/* * Copyright (C) 2020 Apple Inc. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF * THE POSSIBILITY OF SUCH DAMAGE. */ #include "config.h" #include "DisplayListWriterHandle.h" #include <wtf/CheckedArithmetic.h> namespace WebKit { using namespace WebCore; size_t DisplayListWriterHandle::advance(size_t amount) { m_writableOffset = (CheckedSize { m_writableOffset } + amount).unsafeGet(); return (CheckedSize { header().unreadBytes.exchangeAdd(amount) } + amount).unsafeGet(); } size_t DisplayListWriterHandle::availableCapacity() const { if (UNLIKELY(sharedMemory().size() < writableOffset())) RELEASE_ASSERT_NOT_REACHED(); return sharedMemory().size() - writableOffset(); } DisplayList::ItemBufferHandle DisplayListWriterHandle::createHandle() const { return { identifier(), data() + writableOffset(), availableCapacity() }; } bool DisplayListWriterHandle::moveWritableOffsetToStartIfPossible() { if (m_writableOffset <= SharedDisplayListHandle::headerSize()) { RELEASE_ASSERT(m_writableOffset == SharedDisplayListHandle::headerSize()); return true; } if (unreadBytes()) return false; m_writableOffset = SharedDisplayListHandle::headerSize(); return true; } } // namespace WebKit