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LibPDF: Extract reference bitpacking into dedicated class

This commit is contained in:
Ben Wiederhake 2021-09-18 17:15:14 +02:00 committed by Ali Mohammad Pur
parent da170997d5
commit d344253b08
3 changed files with 52 additions and 16 deletions

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/*
* Copyright (c) 2021, Matthew Olsson <mattco@serenityos.org>
* Copyright (c) 2021, Ben Wiederhake <BenWiederhake.GitHub@gmx.de>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Types.h>
namespace PDF {
class Reference {
// We store refs as u32, with 18 bits for the index and 14 bits for the
// generation index. The generation index is stored in the higher bits.
// This may need to be rethought later, as the max generation index is
// 2^16 and the max for the object index is probably 2^32 (I don't know
// exactly)
static constexpr auto MAX_REF_INDEX = (1 << 19) - 1; // 2 ^ 19 - 1
static constexpr auto MAX_REF_GENERATION_INDEX = (1 << 15) - 1; // 2 ^ 15 - 1
public:
Reference(u32 index, u32 generation_index)
{
VERIFY(index < MAX_REF_INDEX);
VERIFY(generation_index < MAX_REF_GENERATION_INDEX);
m_combined = (generation_index << 14) | index;
}
[[nodiscard]] ALWAYS_INLINE u32 as_ref_index() const
{
return m_combined & 0x3ffff;
}
[[nodiscard]] ALWAYS_INLINE u32 as_ref_generation_index() const
{
return m_combined >> 18;
}
private:
u32 m_combined;
};
}