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