConverter::ConvertBFloat16ToFloat32(m_Iterator, 1, &val);
        return val;
    }
    std::vector<float> DecodeTensor (const TensorShape& tensorShape,
                                     const unsigned int channelMultiplier,
                                     const bool isDepthwise) override
    {
        IgnoreUnused(channelMultiplier, isDepthwise);

        const unsigned int size = tensorShape.GetNumElements();
        std::vector<float> decodedTensor;
        decodedTensor.reserve(size);

        for (uint32_t i = 0; i < size; ++i)
        {
            this->operator[](i);

            float val = 0.f;
            armnnUtils::FloatingPointConverter::ConvertBFloat16ToFloat32(m_Iterator, 1, &val);
            decodedTensor.emplace_back(val);
        }

        return decodedTensor;
    }

};

class Float16Decoder : public TypedIterator<const Half, Decoder<float>>
{
public:
    Float16Decoder(const Half* data)
        : TypedIterator(data) {}

    Float16Decoder()
        : Float16Decoder(nullptr) {}

    float Get() const override
    {
        float val = 0.f;
        armnnUtils::FloatingPointConverter::ConvertFloat16To32(m_Iterator, 1, &val);
        return val;
    }
    std::vector<float> DecodeTensor (const TensorShape& tensorShape,
                                     const unsigned int channelMultiplier,
                                     const bool isDepthwise) override
    {
        IgnoreUnused(channelMultiplier, isDepthwise);

        const unsigned int size = tensorShape.GetNumElements();
        std::vector<float> decodedTensor;
        decodedTensor.reserve(size);

        for (uint32_t i = 0; i < size; ++i)
        {
            float val = 0.f;
            this->operator[](i);
            armnnUtils::FloatingPointConverter::ConvertFloat16To32(m_Iterator, 1, &val);
            decodedTensor.emplace_back(val);
        }

        return decodedTensor;
    }


};

class Float32Decoder : public TypedIterator<const float, Decoder<float>>
{
public:
    Float32Decoder(const float* data)
        : TypedIterator(data) {}

    Float32Decoder()
        : Float32Decoder(nullptr) {}

    float Get() const override
    {
        return *m_Iterator;
    }
    std::vector<float> DecodeTensor (const TensorShape& tensorShape,
                                     const unsigned int channelMultiplier,
                                     const bool isDepthwise) override
    {
        IgnoreUnused(channelMultiplier, isDepthwise);
        const unsigned int size = tensorShape.GetNumElements();
        std::vector<float> decodedTensor;

        decodedTensor.reserve(size);
        decodedTensor.assign(m_Start, m_Start + size);

        return decodedTensor;
    }
};

class ScaledInt32Decoder : public TypedIterator<const int32_t, Decoder<float>>
{
public:
    ScaledInt32Decoder(const int32_t* data, const float scale)
        : TypedIterator(data), m_Scale(scale) {}

    ScaledInt32Decoder(const float scale)
        : ScaledInt32Decoder(nullptr, scale) {}

    float Get() const override
    {
        return static_cast<float>(*m_Iterator) * m_Scale;
    }
    std::vector<float> DecodeTensor (const TensorShape& tensorShape,
                                     const unsigned int channelMultiplier,
                                     const bool isDepthwise) override
    {
        IgnoreUnused(channelMultiplier, isDepthwise);

        const unsigned int size = tensorShape.GetNumElements();
        std::vector<float> decodedTensor;
        decodedTensor.reserve(size);

        for (uint32_t i = 0; i < size; ++i)
        {
            this->operator[](i);
            decodedTensor.emplace_back(static_cast<float>(*m_Iterator) * m_Scale);
        }

        return decodedTensor;
    }

private:
    const float m_Scale;

};

class Int32Decoder : public TypedIterator<const int32_t, Decoder<float>>
{
public:
    Int32Decoder(const int32_t* data)
        : TypedIterator(data) {}

    Int32Decoder()
        : Int32Decoder(nullptr) {}

    float Get() const override
    {
        return static_cast<float>(*m_Iterator);
    }
    std::vector<float> DecodeTensor (const TensorShape& tensorShape,
                                     const unsigned int channelMultiplier,
                                     const bool isDepthwise) override
    {
        IgnoreUnused(channelMultiplier, isDepthwise);

        const unsigned int size = tensorShape.GetNumElements();
        std::vector<float> decodedTensor;
        decodedTensor.reserve(size);

        for (uint32_t i = 0; i < size; ++i)
        {
            this->operator[](i);
            decodedTensor.emplace_back(static_cast<float>(*m_Iterator));
        }

        return decodedTensor;
    }
};

class Int32ToInt32tDecoder : public TypedIterator<const int32_t, Decoder<int32_t>>
{
public:
    Int32ToInt32tDecoder(const int32_t* data)
            : TypedIterator(data){}

    Int32ToInt32tDecoder()
            : Int32ToInt32tDecoder(nullptr) {}

    int32_t Get() const override
    {
        return *m_Iterator;
    }
    std::vector<float> DecodeTensor (const TensorShape& tensorShape,
                                     const unsigned int channelMultiplier,
                                     const bool isDepthwise) override
    {
        IgnoreUnused(channelMultiplier, isDepthwise);

        const unsigned int size = tensorShape.GetNumElements();
        std::vector<float> decodedTensor;
        decodedTensor.reserve(size);

        for (uint32_t i = 0; i < size; ++i)
        {
            this->operator[](i);
            decodedTensor.emplace_back(*m_Iterator);
        }

        return decodedTensor;
    }
};

class BooleanDecoder : public TypedIterator<const uint8_t, Decoder<float>>
{
public:
    BooleanDecoder(const uint8_t* data)
            : TypedIterator(data) {}

    BooleanDecoder()
            : BooleanDecoder(nullptr) {}

    float Get() const override
    {
        return *m_Iterator;
    }
    std::vector<float> DecodeTensor (const TensorShape& tensorShape,
                                     const unsigned int channelMultiplier,
                                     const bool isDepthwise) override
    {
        IgnoreUnused(channelMultiplier, isDepthwise);

        const unsigned int size = tensorShape.GetNumElements();
        std::vector<float> decodedTensor;
        decodedTensor.reserve(size);

        for (uint32_t i = 0; i < size; ++i)
        {
            this->operator[](i);
            decodedTensor.emplace_back(*m_Iterator);
        }

        return decodedTensor;
    }
};

class QASymm8Encoder : public TypedIterator<uint8_t, Encoder<float>>
{
public:
    QASymm8Encoder(uint8_t* data, const float scale, const int32_t offset)
        : TypedIterator(data), m_Scale(scale), m_Offset(offset) {}

    QASymm8Encoder(const float scale, const int32_t offset)
        : QASymm8Encoder(nullptr, scale, offset) {}

    void Set(float right) override
    {
        *m_Iterator = armnn::Quantize<uint8_t>(right, m_Scale, m_Offset);
    }

    float Get() const override
    {
        return armnn::Dequantize(*m_Iterator, m_Scale, m_Offset);
    }

private:
    const float m_Scale;
    const int32_t m_Offset;
};

class QASymmS8Encoder : public TypedIterator<int8_t, Encoder<float>>
{
public:
    QASymmS8Encoder(int8_t* data, const float scale, const int32_t offset)
        : TypedIterator(data), m_Scale(scale), m_Offset(offset) {}

    QASymmS8Encoder(const float scale, const int32_t offset)
        : QASymmS8Encoder(nullptr, scale, offset) {}

    void Set(float right) override
    {
        *m_Iterator = armnn::Quantize<int8_t>(right, m_Scale, m_Offset);
    }

    float Get() const override
    {
        return armnn::Dequantize(*m_Iterator, m_Scale, m_Offset);
    }

private:
    const float m_Scale;
    const int32_t m_Offset;
};

class QSymmS8Encoder : public TypedIterator<int8_t, Encoder<float>>
{
public:
    QSymmS8Encoder(int8_t* data, const float scale, const int32_t offset)
            : TypedIterator(data), m_Scale(scale), m_Offset(offset) {}

    QSymmS8Encoder(const float scale, const int32_t offset)
            : QSymmS8Encoder(nullptr, scale, offset) {}

    void Set(float right) override
    {
        *m_Iterator = armnn::Quantize<int8_t>(right, m_Scale, m_Offset);
    }

    float Get() const override
    {
        return armnn::Dequantize(*m_Iterator, m_Scale, m_Offset);
    }

private:
    const float m_Scale;
    const int32_t m_Offset;
};

class QSymm16Encoder : public TypedIterator<int16_t, Encoder<float>>
{
public:
    QSymm16Encoder(int16_t* data, const float scale, const int32_t offset)
        : TypedIterator(data), m_Scale(scale), m_Offset(offset) {}

    QSymm16Encoder(const float scale, const int32_t offset)
        : QSymm16Encoder(nullptr, scale, offset) {}

    void Set(float right) override
    {
        *m_Iterator = armnn::Quantize<int16_t>(right, m_Scale, m_Offset);
    }

    float Get() const override
    {
        return armnn::Dequantize(*m_Iterator, m_Scale, m_Offset);
    }

private:
    const float m_Scale;
    const int32_t m_Offset;
};

class BFloat16Encoder : public TypedIterator<armnn::BFloat16, Encoder<float>>
{
public:
    BFloat16Encoder(armnn::BFloat16* data)
        : TypedIterator(data) {}

    BFloat16Encoder()
        : BFloat16Encoder(nullptr) {}

    void Set(float right) override
    {
        armnnUtils::FloatingPointConverter::ConvertFloat32ToBFloat16(&right, 1, m_Iterator);
    }

    float Get() const override
    {
        float val = 0.f;
        armnnUtils::FloatingPointConverter::ConvertBFloat16ToFloat32(m_Iterator, 1, &val);
        return val;
    }
};

class Float16Encoder : public TypedIterator<Half, Encoder<float>>
{
public:
    Float16Encoder(Half* data)
        : TypedIterator(data) {}

    Float16Encoder()
        : Float16Encoder(nullptr) {}

    void Set(float right) override
    {
        armnnUtils::FloatingPointConverter::ConvertFloat32To16(&right, 1, m_Iterator);
    }

    float Get() const override
    {
        float val = 0.f;
        armnnUtils::FloatingPointConverter::ConvertFloat16To32(m_Iterator, 1, &val);
        return val;
    }
};

class Float32Encoder : public TypedIterator<float, Encoder<float>>
{
public:
    Float32Encoder(float* data)
        : TypedIterator(data) {}

    Float32Encoder()
        : Float32Encoder(nullptr) {}

    void Set(float right) override
    {
        *m_Iterator = right;
    }

    float Get() const override
    {
        return *m_Iterator;
    }
};

class Int32Encoder : public TypedIterator<int32_t, Encoder<float>>
{
public:
    Int32Encoder(int32_t* data)
        : TypedIterator(data) {}

    Int32Encoder()
        : Int32Encoder(nullptr) {}

    void Set(float right) override
    {
        *m_Iterator = static_cast<int32_t>(right);
    }

    float Get() const override
    {
        return static_cast<float>(*m_Iterator);
    }
};

class Int32ToInt32tEncoder : public TypedIterator<int32_t, Encoder<int32_t>>
{
public:
    Int32ToInt32tEncoder(int32_t* data)
        : TypedIterator(data){}

    Int32ToInt32tEncoder()
        : Int32ToInt32tEncoder(nullptr) {}

    void Set(int32_t right) override
    {
        *m_Iterator = right;
    }

    int32_t Get() const override
    {
        return *m_Iterator;
    }
};

class BooleanEncoder : public TypedIterator<uint8_t, Encoder<bool>>
{
public:
    BooleanEncoder(uint8_t* data)
        : TypedIterator(data) {}

    BooleanEncoder()
        : BooleanEncoder(nullptr) {}

    void Set(bool right) override
    {
        *m_Iterator = right;
    }

    bool Get() const override
    {
        return *m_Iterator;
    }
};

// PerAxisIterator for per-axis quantization
template<typename T, typename Base>
class PerAxisIterator : public Base
{
public:
    // axisFactor is used to calculate channelStep
    PerAxisIterator(T* data = nullptr, unsigned int axisFactor = 0)
        : m_Iterator(data), m_Start(data), m_AxisIndex(0), m_AxisFactor(axisFactor)
    {}

    // This should be called to set index for per-axis Encoder/Decoder
    PerAxisIterator& SetIndex(unsigned int index, unsigned int axisIndex) override
    {
         ARMNN_ASSERT(m_Iterator);
         m_Iterator = m_Start + index;
         m_AxisIndex = axisIndex;
         return *this;
    }

    void Reset(void* data) override
    {
        m_Iterator = reinterpret_cast<T*>(data);
        m_Start = m_Iterator;
        m_AxisIndex = 0;
    }

    PerAxisIterator& operator++() override
    {
        ARMNN_ASSERT(m_Iterator);
        ++m_Iterator;
        m_AxisIndex = static_cast<unsigned int>(*m_Iterator) % m_AxisFactor;
        return *this;
    }

    PerAxisIterator& operator+=(const unsigned int increment) override
    {
        ARMNN_ASSERT(m_Iterator);
        m_Iterator += increment;
        m_AxisIndex = static_cast<unsigned int>(*m_Iterator) % m_AxisFactor;
        return *this;
    }

    PerAxisIterator& operator-=(const unsigned int decrement) override
    {
        ARMNN_ASSERT(m_Iterator);
        m_Iterator -= decrement;
        m_AxisIndex = static_cast<unsigned int>(*m_Iterator) % m_AxisFactor;
        return *this;
    }

    PerAxisIterator& operator[](const unsigned int index) override
    {
        ARMNN_ASSERT(m_Iterator);
        m_Iterator = m_Start + index;
        m_AxisIndex = static_cast<unsigned int>(*m_Iterator) % m_AxisFactor;
        return *this;
    }

    protected:
        T* m_Iterator;
        T* m_Start;
        unsigned int m_AxisIndex;
        unsigned int m_AxisFactor;
};

class QSymm8PerAxisDecoder : public PerAxisIterator<const int8_t, Decoder<float>>
{
public:
    QSymm8PerAxisDecoder(const int8_t* data, const std::vector<float>& scale, unsigned int axisFactor)
        : PerAxisIterator(data, axisFactor), m_Scales(scale) {}

    float Get() const override
    {
        return armnn::Dequantize(*m_Iterator, m_Scales[m_AxisIndex], 0);
    }

    // Get scale of the current value
    float GetScale() const
    {
        return m_Scales[m_AxisIndex];
    }

    std::vector<float> DecodeTensor(const TensorShape &tensorShape,
                                    const unsigned int channelMultiplier,
                                    bool isDepthwise) override
    {
        const uint32_t size = tensorShape.GetNumElements();
        const uint32_t scaleSize = static_cast<uint32_t>(m_Scales.size());

        const uint32_t stepSize = isDepthwise ?
                                  tensorShape[2] * tensorShape[3] : tensorShape.GetNumElements() / tensorShape[0];

        const uint32_t stepNum = size / (stepSize * channelMultiplier);
        uint32_t scale;

        std::vector<float> decodedTensor;
        decodedTensor.reserve(size);

        // channelMultiplier is only used in depthwise convolutions and in other cases will have no effect
        // stepSize is the length of a contiguous area sharing a quantization scale within a tensor
        // stepNum is the number of those steps/blocks in the tensor
        for (uint32_t mult = 0; mult < channelMultiplier; ++mult)
        {
            for (uint32_t step = 0; step < stepNum; ++step)
            {
                scale = (channelMultiplier * step + mult) % scaleSize;
                for (uint32_t i = 0; i < stepSize; ++i)
                {
                    unsigned int index = mult * stepSize * channelMultiplier +
                                         step * stepSize + i;
                    this->operator[](index);
                    decodedTensor.emplace_back(armnn::Dequantize(*m_Iterator, m_Scales[scale], 0));
                }
            }
        }
        return decodedTensor;
    }

private:
    std::vector<float> m_Scales;
};

class QSymm8PerAxisEncoder : public PerAxisIterator<int8_t, Encoder<float>>
{
public:
    QSymm8PerAxisEncoder(int8_t* data, const std::vector<float>& scale, unsigned int axisFactor)
        : PerAxisIterator(data, axisFactor), m_Scale(scale) {}

    void Set(float right)
    {
        *m_Iterator = armnn::Quantize<int8_t>(right, m_Scale[m_AxisIndex], 0);
    }

    float Get() const
    {
        return armnn::Dequantize(*m_Iterator, m_Scale[m_AxisIndex], 0);
    }

    // Get scale of the current value
    float GetScale() const
    {
        return m_Scale[m_AxisIndex];
    }

private:
    std::vector<float> m_Scale;
};

class ScaledInt32PerAxisDecoder : public PerAxisIterator<const int32_t, Decoder<float>>
{
public:
    ScaledInt32PerAxisDecoder(const int32_t* data, const std::vector<float>& scales, unsigned int axisFactor)
        : PerAxisIterator(data, axisFactor), m_Scales(scales) {}

    float Get() const override
    {
        return armnn::Dequantize(*m_Iterator, m_Scales[m_AxisIndex], 0);
    }

    // Get scale of the current value
    float GetScale() const
    {
        return m_Scales[m_AxisIndex];
    }

    std::vector<float> DecodeTensor(const TensorShape &tensorShape,
                                    const unsigned int channelMultiplier,
                                    bool isDepthwise) override
    {
        const uint32_t size = tensorShape.GetNumElements();
        const uint32_t scaleSize = static_cast<uint32_t>(m_Scales.size());

        const uint32_t stepSize = isDepthwise ?
                                  tensorShape[2] * tensorShape[3] : tensorShape.GetNumElements() / tensorShape[0];

        const uint32_t stepNum = size / (stepSize * channelMultiplier);
        uint32_t scale;

        std::vector<float> decodedTensor;
        decodedTensor.reserve(size);

        // channelMultiplier is only used in depthwise convolutions and in other cases will have no effect
        // stepSize is the length of a contiguous area sharing a quantization scale within a tensor
        // stepNum is the number of those steps/blocks in the tensor
        for (uint32_t mult = 0; mult < channelMultiplier; ++mult)
        {
            for (uint32_t step = 0; step < stepNum; ++step)
            {
                scale = (channelMultiplier * step + mult) % scaleSize;
                for (uint32_t i = 0; i < stepSize; ++i)
                {
                    unsigned int index = mult * stepSize * channelMultiplier +
                                         step * stepSize + i;
                    this->operator[](index);
                    decodedTensor.emplace_back(armnn::Dequantize(*m_Iterator, m_Scales[scale], 0));
                }
            }
        }
        return decodedTensor;
    }

private:
    std::vector<float> m_Scales;
};

} // namespace armnn