createAndDestroyDeviceObject.cpp

/*
 *  Copyright 2019 Patrick Stotko
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

#include <limits>            // std::numeric_limits
#include <stdgpu/memory.h>   // createDeviceArray, destroyDeviceArray, createHostArray, destroyHostArray
#include <stdgpu/platform.h> // STDGPU_HOST_DEVICE

class Image
{
public:
    Image() = default;

    [[nodiscard]] static Image
    createDeviceObject(const stdgpu::index_t width, const stdgpu::index_t height)
    {
        Image result;

        result._values = createDeviceArray<std::uint8_t>(static_cast<stdgpu::index64_t>(width) *
                                                         static_cast<stdgpu::index64_t>(height));
        result._width = width;
        result._height = height;

        return result;
    }

    static void
    destroyDeviceObject(Image& device_object)
    {
        destroyDeviceArray<std::uint8_t>(device_object._values);
        device_object._width = 0;
        device_object._height = 0;
    }

    [[nodiscard]] static Image
    createHostObject(const stdgpu::index_t width, const stdgpu::index_t height)
    {
        Image result;

        result._values = createHostArray<std::uint8_t>(static_cast<stdgpu::index64_t>(width) *
                                                       static_cast<stdgpu::index64_t>(height));
        result._width = width;
        result._height = height;

        return result;
    }

    static void
    destroyHostObject(Image& host_object)
    {
        destroyHostArray<std::uint8_t>(host_object._values);
        host_object._width = 0;
        host_object._height = 0;
    }

    // Further (static) member functions ...

    STDGPU_HOST_DEVICE std::uint8_t&
    operator()(const stdgpu::index_t x, const stdgpu::index_t y)
    {
        return _values[y * _width + x];
    }

    STDGPU_HOST_DEVICE stdgpu::index_t
    width() const
    {
        return _width;
    }

    STDGPU_HOST_DEVICE stdgpu::index_t
    height() const
    {
        return _height;
    }

private:
    std::uint8_t* _values = nullptr;
    stdgpu::index_t _width = 0;
    stdgpu::index_t _height = 0;
};

void
fill_image(Image image)
{
    const stdgpu::index_t value_bound = static_cast<stdgpu::index_t>(std::numeric_limits<std::uint8_t>::max()) + 1;

    for (stdgpu::index_t i = 0; i < image.width(); ++i)
    {
        for (stdgpu::index_t j = 0; j < image.height(); ++j)
        {
            std::uint8_t value = static_cast<std::uint8_t>((i * i + j * j) % value_bound);

            image(i, j) = value;
        }
    }
}

int
main()
{
    const stdgpu::index_t width = 1920;
    const stdgpu::index_t height = 1080;
    Image image = Image::createHostObject(width, height);

    fill_image(image);

    Image::destroyHostObject(image);
}