3c99391d93
In some cases the license-identification header was missing, so I added that as well. Replaced the remaining headers that specifically identified "Versions 3.13.7 and higher". Makefiles and the build system were deliberately excluded.
84 lines
2.2 KiB
C
84 lines
2.2 KiB
C
/*************************************************************************\
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* Copyright (c) 2014 Brookhaven Science Assoc., as Operator of Argonne
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* National Laboratory.
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* Copyright (c) 2016 Michael Davidsaver
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* SPDX-License-Identifier: EPICS
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* EPICS BASE is distributed subject to a Software License Agreement found
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* in file LICENSE that is included with this distribution.
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\*************************************************************************/
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/*
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* Use of mergesort algorithm based on analysis by
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* http://www.chiark.greenend.org.uk/~sgtatham/algorithms/listsort.html
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*/
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#include <stdlib.h>
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#include "epicsAssert.h"
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#include "ellLib.h"
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static void ellMoveN(ELLLIST* pTo, ELLLIST* pFrom, int count )
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{
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for(;count && ellCount(pFrom); count--) {
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ELLNODE *node = ellGet(pFrom);
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ellAdd(pTo, node);
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}
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}
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/* Stable (MergeSort) to given list.
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* The comparison function cmp(A,B) is expected
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* to return -1 for A<B, 0 for A==B, and 1 for A>B.
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*/
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void ellSortStable(ELLLIST *pList, pListCmp cmp)
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{
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ELLLIST INP, P, Q;
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size_t insize = 1; /* initial sub-list size */
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if(ellCount(pList)<=1)
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return;
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ellInit(&INP);
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ellInit(&P);
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ellInit(&Q);
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/* Process is to iteratively sort
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* a sequence of sub-lists of size 'insize'
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*/
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while(insize < ellCount(pList)) {
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assert(ellCount(&INP)==0);
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/* shift previous results to inputs */
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ellConcat(&INP, pList);
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while(ellCount(&INP))
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{
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ELLNODE *p, *q;
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/* Pull out the next pair of sub-lists */
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ellMoveN(&Q, &INP, insize);
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ellMoveN(&P, &INP, insize);
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/* merge these sub-lists */
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while((p=ellFirst(&P)) && (q=ellFirst(&Q)))
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{
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if((*cmp)(p,q) < 0) {
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ellAdd(pList, ellGet(&P));
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} else {
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ellAdd(pList, ellGet(&Q));
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}
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}
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/* concatenate any remaining to result */
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if(ellFirst(&P))
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ellConcat(pList, &P);
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else if(ellFirst(&Q))
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ellConcat(pList, &Q);
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assert(!ellFirst(&P) && !ellFirst(&Q));
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}
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insize *= 2;
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}
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}
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