| /* |
| * qsort.c: standard quicksort algorithm |
| * |
| * Modifications from vanilla NetBSD source: |
| * Add do ... while() macro fix |
| * Remove __inline, _DIAGASSERTs, __P |
| * Remove ill-considered "swap_cnt" switch to insertion sort, |
| * in favor of a simple check for presorted input. |
| * |
| * CAUTION: if you change this file, see also qsort_arg.c |
| * |
| * $PostgreSQL: pgsql/src/port/qsort.c,v 1.13 2007/03/18 05:36:50 neilc Exp $ |
| */ |
| |
| /* $NetBSD: qsort.c,v 1.13 2003/08/07 16:43:42 agc Exp $ */ |
| |
| /*- |
| * Copyright (c) 1992, 1993 |
| * The Regents of the University of California. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. 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. |
| * 3. 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 BY THE REGENTS 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 REGENTS 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; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| */ |
| |
| #include "c.h" |
| |
| |
| static char *med3(char *a, char *b, char *c, |
| int (*cmp) (const void *, const void *)); |
| static void swapfunc(char *, char *, size_t, int); |
| |
| /* |
| * Qsort routine based on J. L. Bentley and M. D. McIlroy, |
| * "Engineering a sort function", |
| * Software--Practice and Experience 23 (1993) 1249-1265. |
| * We have modified their original by adding a check for already-sorted input, |
| * which seems to be a win per discussions on pgsql-hackers around 2006-03-21. |
| */ |
| #define swapcode(TYPE, parmi, parmj, n) \ |
| do { \ |
| size_t i = (n) / sizeof (TYPE); \ |
| TYPE *pi = (TYPE *)(void *)(parmi); \ |
| TYPE *pj = (TYPE *)(void *)(parmj); \ |
| do { \ |
| TYPE t = *pi; \ |
| *pi++ = *pj; \ |
| *pj++ = t; \ |
| } while (--i > 0); \ |
| } while (0) |
| |
| #define SWAPINIT(a, es) swaptype = ((char *)(a) - (char *)0) % sizeof(long) || \ |
| (es) % sizeof(long) ? 2 : (es) == sizeof(long)? 0 : 1; |
| |
| static void |
| swapfunc(char *a, char *b, size_t n, int swaptype) |
| { |
| if (swaptype <= 1) |
| swapcode(long, a, b, n); |
| else |
| swapcode(char, a, b, n); |
| } |
| |
| #define swap(a, b) \ |
| if (swaptype == 0) { \ |
| long t = *(long *)(void *)(a); \ |
| *(long *)(void *)(a) = *(long *)(void *)(b); \ |
| *(long *)(void *)(b) = t; \ |
| } else \ |
| swapfunc(a, b, es, swaptype) |
| |
| #define vecswap(a, b, n) if ((n) > 0) swapfunc((a), (b), (size_t)(n), swaptype) |
| |
| static char * |
| med3(char *a, char *b, char *c, int (*cmp) (const void *, const void *)) |
| { |
| return cmp(a, b) < 0 ? |
| (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a)) |
| : (cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c)); |
| } |
| |
| void |
| pg_qsort(void *a, size_t n, size_t es, int (*cmp) (const void *, const void *)) |
| { |
| char *pa, |
| *pb, |
| *pc, |
| *pd, |
| *pl, |
| *pm, |
| *pn; |
| int d, |
| r, |
| swaptype, |
| presorted; |
| |
| loop:SWAPINIT(a, es); |
| if (n < 7) |
| { |
| for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) |
| for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; |
| pl -= es) |
| swap(pl, pl - es); |
| return; |
| } |
| presorted = 1; |
| for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) |
| { |
| if (cmp(pm - es, pm) > 0) |
| { |
| presorted = 0; |
| break; |
| } |
| } |
| if (presorted) |
| return; |
| pm = (char *) a + (n / 2) * es; |
| if (n > 7) |
| { |
| pl = (char *) a; |
| pn = (char *) a + (n - 1) * es; |
| if (n > 40) |
| { |
| d = (n / 8) * es; |
| pl = med3(pl, pl + d, pl + 2 * d, cmp); |
| pm = med3(pm - d, pm, pm + d, cmp); |
| pn = med3(pn - 2 * d, pn - d, pn, cmp); |
| } |
| pm = med3(pl, pm, pn, cmp); |
| } |
| swap(a, pm); |
| pa = pb = (char *) a + es; |
| pc = pd = (char *) a + (n - 1) * es; |
| for (;;) |
| { |
| while (pb <= pc && (r = cmp(pb, a)) <= 0) |
| { |
| if (r == 0) |
| { |
| swap(pa, pb); |
| pa += es; |
| } |
| pb += es; |
| } |
| while (pb <= pc && (r = cmp(pc, a)) >= 0) |
| { |
| if (r == 0) |
| { |
| swap(pc, pd); |
| pd -= es; |
| } |
| pc -= es; |
| } |
| if (pb > pc) |
| break; |
| swap(pb, pc); |
| pb += es; |
| pc -= es; |
| } |
| pn = (char *) a + n * es; |
| r = Min(pa - (char *) a, pb - pa); |
| vecswap(a, pb - r, r); |
| r = Min(pd - pc, pn - pd - es); |
| vecswap(pb, pn - r, r); |
| if ((r = pb - pa) > es) |
| qsort(a, r / es, es, cmp); |
| if ((r = pd - pc) > es) |
| { |
| /* Iterate rather than recurse to save stack space */ |
| a = pn - r; |
| n = r / es; |
| goto loop; |
| } |
| /* qsort(pn - r, r / es, es, cmp);*/ |
| } |