doublylinkedlist.c

00001 // Copyright (c) Microsoft. All rights reserved.
00002 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
00003 
00004 #include "azure_c_shared_utility/doublylinkedlist.h"
00005 
00006 void
00007 DList_InitializeListHead(
00008     PDLIST_ENTRY ListHead
00009 )
00010 {
00011     /* Codes_SRS_DLIST_06_005: [DList_InitializeListHead will initialize the Flink & Blink to the address of the DLIST_ENTRY.] */
00012     ListHead->Flink = ListHead->Blink = ListHead;
00013     return;
00014 }
00015 
00016 int
00017 DList_IsListEmpty(
00018     const PDLIST_ENTRY ListHead
00019 )
00020 {
00021     /* Codes_SRS_DLIST_06_003: [DList_IsListEmpty shall return a non-zero value if there are no DLIST_ENTRY's on this list other than the list head.] */
00022     /* Codes_SRS_DLIST_06_004: [DList_IsListEmpty shall return 0 if there is one or more items in the list.] */
00023     return (ListHead->Flink == ListHead);
00024 }
00025 
00026 int
00027 DList_RemoveEntryList(
00028     PDLIST_ENTRY Entry
00029 )
00030 {
00031     /* Codes_SRS_DLIST_06_008: [DList_RemoveEntryList shall remove a listEntry from whatever list it is properly part of.] */
00032     /* Codes_SRS_DLIST_06_009: [The remaining list is properly formed.] */
00033     /* Codes_SRS_DLIST_06_010: [DList_RemoveEntryList shall return non-zero if the remaining list is empty.] */
00034     /* Codes_SRS_DLIST_06_011: [DList_RemoveEntryList shall return zero if the remaining list is NOT empty.] */
00035     PDLIST_ENTRY Blink;
00036     PDLIST_ENTRY Flink;
00037 
00038     Flink = Entry->Flink;
00039     Blink = Entry->Blink;
00040     Blink->Flink = Flink;
00041     Flink->Blink = Blink;
00042     return (Flink == Blink);
00043 }
00044 
00045 PDLIST_ENTRY
00046 DList_RemoveHeadList(
00047     PDLIST_ENTRY ListHead
00048 )
00049 {
00050     /* Codes_SRS_DLIST_06_012: [DList_RemoveHeadList removes the oldest entry from the list defined by the listHead parameter and returns a pointer to that entry.] */
00051     /* Codes_SRS_DLIST_06_013: [DList_RemoveHeadList shall return listHead if that's the only item in the list.] */
00052 
00053     PDLIST_ENTRY Flink;
00054     PDLIST_ENTRY Entry;
00055 
00056     Entry = ListHead->Flink;
00057     Flink = Entry->Flink;
00058     ListHead->Flink = Flink;
00059     Flink->Blink = ListHead;
00060     return Entry;
00061 }
00062 
00063 
00064 
00065 void
00066 DList_InsertTailList(
00067     PDLIST_ENTRY ListHead,
00068     PDLIST_ENTRY Entry
00069 )
00070 {
00071     PDLIST_ENTRY Blink;
00072 
00073     /* Codes_SRS_DLIST_06_006: [DListInsertTailList shall place the DLIST_ENTRY at the end of the list defined by the listHead parameter.] */
00074     Blink = ListHead->Blink;
00075     Entry->Flink = ListHead;
00076     Entry->Blink = Blink;
00077     Blink->Flink = Entry;
00078     ListHead->Blink = Entry;
00079     return;
00080 }
00081 
00082 
00083 void
00084 DList_AppendTailList(
00085     PDLIST_ENTRY ListHead,
00086     PDLIST_ENTRY ListToAppend
00087 )
00088 {
00089     /* Codes_SRS_DLIST_06_007: [DList_AppendTailList shall place the list defined by listToAppend at the end of the list defined by the listHead parameter.] */
00090     PDLIST_ENTRY ListEnd = ListHead->Blink;
00091 
00092     ListHead->Blink->Flink = ListToAppend;
00093     ListHead->Blink = ListToAppend->Blink;
00094     ListToAppend->Blink->Flink = ListHead;
00095     ListToAppend->Blink = ListEnd;
00096     return;
00097 }
00098 
00099 
00100 /*Codes_SRS_DLIST_02_002: [DList_InsertHeadList inserts a singular entry in the list having as head listHead after "head".]*/
00101 void DList_InsertHeadList(PDLIST_ENTRY listHead, PDLIST_ENTRY entry)
00102 {
00103     entry->Blink = listHead;
00104     entry->Flink = listHead->Flink;
00105     listHead->Flink->Blink = entry;
00106     listHead->Flink = entry;
00107 }