rhi_present_mode.h

Go to the documentation of this file.

/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright The KiCad Developers, see AUTHORS.txt for contributors.
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef RHI_PRESENT_MODE_H
#define RHI_PRESENT_MODE_H
 
#include <algorithm>
#include <chrono>
#include <cstdint>
#include <optional>
#include <string>
#include <vector>
 

constexpr int RHI_PRESENTS_IN_FLIGHT = 2;
 

enum class RHI_PRESENT_MODE : uint8_t
{
    FIFO,       
    MAILBOX,    
    IMMEDIATE   
};
 

inline RHI_PRESENT_MODE RhiChoosePresentMode( const std::vector<RHI_PRESENT_MODE>& aOffered, bool aComposited,
                                              bool aImmediateUnderCompositor = false )
{
    auto offered = [&]( RHI_PRESENT_MODE aMode )
    {
        return std::find( aOffered.begin(), aOffered.end(), aMode ) != aOffered.end();
    };
 
    if( aComposited && aImmediateUnderCompositor && offered( RHI_PRESENT_MODE::IMMEDIATE ) )
        return RHI_PRESENT_MODE::IMMEDIATE;
 
    if( offered( RHI_PRESENT_MODE::MAILBOX ) )
        return RHI_PRESENT_MODE::MAILBOX;
 
    if( aComposited && offered( RHI_PRESENT_MODE::IMMEDIATE ) )
        return RHI_PRESENT_MODE::IMMEDIATE;
 
    return RHI_PRESENT_MODE::FIFO;
}
 

template <typename TIME_POINT>
TIME_POINT RhiNextFrameAt( TIME_POINT aFrameStart, double aRefreshHz, std::optional<TIME_POINT> aVblank )
{
    using DURATION = typename TIME_POINT::duration;
 
    const DURATION period = std::chrono::round<DURATION>( std::chrono::duration<double>( 1.0 / aRefreshHz ) );
 
    if( !aVblank || period <= DURATION::zero() )
        return aFrameStart + period;
 
    const DURATION since = aFrameStart - *aVblank;
    auto           refreshes = since / period;

    if( since < DURATION::zero() && refreshes * period != since )
        --refreshes;
 
    return *aVblank + ( refreshes + 1 ) * period;
}
 
 
#endif // RHI_PRESENT_MODE_H