| 1 | /** @file
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| 2 | An ordered collection library interface.
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| 3 |
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| 4 | The library class provides a set of APIs to manage an ordered collection of
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| 5 | items.
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| 6 |
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| 7 | Copyright (C) 2014, Red Hat, Inc.
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| 8 |
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| 9 | SPDX-License-Identifier: BSD-2-Clause-Patent
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| 10 | **/
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| 11 |
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| 12 | #ifndef __ORDERED_COLLECTION_LIB__
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| 13 | #define __ORDERED_COLLECTION_LIB__
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| 14 |
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| 15 | #include <Base.h>
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| 16 |
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| 17 | //
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| 18 | // Opaque structure for a collection.
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| 19 | //
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| 20 | typedef struct ORDERED_COLLECTION ORDERED_COLLECTION;
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| 21 |
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| 22 | //
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| 23 | // Opaque structure for collection entries.
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| 24 | //
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| 25 | // Collection entries do not take ownership of the associated user structures,
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| 26 | // they only link them. This makes it easy to link the same user structure into
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| 27 | // several collections. If reference counting is required, the caller is
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| 28 | // responsible for implementing it, as part of the user structure.
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| 29 | //
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| 30 | // A pointer-to-ORDERED_COLLECTION_ENTRY is considered an "iterator". Multiple,
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| 31 | // simultaneous iterations are supported.
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| 32 | //
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| 33 | typedef struct ORDERED_COLLECTION_ENTRY ORDERED_COLLECTION_ENTRY;
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| 34 |
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| 35 | //
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| 36 | // Altering the key field of an in-collection user structure (ie. the portion
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| 37 | // of the user structure that ORDERED_COLLECTION_USER_COMPARE and
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| 38 | // ORDERED_COLLECTION_KEY_COMPARE, below, read) is not allowed in-place. The
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| 39 | // caller is responsible for bracketing the key change with the deletion and
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| 40 | // the reinsertion of the user structure, so that the changed key value is
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| 41 | // reflected in the collection.
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| 42 | //
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| 43 |
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| 44 | /**
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| 45 | Comparator function type for two user structures.
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| 46 |
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| 47 | @param[in] UserStruct1 Pointer to the first user structure.
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| 48 |
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| 49 | @param[in] UserStruct2 Pointer to the second user structure.
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| 50 |
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| 51 | @retval <0 If UserStruct1 compares less than UserStruct2.
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| 52 |
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| 53 | @retval 0 If UserStruct1 compares equal to UserStruct2.
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| 54 |
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| 55 | @retval >0 If UserStruct1 compares greater than UserStruct2.
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| 56 | **/
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| 57 | typedef
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| 58 | INTN
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| 59 | (EFIAPI *ORDERED_COLLECTION_USER_COMPARE)(
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| 60 | IN CONST VOID *UserStruct1,
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| 61 | IN CONST VOID *UserStruct2
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| 62 | );
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| 63 |
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| 64 | /**
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| 65 | Compare a standalone key against a user structure containing an embedded key.
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| 66 |
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| 67 | @param[in] StandaloneKey Pointer to the bare key.
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| 68 |
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| 69 | @param[in] UserStruct Pointer to the user structure with the embedded
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| 70 | key.
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| 71 |
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| 72 | @retval <0 If StandaloneKey compares less than UserStruct's key.
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| 73 |
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| 74 | @retval 0 If StandaloneKey compares equal to UserStruct's key.
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| 75 |
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| 76 | @retval >0 If StandaloneKey compares greater than UserStruct's key.
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| 77 | **/
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| 78 | typedef
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| 79 | INTN
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| 80 | (EFIAPI *ORDERED_COLLECTION_KEY_COMPARE)(
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| 81 | IN CONST VOID *StandaloneKey,
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| 82 | IN CONST VOID *UserStruct
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| 83 | );
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| 84 |
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| 85 |
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| 86 | //
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| 87 | // Some functions below are read-only, while others are read-write. If any
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| 88 | // write operation is expected to run concurrently with any other operation on
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| 89 | // the same collection, then the caller is responsible for implementing locking
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| 90 | // for the whole collection.
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| 91 | //
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| 92 |
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| 93 | /**
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| 94 | Retrieve the user structure linked by the specified collection entry.
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| 95 |
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| 96 | Read-only operation.
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| 97 |
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| 98 | @param[in] Entry Pointer to the collection entry whose associated user
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| 99 | structure we want to retrieve. The caller is responsible
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| 100 | for passing a non-NULL argument.
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| 101 |
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| 102 | @return Pointer to user structure linked by Entry.
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| 103 | **/
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| 104 | VOID *
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| 105 | EFIAPI
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| 106 | OrderedCollectionUserStruct (
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| 107 | IN CONST ORDERED_COLLECTION_ENTRY *Entry
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| 108 | );
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| 109 |
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| 110 |
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| 111 | /**
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| 112 | Allocate and initialize the ORDERED_COLLECTION structure.
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| 113 |
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| 114 | @param[in] UserStructCompare This caller-provided function will be used to
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| 115 | order two user structures linked into the
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| 116 | collection, during the insertion procedure.
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| 117 |
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| 118 | @param[in] KeyCompare This caller-provided function will be used to
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| 119 | order the standalone search key against user
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| 120 | structures linked into the collection, during
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| 121 | the lookup procedure.
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| 122 |
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| 123 | @retval NULL If allocation failed.
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| 124 |
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| 125 | @return Pointer to the allocated, initialized ORDERED_COLLECTION
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| 126 | structure, otherwise.
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| 127 | **/
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| 128 | ORDERED_COLLECTION *
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| 129 | EFIAPI
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| 130 | OrderedCollectionInit (
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| 131 | IN ORDERED_COLLECTION_USER_COMPARE UserStructCompare,
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| 132 | IN ORDERED_COLLECTION_KEY_COMPARE KeyCompare
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| 133 | );
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| 134 |
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| 135 |
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| 136 | /**
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| 137 | Check whether the collection is empty (has no entries).
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| 138 |
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| 139 | Read-only operation.
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| 140 |
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| 141 | @param[in] Collection The collection to check for emptiness.
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| 142 |
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| 143 | @retval TRUE The collection is empty.
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| 144 |
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| 145 | @retval FALSE The collection is not empty.
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| 146 | **/
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| 147 | BOOLEAN
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| 148 | EFIAPI
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| 149 | OrderedCollectionIsEmpty (
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| 150 | IN CONST ORDERED_COLLECTION *Collection
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| 151 | );
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| 152 |
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| 153 |
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| 154 | /**
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| 155 | Uninitialize and release an empty ORDERED_COLLECTION structure.
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| 156 |
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| 157 | Read-write operation.
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| 158 |
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| 159 | It is the caller's responsibility to delete all entries from the collection
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| 160 | before calling this function.
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| 161 |
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| 162 | @param[in] Collection The empty collection to uninitialize and release.
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| 163 | **/
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| 164 | VOID
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| 165 | EFIAPI
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| 166 | OrderedCollectionUninit (
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| 167 | IN ORDERED_COLLECTION *Collection
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| 168 | );
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| 169 |
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| 170 |
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| 171 | /**
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| 172 | Look up the collection entry that links the user structure that matches the
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| 173 | specified standalone key.
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| 174 |
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| 175 | Read-only operation.
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| 176 |
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| 177 | @param[in] Collection The collection to search for StandaloneKey.
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| 178 |
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| 179 | @param[in] StandaloneKey The key to locate among the user structures linked
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| 180 | into Collection. StandaloneKey will be passed to
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| 181 | ORDERED_COLLECTION_KEY_COMPARE.
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| 182 |
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| 183 | @retval NULL StandaloneKey could not be found.
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| 184 |
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| 185 | @return The collection entry that links to the user structure matching
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| 186 | StandaloneKey, otherwise.
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| 187 | **/
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| 188 | ORDERED_COLLECTION_ENTRY *
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| 189 | EFIAPI
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| 190 | OrderedCollectionFind (
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| 191 | IN CONST ORDERED_COLLECTION *Collection,
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| 192 | IN CONST VOID *StandaloneKey
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| 193 | );
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| 194 |
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| 195 |
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| 196 | /**
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| 197 | Find the collection entry of the minimum user structure stored in the
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| 198 | collection.
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| 199 |
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| 200 | Read-only operation.
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| 201 |
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| 202 | @param[in] Collection The collection to return the minimum entry of. The
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| 203 | user structure linked by the minimum entry compares
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| 204 | less than all other user structures in the collection.
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| 205 |
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| 206 | @retval NULL If Collection is empty.
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| 207 |
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| 208 | @return The collection entry that links the minimum user structure,
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| 209 | otherwise.
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| 210 | **/
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| 211 | ORDERED_COLLECTION_ENTRY *
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| 212 | EFIAPI
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| 213 | OrderedCollectionMin (
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| 214 | IN CONST ORDERED_COLLECTION *Collection
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| 215 | );
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| 216 |
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| 217 |
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| 218 | /**
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| 219 | Find the collection entry of the maximum user structure stored in the
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| 220 | collection.
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| 221 |
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| 222 | Read-only operation.
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| 223 |
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| 224 | @param[in] Collection The collection to return the maximum entry of. The
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| 225 | user structure linked by the maximum entry compares
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| 226 | greater than all other user structures in the
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| 227 | collection.
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| 228 |
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| 229 | @retval NULL If Collection is empty.
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| 230 |
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| 231 | @return The collection entry that links the maximum user structure,
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| 232 | otherwise.
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| 233 | **/
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| 234 | ORDERED_COLLECTION_ENTRY *
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| 235 | EFIAPI
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| 236 | OrderedCollectionMax (
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| 237 | IN CONST ORDERED_COLLECTION *Collection
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| 238 | );
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| 239 |
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| 240 |
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| 241 | /**
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| 242 | Get the collection entry of the least user structure that is greater than the
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| 243 | one linked by Entry.
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| 244 |
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| 245 | Read-only operation.
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| 246 |
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| 247 | @param[in] Entry The entry to get the successor entry of.
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| 248 |
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| 249 | @retval NULL If Entry is NULL, or Entry is the maximum entry of its
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| 250 | containing collection (ie. Entry has no successor entry).
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| 251 |
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| 252 | @return The collection entry linking the least user structure that is
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| 253 | greater than the one linked by Entry, otherwise.
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| 254 | **/
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| 255 | ORDERED_COLLECTION_ENTRY *
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| 256 | EFIAPI
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| 257 | OrderedCollectionNext (
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| 258 | IN CONST ORDERED_COLLECTION_ENTRY *Entry
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| 259 | );
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| 260 |
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| 261 |
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| 262 | /**
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| 263 | Get the collection entry of the greatest user structure that is less than the
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| 264 | one linked by Entry.
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| 265 |
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| 266 | Read-only operation.
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| 267 |
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| 268 | @param[in] Entry The entry to get the predecessor entry of.
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| 269 |
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| 270 | @retval NULL If Entry is NULL, or Entry is the minimum entry of its
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| 271 | containing collection (ie. Entry has no predecessor entry).
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| 272 |
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| 273 | @return The collection entry linking the greatest user structure that
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| 274 | is less than the one linked by Entry, otherwise.
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| 275 | **/
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| 276 | ORDERED_COLLECTION_ENTRY *
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| 277 | EFIAPI
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| 278 | OrderedCollectionPrev (
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| 279 | IN CONST ORDERED_COLLECTION_ENTRY *Entry
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| 280 | );
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| 281 |
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| 282 |
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| 283 | /**
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| 284 | Insert (link) a user structure into the collection, allocating a new
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| 285 | collection entry.
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| 286 |
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| 287 | Read-write operation.
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| 288 |
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| 289 | @param[in,out] Collection The collection to insert UserStruct into.
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| 290 |
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| 291 | @param[out] Entry The meaning of this optional, output-only
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| 292 | parameter depends on the return value of the
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| 293 | function.
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| 294 |
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| 295 | When insertion is successful (RETURN_SUCCESS),
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| 296 | Entry is set on output to the new collection entry
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| 297 | that now links UserStruct.
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| 298 |
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| 299 | When insertion fails due to lack of memory
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| 300 | (RETURN_OUT_OF_RESOURCES), Entry is not changed.
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| 301 |
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| 302 | When insertion fails due to key collision (ie.
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| 303 | another user structure is already in the
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| 304 | collection that compares equal to UserStruct),
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| 305 | with return value RETURN_ALREADY_STARTED, then
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| 306 | Entry is set on output to the entry that links the
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| 307 | colliding user structure. This enables
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| 308 | "find-or-insert" in one function call, or helps
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| 309 | with later removal of the colliding element.
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| 310 |
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| 311 | @param[in] UserStruct The user structure to link into the collection.
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| 312 | UserStruct is ordered against in-collection user
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| 313 | structures with the
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| 314 | ORDERED_COLLECTION_USER_COMPARE function.
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| 315 |
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| 316 | @retval RETURN_SUCCESS Insertion successful. A new collection entry
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| 317 | has been allocated, linking UserStruct. The
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| 318 | new collection entry is reported back in
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| 319 | Entry (if the caller requested it).
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| 320 |
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| 321 | Existing ORDERED_COLLECTION_ENTRY pointers
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| 322 | into Collection remain valid. For example,
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| 323 | on-going iterations in the caller can
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| 324 | continue with OrderedCollectionNext() /
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| 325 | OrderedCollectionPrev(), and they will
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| 326 | return the new entry at some point if user
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| 327 | structure order dictates it.
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| 328 |
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| 329 | @retval RETURN_OUT_OF_RESOURCES The function failed to allocate memory for
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| 330 | the new collection entry. The collection has
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| 331 | not been changed. Existing
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| 332 | ORDERED_COLLECTION_ENTRY pointers into
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| 333 | Collection remain valid.
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| 334 |
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| 335 | @retval RETURN_ALREADY_STARTED A user structure has been found in the
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| 336 | collection that compares equal to
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| 337 | UserStruct. The entry linking the colliding
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| 338 | user structure is reported back in Entry (if
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| 339 | the caller requested it). The collection has
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| 340 | not been changed. Existing
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| 341 | ORDERED_COLLECTION_ENTRY pointers into
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| 342 | Collection remain valid.
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| 343 | **/
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| 344 | RETURN_STATUS
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| 345 | EFIAPI
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| 346 | OrderedCollectionInsert (
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| 347 | IN OUT ORDERED_COLLECTION *Collection,
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| 348 | OUT ORDERED_COLLECTION_ENTRY **Entry OPTIONAL,
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| 349 | IN VOID *UserStruct
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| 350 | );
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| 351 |
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| 352 |
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| 353 | /**
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| 354 | Delete an entry from the collection, unlinking the associated user structure.
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| 355 |
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| 356 | Read-write operation.
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| 357 |
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| 358 | @param[in,out] Collection The collection to delete Entry from.
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| 359 |
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| 360 | @param[in] Entry The collection entry to delete from Collection.
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| 361 | The caller is responsible for ensuring that Entry
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| 362 | belongs to Collection, and that Entry is non-NULL
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| 363 | and valid. Entry is typically an earlier return
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| 364 | value, or output parameter, of:
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| 365 |
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| 366 | - OrderedCollectionFind(), for deleting an entry
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| 367 | by user structure key,
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| 368 |
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| 369 | - OrderedCollectionMin() / OrderedCollectionMax(),
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| 370 | for deleting the minimum / maximum entry,
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| 371 |
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| 372 | - OrderedCollectionNext() /
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| 373 | OrderedCollectionPrev(), for deleting an entry
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| 374 | found during an iteration,
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| 375 |
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| 376 | - OrderedCollectionInsert() with return value
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| 377 | RETURN_ALREADY_STARTED, for deleting an entry
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| 378 | whose linked user structure caused collision
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| 379 | during insertion.
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| 380 |
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| 381 | Existing ORDERED_COLLECTION_ENTRY pointers (ie.
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| 382 | iterators) *different* from Entry remain valid.
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| 383 | For example:
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| 384 |
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| 385 | - OrderedCollectionNext() /
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| 386 | OrderedCollectionPrev() iterations in the caller
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| 387 | can be continued from Entry, if
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| 388 | OrderedCollectionNext() or
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| 389 | OrderedCollectionPrev() is called on Entry
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| 390 | *before* OrderedCollectionDelete() is. That is,
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| 391 | fetch the successor / predecessor entry first,
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| 392 | then delete Entry.
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| 393 |
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| 394 | - On-going iterations in the caller that would
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| 395 | have otherwise returned Entry at some point, as
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| 396 | dictated by user structure order, will correctly
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| 397 | reflect the absence of Entry after
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| 398 | OrderedCollectionDelete() is called
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| 399 | mid-iteration.
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| 400 |
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| 401 | @param[out] UserStruct If the caller provides this optional output-only
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| 402 | parameter, then on output it is set to the user
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| 403 | structure originally linked by Entry (which is now
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| 404 | freed).
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| 405 |
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| 406 | This is a convenience that may save the caller a
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| 407 | OrderedCollectionUserStruct() invocation before
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| 408 | calling OrderedCollectionDelete(), in order to
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| 409 | retrieve the user structure being unlinked.
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| 410 | **/
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| 411 | VOID
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| 412 | EFIAPI
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| 413 | OrderedCollectionDelete (
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| 414 | IN OUT ORDERED_COLLECTION *Collection,
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| 415 | IN ORDERED_COLLECTION_ENTRY *Entry,
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| 416 | OUT VOID **UserStruct OPTIONAL
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| 417 | );
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| 418 |
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| 419 | #endif
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