FrameSource.hh

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#ifndef FRAMESOURCE_HH
#define FRAMESOURCE_HH
 
#include "aligned.hh"
#include "narrow.hh"
#include "xrange.hh"
 
#include <algorithm>
#include <array>
#include <bit>
#include <cassert>
#include <cstdint>
#include <span>
 
namespace openmsx {
 
class FrameSource
{
public:
        using Pixel = uint32_t;
 
        enum class FieldType {
                NONINTERLACED,
                EVEN,
                ODD,
        };
 
        void init(FieldType fieldType_) { fieldType = fieldType_; }
 
        [[nodiscard]] FieldType getField() const {
                return fieldType;
        }
 
        [[nodiscard]] unsigned getHeight() const {
                return height;
        }
 
        [[nodiscard]] virtual unsigned getLineWidth(unsigned line) const = 0;
 
        [[nodiscard]] unsigned getWidth() const {
                assert(height > 0);
                unsigned result = getLineWidth(0);
                for (auto line : xrange(1u, height)) {
                        assert(result == getLineWidth(line)); (void)line;
                }
                return result;
        }
 
        [[nodiscard]] inline Pixel getLineColor(unsigned line) const {
                ALIGNAS_SSE std::array<Pixel, 1280> buf; // large enough for widest line
                return getUnscaledLine(line, buf)[0];
        }
 
        [[nodiscard]] inline std::span<const Pixel> getLine(int line, std::span<Pixel> buf) const
        {
                line = std::clamp(line, 0, narrow<int>(getHeight() - 1));
                auto unscaledLine = getUnscaledLine(line, buf);
                if (unscaledLine.size() == buf.size()) {
                        // Already the correct width.
                        return unscaledLine;
                } else {
                        // slow path, non-inlined
                        // internalData might be equal to buf
                        scaleLine(unscaledLine, buf);
                        return buf;
                }
        }
 
        [[nodiscard]] virtual std::span<const Pixel> getUnscaledLine(
                unsigned line, std::span<Pixel> helpBuf) const = 0;
 
        [[nodiscard]] std::span<const Pixel, 320> getLinePtr320_240(unsigned line, std::span<Pixel, 320> buf) const;
 
        [[nodiscard]] std::span<const Pixel, 640> getLinePtr640_480(unsigned line, std::span<Pixel, 640> buf) const;
 
        [[nodiscard]] std::span<const Pixel, 960> getLinePtr960_720(unsigned line, std::span<Pixel, 960> buf) const;
 
protected:
        FrameSource() = default;
        ~FrameSource() = default;
 
        void setHeight(unsigned height_) { height = height_; }
 
        [[nodiscard]] virtual bool hasContiguousStorage() const {
                return false;
        }
 
        void scaleLine(std::span<const Pixel> in, std::span<Pixel> out) const;
 
private:
        unsigned height;
 
        FieldType fieldType;
};
 
} // namespace openmsx
 
#endif // FRAMESOURCE_HH