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308 lines
10 KiB
308 lines
10 KiB
/**
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@file
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@ingroup util
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@brief Ancient implementation of qsort.
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@details This is shipped with CUDD so that results of reordering may
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be more reproducible across different platforms.
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qsort.c 4.2 (Berkeley) 3/9/83
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Our own version of the system qsort routine which is faster by an average
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of 25%, with lows and highs of 10% and 50%.
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The THRESHold below is the insertion sort threshold, and has been adjusted
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for records of size 48 bytes.
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The MTHREShold is where we stop finding a better median.
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@copyright@parblock
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Copyright (c) 1994-1998 The Regents of the Univ. of California.
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All rights reserved.
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Permission is hereby granted, without written agreement and without license
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or royalty fees, to use, copy, modify, and distribute this software and its
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documentation for any purpose, provided that the above copyright notice and
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the following two paragraphs appear in all copies of this software.
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IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
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DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
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OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
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CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
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INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN
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"AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO PROVIDE
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MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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@endparblock
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@copyright@parblock
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Copyright (c) 1999-2015, Regents of the University of Colorado
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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:
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Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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Neither the name of the University of Colorado nor the names of its
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contributors may be used to endorse or promote products derived from
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this software without specific prior written 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 THE
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COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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@endparblock
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*/
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#include "util.h"
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#ifndef USE_SYSTEM_QSORT
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/**
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@brief Threshold for insertion.
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*/
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#define THRESH 4
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/**
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@brief Threshold for median.
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*/
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#define MTHRESH 6
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/**
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@brief Miscellaneous information.
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*/
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typedef struct {
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QSFP qcmp; /**< the comparison routine */
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int qsz; /**< size of each record */
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int thresh; /**< THRESHold in chars */
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int mthresh; /**< MTHRESHold in chars */
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} info_t;
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/*---------------------------------------------------------------------------*/
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/* Static function prototypes */
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/*---------------------------------------------------------------------------*/
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/** \cond */
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static void qst (char *base, char *max, info_t const * info);
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/** \endcond */
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/*---------------------------------------------------------------------------*/
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/* Definition of exported functions */
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/*---------------------------------------------------------------------------*/
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#undef min
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#undef max
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#endif
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/**
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* @brief Implements the quicksort algorithm.
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*
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* @details First, set up some global parameters for qst to share.
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* Then, quicksort with qst(), and then a cleanup insertion sort
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* ourselves. Sound simple? It's not...
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*/
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void
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util_qsort(
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void *vbase /**< start address of array */,
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int n /**< number of items */,
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int size /**< size of each item */,
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QSFP compar /**< comparison function */)
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{
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#ifdef USE_SYSTEM_QSORT
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qsort(vbase, n, size, compar);
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#else
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char *base = (char *) vbase;
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char c, *i, *j, *lo, *hi;
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char *min, *max;
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info_t info;
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if (n <= 1)
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return;
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info.qsz = size;
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info.qcmp = compar;
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info.thresh = size * THRESH;
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info.mthresh = size * MTHRESH;
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max = base + n * size;
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if (n >= THRESH) {
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qst(base, max, &info);
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hi = base + info.thresh;
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} else {
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hi = max;
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}
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/*
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* First put smallest element, which must be in the first THRESH, in
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* the first position as a sentinel. This is done just by searching
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* the first THRESH elements (or the first n if n < THRESH), finding
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* the min, and swapping it into the first position.
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*/
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for (j = lo = base; (lo += size) < hi; )
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if ((*compar)(j, lo) > 0)
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j = lo;
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if (j != base) {
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/* swap j into place */
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for (i = base, hi = base + size; i < hi; ) {
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c = *j;
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*j++ = *i;
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*i++ = c;
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}
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}
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/*
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* With our sentinel in place, we now run the following hyper-fast
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* insertion sort. For each remaining element, min, from [1] to [n-1],
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* set hi to the index of the element AFTER which this one goes.
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* Then, do the standard insertion sort shift on a character at a time
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* basis for each element in the frob.
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*/
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for (min = base; (hi = min += size) < max; ) {
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while ((*compar)(hi -= size, min) > 0)
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/* void */;
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if ((hi += size) != min) {
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for (lo = min + size; --lo >= min; ) {
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c = *lo;
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for (i = j = lo; (j -= size) >= hi; i = j)
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*i = *j;
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*i = c;
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}
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}
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}
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#endif
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}
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/*---------------------------------------------------------------------------*/
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/* Definition of static functions */
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/*---------------------------------------------------------------------------*/
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/**
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* @brief Do a quicksort.
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*
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* @details First, find the median element, and put that one in the
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* first place as the discriminator. (This "median" is just the
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* median of the first, last and middle elements). (Using this median
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* instead of the first element is a big win). Then, the usual
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* partitioning/swapping, followed by moving the discriminator into
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* the right place. Then, figure out the sizes of the two partions,
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* do the smaller one recursively and the larger one via a repeat of
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* this code. Stopping when there are less than THRESH elements in a
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* partition and cleaning up with an insertion sort (in our caller) is
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* a huge win. All data swaps are done in-line, which is space-losing
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* but time-saving. (And there are only three places where this is
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* done).
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*/
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#ifndef USE_SYSTEM_QSORT
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static void
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qst(char *base, char *max, info_t const * info)
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{
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char c, *i, *j, *jj;
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int ii;
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char *mid, *tmp;
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intptr_t lo, hi;
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/*
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* At the top here, lo is the number of characters of elements in the
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* current partition. (Which should be max - base).
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* Find the median of the first, last, and middle element and make
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* that the middle element. Set j to largest of first and middle.
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* If max is larger than that guy, then it's that guy, else compare
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* max with loser of first and take larger. Things are set up to
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* prefer the middle, then the first in case of ties.
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*/
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lo = max - base; /* number of elements as chars */
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do {
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mid = i = base + info->qsz * ((lo / info->qsz) >> 1);
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if (lo >= info->mthresh) {
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j = ((*info->qcmp)((jj = base), i) > 0 ? jj : i);
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if ((*info->qcmp)(j, (tmp = max - info->qsz)) > 0) {
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/* switch to first loser */
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j = (j == jj ? i : jj);
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if ((*info->qcmp)(j, tmp) < 0)
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j = tmp;
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}
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if (j != i) {
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ii = info->qsz;
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do {
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c = *i;
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*i++ = *j;
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*j++ = c;
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} while (--ii);
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}
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}
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/*
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* Semi-standard quicksort partitioning/swapping
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*/
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for (i = base, j = max - info->qsz; ; ) {
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while (i < mid && (*info->qcmp)(i, mid) <= 0)
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i += info->qsz;
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while (j > mid) {
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if ((*info->qcmp)(mid, j) <= 0) {
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j -= info->qsz;
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continue;
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}
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tmp = i + info->qsz; /* value of i after swap */
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if (i == mid) {
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/* j <-> mid, new mid is j */
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mid = jj = j;
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} else {
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/* i <-> j */
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jj = j;
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j -= info->qsz;
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}
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goto swap;
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}
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if (i == mid) {
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break;
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} else {
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/* i <-> mid, new mid is i */
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jj = mid;
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tmp = mid = i; /* value of i after swap */
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j -= info->qsz;
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}
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swap:
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ii = info->qsz;
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do {
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c = *i;
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*i++ = *jj;
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*jj++ = c;
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} while (--ii);
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i = tmp;
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}
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/*
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* Look at sizes of the two partitions, do the smaller
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* one first by recursion, then do the larger one by
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* making sure lo is its size, base and max are update
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* correctly, and branching back. But only repeat
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* (recursively or by branching) if the partition is
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* of at least size THRESH.
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*/
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i = (j = mid) + info->qsz;
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if ((lo = j - base) <= (hi = max - i)) {
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if (lo >= info->thresh)
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qst(base, j, info);
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base = i;
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lo = hi;
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} else {
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if (hi >= info->thresh)
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qst(i, max, info);
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max = j;
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}
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} while (lo >= info->thresh);
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}
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#endif
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