125 lines
5.0 KiB
C++
125 lines
5.0 KiB
C++
#pragma once
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////////////////////////////////////////////////////////////////////////////////
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// The MIT License (MIT)
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//
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// Copyright (c) 2018 Nicholas Frechette & Animation Compression Library contributors
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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////////////////////////////////////////////////////////////////////////////////
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#include "acl/core/impl/compiler_utils.h"
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#include "acl/core/memory_utils.h"
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#include <cstdint>
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ACL_IMPL_FILE_PRAGMA_PUSH
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namespace acl
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{
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////////////////////////////////////////////////////////////////////////////////
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// Represents an invalid pointer offset, used by 'ptr_offset'.
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////////////////////////////////////////////////////////////////////////////////
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struct invalid_ptr_offset final {};
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////////////////////////////////////////////////////////////////////////////////
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// A type safe pointer offset.
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//
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// This class only wraps an integer of the 'offset_type' type and adds type safety
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// by only casting to 'data_type'.
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////////////////////////////////////////////////////////////////////////////////
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template<typename data_type, typename offset_type>
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class ptr_offset
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{
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public:
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////////////////////////////////////////////////////////////////////////////////
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// Constructs a valid but empty offset.
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constexpr ptr_offset() : m_value(0) {}
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////////////////////////////////////////////////////////////////////////////////
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// Constructs a valid offset with the specified value.
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constexpr ptr_offset(size_t value) : m_value(safe_static_cast<offset_type>(value)) {}
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////////////////////////////////////////////////////////////////////////////////
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// Constructs an invalid offset.
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constexpr ptr_offset(invalid_ptr_offset) : m_value(k_invalid_value) {}
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////////////////////////////////////////////////////////////////////////////////
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// Adds this offset to the provided pointer.
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template<typename BaseType>
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inline data_type* add_to(BaseType* ptr) const
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{
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ACL_ASSERT(is_valid(), "Invalid ptr_offset!");
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return add_offset_to_ptr<data_type>(ptr, m_value);
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}
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////////////////////////////////////////////////////////////////////////////////
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// Adds this offset to the provided pointer.
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template<typename BaseType>
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inline const data_type* add_to(const BaseType* ptr) const
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{
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ACL_ASSERT(is_valid(), "Invalid ptr_offset!");
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return add_offset_to_ptr<const data_type>(ptr, m_value);
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}
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////////////////////////////////////////////////////////////////////////////////
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// Adds this offset to the provided pointer or returns nullptr if the offset is invalid.
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template<typename BaseType>
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inline data_type* safe_add_to(BaseType* ptr) const
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{
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return is_valid() ? add_offset_to_ptr<data_type>(ptr, m_value) : nullptr;
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}
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////////////////////////////////////////////////////////////////////////////////
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// Adds this offset to the provided pointer or returns nullptr if the offset is invalid.
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template<typename BaseType>
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inline const data_type* safe_add_to(const BaseType* ptr) const
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{
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return is_valid() ? add_offset_to_ptr<data_type>(ptr, m_value) : nullptr;
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}
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////////////////////////////////////////////////////////////////////////////////
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// Coercion operator to the underlying 'offset_type'.
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constexpr operator offset_type() const { return m_value; }
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////////////////////////////////////////////////////////////////////////////////
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// Returns true if the offset is valid.
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constexpr bool is_valid() const { return m_value != k_invalid_value; }
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private:
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// Value representing an invalid offset
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static constexpr offset_type k_invalid_value = std::numeric_limits<offset_type>::max();
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// Actual offset value.
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offset_type m_value;
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};
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////////////////////////////////////////////////////////////////////////////////
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// A 16 bit offset.
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template<typename data_type>
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using ptr_offset16 = ptr_offset<data_type, uint16_t>;
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////////////////////////////////////////////////////////////////////////////////
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// A 32 bit offset.
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template<typename data_type>
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using ptr_offset32 = ptr_offset<data_type, uint32_t>;
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}
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ACL_IMPL_FILE_PRAGMA_POP
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