/*
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* Copyright 2006 The Android Open Source Project
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkDescriptor_DEFINED
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#define SkDescriptor_DEFINED
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#include <memory>
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#include "SkMacros.h"
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#include "SkNoncopyable.h"
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#include "SkScalerContext.h"
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class SkDescriptor : SkNoncopyable {
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public:
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static size_t ComputeOverhead(int entryCount) {
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SkASSERT(entryCount >= 0);
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return sizeof(SkDescriptor) + entryCount * sizeof(Entry);
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}
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static std::unique_ptr<SkDescriptor> Alloc(size_t length);
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// Ensure the unsized delete is called.
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void operator delete(void* p);
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void init() {
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fLength = sizeof(SkDescriptor);
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fCount = 0;
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}
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uint32_t getLength() const { return fLength; }
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void* addEntry(uint32_t tag, size_t length, const void* data = nullptr);
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void computeChecksum();
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#ifdef SK_DEBUG
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void assertChecksum() const {
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SkASSERT(SkDescriptor::ComputeChecksum(this) == fChecksum);
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}
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#endif
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const void* findEntry(uint32_t tag, uint32_t* length) const;
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std::unique_ptr<SkDescriptor> copy() const;
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// This assumes that all memory added has a length that is a multiple of 4. This is checked
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// by the assert in addEntry.
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bool operator==(const SkDescriptor& other) const;
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bool operator!=(const SkDescriptor& other) const { return !(*this == other); }
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uint32_t getChecksum() const { return fChecksum; }
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struct Entry {
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uint32_t fTag;
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uint32_t fLen;
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};
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#ifdef SK_DEBUG
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uint32_t getCount() const { return fCount; }
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#endif
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private:
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// private so no one can create one except our factories
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SkDescriptor() = default;
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static uint32_t ComputeChecksum(const SkDescriptor* desc);
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uint32_t fChecksum; // must be first
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uint32_t fLength; // must be second
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uint32_t fCount;
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};
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class SkAutoDescriptor : SkNoncopyable {
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public:
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SkAutoDescriptor();
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SkAutoDescriptor(size_t size);
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SkAutoDescriptor(const SkDescriptor& desc);
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SkAutoDescriptor(SkAutoDescriptor&&) = delete;
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SkAutoDescriptor& operator =(SkAutoDescriptor&&) = delete;
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~SkAutoDescriptor();
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void reset(size_t size);
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void reset(const SkDescriptor& desc);
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SkDescriptor* getDesc() const { SkASSERT(fDesc); return fDesc; }
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private:
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void free();
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static constexpr size_t kStorageSize
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= sizeof(SkDescriptor)
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+ sizeof(SkDescriptor::Entry) + sizeof(SkScalerContextRec) // for rec
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+ sizeof(SkDescriptor::Entry) + sizeof(void*) // for typeface
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+ 32; // slop for occasional small extras
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SkDescriptor* fDesc{nullptr};
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std::aligned_storage<kStorageSize, alignof(uint32_t)>::type fStorage;
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};
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#endif //SkDescriptor_DEFINED
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