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      1 // Copyright (c) 2008, Google Inc.
      2 // All rights reserved.
      3 //
      4 // Redistribution and use in source and binary forms, with or without
      5 // modification, are permitted provided that the following conditions are
      6 // met:
      7 //
      8 //     * Redistributions of source code must retain the above copyright
      9 // notice, this list of conditions and the following disclaimer.
     10 //     * Redistributions in binary form must reproduce the above
     11 // copyright notice, this list of conditions and the following disclaimer
     12 // in the documentation and/or other materials provided with the
     13 // distribution.
     14 //     * Neither the name of Google Inc. nor the names of its
     15 // contributors may be used to endorse or promote products derived from
     16 // this software without specific prior written permission.
     17 //
     18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29 
     30 // ---
     31 // Author: Sanjay Ghemawat <opensource (at) google.com>
     32 //
     33 // Some very basic linked list functions for dealing with using void * as
     34 // storage.
     35 
     36 #ifndef TCMALLOC_LINKED_LIST_H_
     37 #define TCMALLOC_LINKED_LIST_H_
     38 
     39 #include <stddef.h>
     40 
     41 namespace tcmalloc {
     42 
     43 inline void *SLL_Next(void *t) {
     44   return *(reinterpret_cast<void**>(t));
     45 }
     46 
     47 inline void SLL_SetNext(void *t, void *n) {
     48   *(reinterpret_cast<void**>(t)) = n;
     49 }
     50 
     51 inline void SLL_Push(void **list, void *element) {
     52   SLL_SetNext(element, *list);
     53   *list = element;
     54 }
     55 
     56 inline void *SLL_Pop(void **list) {
     57   void *result = *list;
     58   *list = SLL_Next(*list);
     59   return result;
     60 }
     61 
     62 // Remove N elements from a linked list to which head points.  head will be
     63 // modified to point to the new head.  start and end will point to the first
     64 // and last nodes of the range.  Note that end will point to NULL after this
     65 // function is called.
     66 inline void SLL_PopRange(void **head, int N, void **start, void **end) {
     67   if (N == 0) {
     68     *start = NULL;
     69     *end = NULL;
     70     return;
     71   }
     72 
     73   void *tmp = *head;
     74   for (int i = 1; i < N; ++i) {
     75     tmp = SLL_Next(tmp);
     76   }
     77 
     78   *start = *head;
     79   *end = tmp;
     80   *head = SLL_Next(tmp);
     81   // Unlink range from list.
     82   SLL_SetNext(tmp, NULL);
     83 }
     84 
     85 inline void SLL_PushRange(void **head, void *start, void *end) {
     86   if (!start) return;
     87   SLL_SetNext(end, *head);
     88   *head = start;
     89 }
     90 
     91 inline size_t SLL_Size(void *head) {
     92   int count = 0;
     93   while (head) {
     94     count++;
     95     head = SLL_Next(head);
     96   }
     97   return count;
     98 }
     99 
    100 }  // namespace tcmalloc
    101 
    102 #endif  // TCMALLOC_LINKED_LIST_H_
    103