| /* |
| * |
| * Copyright (c) 2020 Project CHIP Authors |
| * Copyright (c) 2013-2017 Nest Labs, Inc. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| #pragma once |
| |
| #include <lib/support/StringBuilder.h> |
| #include <lib/support/TypeTraits.h> |
| |
| #include <cstdint> |
| #include <type_traits> |
| |
| namespace chip { |
| namespace TLV { |
| |
| class Tag |
| { |
| public: |
| enum SpecialTagNumber : uint32_t |
| { |
| kContextTagMaxNum = UINT8_MAX, |
| kAnonymousTagNum, |
| kUnknownImplicitTagNum |
| }; |
| |
| Tag() = default; |
| |
| constexpr bool operator==(const Tag & other) const { return mVal == other.mVal; } |
| constexpr bool operator!=(const Tag & other) const { return mVal != other.mVal; } |
| |
| /// Appends the text representation of the tag to the given string builder base. |
| StringBuilderBase & AppendTo(StringBuilderBase & out); |
| |
| private: |
| explicit constexpr Tag(uint64_t val) : mVal(val) {} |
| |
| friend constexpr Tag ProfileTag(uint32_t profileId, uint32_t tagNum); |
| friend constexpr Tag ProfileTag(uint16_t vendorId, uint16_t profileNum, uint32_t tagNum); |
| friend constexpr Tag ContextTag(uint8_t tagNum); |
| friend constexpr Tag CommonTag(uint32_t tagNum); |
| friend constexpr Tag AnonymousTag(); |
| friend constexpr Tag UnknownImplicitTag(); |
| |
| // The following friend functions could be Tag class methods, but it turns out in some cases |
| // they may not be inlined and then passing the tag by argument/value results in smaller code |
| // than passing it by 'this' pointer. This can be worked around by applying 'always_inline' |
| // function attribute, but friend functions are likely a more portable solution. |
| |
| friend constexpr uint32_t ProfileIdFromTag(Tag tag); |
| friend constexpr uint16_t VendorIdFromTag(Tag tag); |
| friend constexpr uint16_t ProfileNumFromTag(Tag tag); |
| friend constexpr uint32_t TagNumFromTag(Tag tag); |
| |
| friend constexpr bool IsProfileTag(Tag tag); |
| friend constexpr bool IsContextTag(Tag tag); |
| friend constexpr bool IsSpecialTag(Tag tag); |
| |
| static constexpr uint32_t kProfileIdShift = 32; |
| static constexpr uint32_t kVendorIdShift = 48; |
| static constexpr uint32_t kProfileNumShift = 32; |
| static constexpr uint32_t kSpecialTagProfileId = 0xFFFFFFFF; |
| |
| // The storage of the tag value uses the following encoding: |
| // |
| // 63 47 31 |
| // +-------------------------------+-------------------------------+----------------------------------------------+ |
| // | Vendor id (bitwise-negated) | Profile num (bitwise-negated) | Tag number | |
| // +-------------------------------+-------------------------------+----------------------------------------------+ |
| // |
| // Vendor id and profile number are bitwise-negated in order to optimize the code size when |
| // using context tags, the most commonly used tags in the SDK. |
| uint64_t mVal; |
| }; |
| |
| enum TLVCommonProfiles |
| { |
| /** |
| * Used to indicate the absence of a profile id in a variable or member. |
| * This is essentially the same as kCHIPProfile_NotSpecified defined in CHIPProfiles.h |
| */ |
| kProfileIdNotSpecified = 0xFFFFFFFF, |
| |
| // TODO: Replace with chip::Profiles::kCHIPProfile_Common |
| kCommonProfileId = 0 |
| }; |
| |
| // TODO: Move to private namespace |
| enum class TLVTagControl : uint8_t |
| { |
| // IMPORTANT: All values here must have no bits in common with specified |
| // values of TLVElementType. |
| Anonymous = 0x00, |
| ContextSpecific = 0x20, |
| CommonProfile_2Bytes = 0x40, |
| CommonProfile_4Bytes = 0x60, |
| ImplicitProfile_2Bytes = 0x80, |
| ImplicitProfile_4Bytes = 0xA0, |
| FullyQualified_6Bytes = 0xC0, |
| FullyQualified_8Bytes = 0xE0 |
| }; |
| |
| template <typename T> |
| inline uint8_t operator>>(TLVTagControl lhs, const T & rhs) |
| { |
| return static_cast<uint8_t>(static_cast<uint8_t>(lhs) >> rhs); |
| } |
| |
| // TODO: Move to private namespace |
| enum |
| { |
| kTLVTagControlMask = 0xE0, |
| kTLVTagControlShift = 5 |
| }; |
| |
| /** |
| * Generates the API representation of a profile-specific TLV tag from a profile id and tag number |
| * |
| * @param[in] profileId The id of the profile within which the tag is defined. |
| * @param[in] tagNum The profile-specific tag number assigned to the tag. |
| * @return A 64-bit integer representing the tag. |
| */ |
| constexpr Tag ProfileTag(uint32_t profileId, uint32_t tagNum) |
| { |
| return Tag((static_cast<uint64_t>(~profileId) << Tag::kProfileIdShift) | tagNum); |
| } |
| |
| /** |
| * Generates the API representation of a profile-specific TLV tag from a vendor id, profile number and tag number |
| * |
| * @param[in] vendorId The id of the vendor that defined the tag. |
| * @param[in] profileNum The vendor assigned number for the profile within which the tag is defined. |
| * @param[in] tagNum The profile-specific tag number assigned to the tag. |
| * @return A 64-bit integer representing the tag. |
| */ |
| constexpr Tag ProfileTag(uint16_t vendorId, uint16_t profileNum, uint32_t tagNum) |
| { |
| constexpr uint32_t kVendorIdShift = Tag::kVendorIdShift - Tag::kProfileIdShift; |
| |
| return ProfileTag((static_cast<uint32_t>(vendorId) << kVendorIdShift) | profileNum, tagNum); |
| } |
| |
| /** |
| * Generates the API representation of a context-specific TLV tag |
| * |
| * @param[in] tagNum The context-specific tag number assigned to the tag. |
| * @return A 64-bit integer representing the tag. |
| */ |
| constexpr Tag ContextTag(uint8_t tagNum) |
| { |
| return ProfileTag(Tag::kSpecialTagProfileId, tagNum); |
| } |
| |
| /** |
| * Also allow using enum class values as context tags. There are four possible |
| * cases when is_enum is true: |
| * |
| * 1) The enum is a scoped enum (enum class) and the underlying type is |
| * uint8_t. Then the is_convertible test will test false, this overload will be |
| * used, to_underlying will return a uint8_t, and everything will work. |
| * 2) The enum is a scoped enum (enum class) and the underlying type is |
| * not uint8_t. Then the is_convertible test will test false, this overload will be |
| * used, to_underlying will return the other type, and -Wconversion will |
| * catch the type mismatch, if it's enabled. |
| * 3) The enum is an old-style enum. Then the is_convertible test will test |
| * true, this overload will be not be used, and the uint8_t overload will be |
| * used instead. The compiler should then catch (at least with sufficient |
| * warnings turned on) if the constant being passed in is too big to fit into |
| * uint8_t. |
| * |
| * Leaving out the is_convertible test, so this overload gets used for old-style |
| * enums, would cause old-style enums where the underlying type is wider than |
| * uint8_t to fail compilation with -Wconversion even if the values are all |
| * inside the uint8_t range, since to_underlying would explicitly return a type |
| * that is wider than uint8_t. |
| */ |
| template <typename T, std::enable_if_t<std::is_enum<T>::value && !std::is_convertible<T, uint8_t>::value, int> = 0> |
| constexpr Tag ContextTag(T tagNum) |
| { |
| return ContextTag(to_underlying(tagNum)); |
| } |
| |
| /** |
| * Generates the API representation of a common profile TLV tag |
| * |
| * @param[in] tagNum The common profile tag number assigned to the tag. |
| * @return A 64-bit integer representing the tag. |
| */ |
| constexpr Tag CommonTag(uint32_t tagNum) |
| { |
| return ProfileTag(kCommonProfileId, tagNum); |
| } |
| |
| /** |
| * A value signifying a TLV element that has no tag (i.e. an anonymous element). |
| */ |
| constexpr Tag AnonymousTag() |
| { |
| return ProfileTag(Tag::kSpecialTagProfileId, Tag::kAnonymousTagNum); |
| } |
| |
| /** |
| * An invalid tag that represents a TLV element decoding error due to unknown implicit profile id. |
| */ |
| constexpr Tag UnknownImplicitTag() |
| { |
| return ProfileTag(Tag::kSpecialTagProfileId, Tag::kUnknownImplicitTagNum); |
| } |
| |
| /** |
| * Returns the profile id from a TLV tag |
| * |
| * @note The behavior of this function is undefined if the supplied tag is not a profile-specific tag. |
| * |
| * @param[in] tag The API representation of a profile-specific TLV tag. |
| * @return The profile id. |
| */ |
| constexpr uint32_t ProfileIdFromTag(Tag tag) |
| { |
| return ~static_cast<uint32_t>(tag.mVal >> Tag::kProfileIdShift); |
| } |
| |
| /** |
| * Returns the vendor id from a TLV tag |
| * |
| * @note The behavior of this function is undefined if the supplied tag is not a profile-specific tag. |
| * |
| * @param[in] tag The API representation of a profile-specific TLV tag. |
| * @return The associated vendor id. |
| */ |
| constexpr uint16_t VendorIdFromTag(Tag tag) |
| { |
| constexpr uint32_t kVendorIdShift = Tag::kVendorIdShift - Tag::kProfileIdShift; |
| |
| return static_cast<uint16_t>(ProfileIdFromTag(tag) >> kVendorIdShift); |
| } |
| |
| /** |
| * Returns the profile number from a TLV tag |
| * |
| * @note The behavior of this function is undefined if the supplied tag is not a profile-specific tag. |
| * |
| * @param[in] tag The API representation of a profile-specific TLV tag. |
| * @return The associated profile number. |
| */ |
| constexpr uint16_t ProfileNumFromTag(Tag tag) |
| { |
| return static_cast<uint16_t>(ProfileIdFromTag(tag)); |
| } |
| |
| /** |
| * Returns the tag number from a TLV tag |
| * |
| * @note The behavior of this function is undefined if the supplied tag is not a profile-specific |
| * or context-specific tag. |
| * |
| * @sa IsProfileTag() and IsContextTag() |
| * |
| * @param[in] tag The API representation of a profile-specific or context-specific TLV tag. |
| * @return The associated tag number. |
| */ |
| constexpr uint32_t TagNumFromTag(Tag tag) |
| { |
| return static_cast<uint32_t>(tag.mVal); |
| } |
| |
| /** |
| * Returns true of the supplied tag is a profile-specific tag. |
| */ |
| constexpr bool IsProfileTag(Tag tag) |
| { |
| return ProfileIdFromTag(tag) != Tag::kSpecialTagProfileId; |
| } |
| |
| /** |
| * Returns true if the supplied tag is a context-specific tag. |
| */ |
| constexpr bool IsContextTag(Tag tag) |
| { |
| return ProfileIdFromTag(tag) == Tag::kSpecialTagProfileId && TagNumFromTag(tag) <= Tag::kContextTagMaxNum; |
| } |
| |
| // TODO: move to private namespace |
| constexpr bool IsSpecialTag(Tag tag) |
| { |
| return ProfileIdFromTag(tag) == Tag::kSpecialTagProfileId; |
| } |
| |
| } // namespace TLV |
| } // namespace chip |