142 lines
4.0 KiB
C
142 lines
4.0 KiB
C
/*
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Copyright (c) 2014 Anton Titov.
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Copyright (c) 2014 pCloud Ltd. All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met: Redistributions of source code must retain the above
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copyright notice, this list of conditions and the following
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disclaimer. Redistributions in binary form must reproduce the
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above copyright notice, this list of conditions and the following
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disclaimer in the documentation and/or other materials provided
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with the distribution. Neither the name of pCloud Ltd nor the
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names of its contributors may be used to endorse or promote
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products derived from this software without specific prior written
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permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL pCloud
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Ltd BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
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USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
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DAMAGE.
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*/
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#include "plist.h"
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#include "pfile.h"
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/* Fairly simple in-place merge sort with constant storage requirements.
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*
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* Recursive approach might would use O(log N) storage on the stack but may
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* have better cache locality for lists that do not fit in processor cache,
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* may benefit from precise in-half splitting and can go without needless
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* iterating of the list to reach the half of it.
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*/
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void psync_list_sort(psync_list *l, psync_list_compare cmp) {
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psync_list *ls, *l1, *l2, **tail;
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unsigned long depth, cnt, i, l1len, l2len;
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if (psync_list_isempty(l))
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return;
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ls = l->next;
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l->prev->next = NULL;
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depth = 1;
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while (1) {
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l1 = ls;
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tail = &ls;
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cnt = 0;
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while (l1) {
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cnt++;
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l2 = l1;
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for (i = 0; i < depth && l2; i++)
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l2 = l2->next;
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if (!l2) {
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*tail = l1;
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goto nol2;
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}
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l1len = i;
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l2len = depth;
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while (1) {
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if (cmp(l1, l2) <= 0) {
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l1len--;
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*tail = l1;
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tail = &l1->next;
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if (!l1len)
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goto l1fin;
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l1 = l1->next;
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} else {
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l2len--;
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*tail = l2;
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tail = &l2->next;
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l2 = l2->next;
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if (!l2len || !l2)
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goto l2fin;
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}
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}
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l2fin:
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*tail = l1;
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for (i = 0; i < l1len - 1; i++)
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l1 = l1->next;
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tail = &l1->next;
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l1 = l2;
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continue;
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l1fin:
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*tail = l2;
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for (i = 0; l2->next && i < l2len - 1; i++)
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l2 = l2->next;
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tail = &l2->next;
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l1 = l2->next;
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}
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*tail = NULL;
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nol2:
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if (cnt <= 1)
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break;
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depth *= 2;
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}
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l->next = ls;
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l1 = l;
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while (ls) {
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ls->prev = l1;
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l1 = ls;
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ls = ls->next;
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}
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l1->next = l;
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l->prev = l1;
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}
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void psync_list_extract_repeating(psync_list *l1, psync_list *l2,
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psync_list *extracted1,
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psync_list *extracted2,
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psync_list_compare cmp) {
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psync_list *li1, *li2, *ln1, *ln2;
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int cr;
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psync_list_sort(l1, cmp);
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psync_list_sort(l2, cmp);
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li1 = l1->next;
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li2 = l2->next;
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while (li1 != l1 && li2 != l2) {
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cr = cmp(li1, li2);
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if (cr < 0)
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li1 = li1->next;
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else if (cr > 0)
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li2 = li2->next;
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else {
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ln1 = li1->next;
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ln2 = li2->next;
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psync_list_del(li1);
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psync_list_add_tail(extracted1, li1);
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psync_list_del(li2);
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psync_list_add_tail(extracted2, li2);
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li1 = ln1;
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li2 = ln2;
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}
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}
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}
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