89 lines
2.8 KiB
C++
89 lines
2.8 KiB
C++
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// Copyright 2024 The DMBMX2Tools Authors
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// SPDX-License-Identifier: MIT
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#pragma once
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#include <bit>
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#include <base/Types.hpp>
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#include <type_traits>
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#include <span>
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namespace dmtools {
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namespace detail {
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template <class NativeT, class OffsetType>
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constexpr NativeT* CreatePointerFromAddend(void* BasePointer, OffsetType addend) noexcept {
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return std::bit_cast<NativeT*>(static_cast<char*>(BasePointer) + addend);
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}
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} // namespace detail
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/// An "auto-resolving" semi-sweet (/s) pointer type.
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/// This is designed to allow resolving offsets in data for
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/// games written before 64-bit pointers were common/used at all.
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/// This allows looking up data a lot easier :)
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///
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/// [NativeT] is the type of data this would point to
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/// [OffsetType] is the type of data the "pointer" is repressented as
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template <class NativeT, class OffsetType = u32>
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struct OffsetPtr final {
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using Type = std::remove_cvref_t<NativeT>;
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using Pointer = Type*;
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using ConstPointer = const Type*;
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/// Set the offset. Duh!
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constexpr void Set(OffsetType newOffset) noexcept { rawOffset = newOffset; }
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[[nodiscard]] constexpr OffsetType Raw() const noexcept { return rawOffset; }
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[[nodiscard]] constexpr Pointer operator()(void* baseAddr) const noexcept {
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// While yucky, it should show problem areas which aren't checking things
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// immediately rather than read invalid data that might do much worse.
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if(rawOffset == 0)
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return nullptr;
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return detail::CreatePointerFromAddend<Type>(baseAddr, rawOffset);
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}
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template<class NativeU>
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constexpr OffsetPtr<NativeU, OffsetType>& PtrCast() {
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// Safety: The data layout of OffsetPtr<> stays
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// the exact same regardless of the result type, therefore
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// even though this is *techinically* UB (? using bit_cast it shouldn't be ?),
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// this isn't problematic
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return *std::bit_cast<OffsetPtr<NativeU, OffsetType>*>(this);
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}
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private:
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OffsetType rawOffset;
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};
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/// Like OffsetPtr<T> but for arrays of data
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template <class NativeT, class OffsetType = u32>
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struct OffsetArrayPtr final {
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using Type = std::remove_cvref_t<NativeT>;
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using Pointer = Type*;
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using ConstPointer = const Type*;
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using Span = std::span<NativeT>;
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/// Set the offset. Duh!
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constexpr void Set(OffsetType newOffset) noexcept { rawOffset = newOffset; }
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[[nodiscard]] constexpr OffsetType Raw() const noexcept { return rawOffset; }
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[[nodiscard]] constexpr Span operator()(void* baseAddr, OffsetType length) const noexcept {
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// While yucky, it should show problem areas which aren't checking things
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// immediately rather than read invalid data that might do much worse.
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if(rawOffset == 0 || length == 0)
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return {};
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return { detail::CreatePointerFromAddend<Type>(baseAddr, rawOffset), length };
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}
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private:
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OffsetType rawOffset;
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};
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} // namespace ssxtools::core
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