+++ /dev/null
-/* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */
-
-#include <stdlib.h>
-#include <search.h>
-
-/*-
- * Copyright (c) 1980, 1983 The Regents of the University of California.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms are permitted
- * provided that: (1) source distributions retain this entire copyright
- * notice and comment, and (2) distributions including binaries display
- * the following acknowledgement: ``This product includes software
- * developed by the University of California, Berkeley and its contributors''
- * in the documentation or other materials provided with the distribution
- * and in all advertising materials mentioning features or use of this
- * software. Neither the name of the University 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR
- * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
- */
-
-/*
- * qsort.c:
- * 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.
- */
-
-#define THRESH 4 /* threshold for insertion */
-#define MTHRESH 6 /* threshold for median */
-
-/*
- * qst:
- * Do a quicksort
- * 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).
- */
-
-static void __cdecl
-qst(size_t size, int (__cdecl *compar)(const void*, const void*), char *base, char *max)
-{
- char c, *i, *j, *jj;
- size_t ii;
- char *mid, *tmp;
- size_t lo, hi;
- size_t thresh;
- size_t mthresh;
-
- thresh = size * THRESH;
- mthresh = size * MTHRESH;
-
- /*
- * 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 + size * ((lo / size) >> 1);
- if (lo >= mthresh)
- {
- j = (compar((jj = base), i) > 0 ? jj : i);
- if (compar(j, (tmp = max - size)) > 0)
- {
- /* switch to first loser */
- j = (j == jj ? i : jj);
- if (compar(j, tmp) < 0)
- j = tmp;
- }
- if (j != i)
- {
- ii = size;
- do {
- c = *i;
- *i++ = *j;
- *j++ = c;
- } while (--ii);
- }
- }
- /*
- * Semi-standard quicksort partitioning/swapping
- */
- for (i = base, j = max - size; ; )
- {
- while (i < mid && compar(i, mid) <= 0)
- i += size;
- while (j > mid)
- {
- if (compar(mid, j) <= 0)
- {
- j -= size;
- continue;
- }
- tmp = i + size; /* value of i after swap */
- if (i == mid)
- {
- /* j <-> mid, new mid is j */
- mid = jj = j;
- }
- else
- {
- /* i <-> j */
- jj = j;
- j -= size;
- }
- goto swap;
- }
- if (i == mid)
- {
- break;
- }
- else
- {
- /* i <-> mid, new mid is i */
- jj = mid;
- tmp = mid = i; /* value of i after swap */
- j -= size;
- }
- swap:
- ii = size;
- 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) + size;
- if ((lo = j - base) <= (hi = max - i))
- {
- if (lo >= thresh)
- qst(size, compar, base, j);
- base = i;
- lo = hi;
- }
- else
- {
- if (hi >= thresh)
- qst(size, compar, i, max);
- max = j;
- }
- } while (lo >= thresh);
-}
-
-/*
- * qsort:
- * 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...
- *
- * @implemented
- */
-void
-__cdecl
-qsort(void *base0, size_t n, size_t size, int (__cdecl *compar)(const void*, const void*))
-{
- char *base = (char *)base0;
- char c, *i, *j, *lo, *hi;
- char *min, *max;
- size_t thresh;
-
- if (n <= 1)
- return;
-
- if (size == 0)
- return;
- compar = compar;
- thresh = size * THRESH;
- max = base + n * size;
- if (n >= THRESH)
- {
- qst(size, compar, base, max);
- hi = base + 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;
- }
- }
- }
-}
projects / reactos.git / blobdiff