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42 lines
1.3 KiB
C++
42 lines
1.3 KiB
C++
// Copyright 2024 Dolphin Emulator Project
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// SPDX-License-Identifier: GPL-2.0-or-later
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#pragma once
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#include <algorithm>
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#include <cstddef>
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#include <span>
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#include <utility>
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#include "Common/CommonTypes.h"
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namespace Common
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{
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// Like std::span::subspan, except undefined behavior is replaced with returning a 0-length span.
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template <class T>
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[[nodiscard]] constexpr std::span<T> SafeSubspan(std::span<T> span, size_t offset,
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size_t count = std::dynamic_extent)
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{
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if (count == std::dynamic_extent || offset > span.size())
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return span.subspan(std::min(offset, span.size()));
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else
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return span.subspan(offset, std::min(count, span.size() - offset));
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}
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// Default-constructs an object of type T, then copies data into it from the specified offset in
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// the specified span. Out-of-bounds reads will be skipped, meaning that specifying a too large
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// offset results in the object partially or entirely remaining default constructed.
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template <class T>
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[[nodiscard]] T SafeSpanRead(std::span<const u8> span, size_t offset)
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{
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static_assert(std::is_trivially_copyable<T>());
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const std::span<const u8> subspan = SafeSubspan(span, offset);
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T result{};
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std::memcpy(&result, subspan.data(), std::min(subspan.size(), sizeof(result)));
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return result;
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}
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} // namespace Common
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