mirror of https://github.com/postgres/postgres
Bruce Momjian
23 years ago
parent
d7d741afbe
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33b3c95200
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/*
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* Copied from NetBSD CVS, 2002-07-19, bjm |
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* Add do ... while() macro fix |
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* Remove __inline, _DIAGASSERTs |
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*/ |
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/* $NetBSD: qsort.c,v 1.12 1999/09/20 04:39:40 lukem Exp $ */ |
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/*-
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* Copyright (c) 1992, 1993 |
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* The Regents of the University of California. All rights reserved. |
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* |
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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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* 1. 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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* 2. 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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* 3. All advertising materials mentioning features or use of this software |
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* must display the following acknowledgement: |
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* This product includes software developed by the University of |
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* California, Berkeley and its contributors. |
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* 4. Neither the name of the University nor the names of its contributors |
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* may be used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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*/ |
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#include <sys/cdefs.h> |
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#include <sys/types.h> |
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#include <assert.h> |
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#include <errno.h> |
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#include <stdlib.h> |
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static char *med3 __P((char *, char *, char *, |
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int (*) (const void *, const void *))); |
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static void swapfunc __P((char *, char *, size_t, int)); |
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#define min(a, b) (a) < (b) ? a : b |
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/*
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* Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". |
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*/ |
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#define swapcode(TYPE, parmi, parmj, n) \ |
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do { \
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size_t i = (n) / sizeof (TYPE); \
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TYPE *pi = (TYPE *)(void *)(parmi); \
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TYPE *pj = (TYPE *)(void *)(parmj); \
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do { \
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TYPE t = *pi; \
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*pi++ = *pj; \
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*pj++ = t; \
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} while (--i > 0); \
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} while (0) |
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#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ |
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es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; |
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static void |
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swapfunc(a, b, n, swaptype) |
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char *a, |
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*b; |
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size_t n; |
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int swaptype; |
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{ |
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if (swaptype <= 1) |
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swapcode(long, a, b, n); |
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else |
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swapcode(char, a, b, n); |
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} |
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#define swap(a, b) \ |
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if (swaptype == 0) { \
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long t = *(long *)(void *)(a); \
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*(long *)(void *)(a) = *(long *)(void *)(b); \
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*(long *)(void *)(b) = t; \
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} else \
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swapfunc(a, b, es, swaptype) |
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#define vecswap(a, b, n) if ((n) > 0) swapfunc((a), (b), (size_t)(n), swaptype) |
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static char * |
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med3(a, b, c, cmp) |
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char *a, |
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*b, |
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*c; |
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int (*cmp) __P((const void *, const void *)); |
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{ |
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return cmp(a, b) < 0 ? |
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(cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a)) |
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: (cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c)); |
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} |
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void |
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qsort(a, n, es, cmp) |
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void *a; |
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size_t n, |
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es; |
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int (*cmp) __P((const void *, const void *)); |
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{ |
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char *pa, |
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*pb, |
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*pc, |
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*pd, |
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*pl, |
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*pm, |
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*pn; |
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int d, |
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r, |
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swaptype, |
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swap_cnt; |
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loop:SWAPINIT(a, es); |
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swap_cnt = 0; |
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if (n < 7) |
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{ |
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for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) |
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for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; |
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pl -= es) |
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swap(pl, pl - es); |
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return; |
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} |
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pm = (char *) a + (n / 2) * es; |
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if (n > 7) |
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{ |
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pl = (char *) a; |
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pn = (char *) a + (n - 1) * es; |
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if (n > 40) |
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{ |
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d = (n / 8) * es; |
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pl = med3(pl, pl + d, pl + 2 * d, cmp); |
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pm = med3(pm - d, pm, pm + d, cmp); |
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pn = med3(pn - 2 * d, pn - d, pn, cmp); |
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} |
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pm = med3(pl, pm, pn, cmp); |
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} |
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swap(a, pm); |
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pa = pb = (char *) a + es; |
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pc = pd = (char *) a + (n - 1) * es; |
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for (;;) |
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{ |
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while (pb <= pc && (r = cmp(pb, a)) <= 0) |
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{ |
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if (r == 0) |
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{ |
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swap_cnt = 1; |
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swap(pa, pb); |
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pa += es; |
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} |
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pb += es; |
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} |
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while (pb <= pc && (r = cmp(pc, a)) >= 0) |
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{ |
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if (r == 0) |
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{ |
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swap_cnt = 1; |
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swap(pc, pd); |
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pd -= es; |
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} |
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pc -= es; |
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} |
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if (pb > pc) |
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break; |
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swap(pb, pc); |
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swap_cnt = 1; |
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pb += es; |
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pc -= es; |
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} |
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if (swap_cnt == 0) |
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{ /* Switch to insertion sort */ |
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for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) |
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for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; |
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pl -= es) |
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swap(pl, pl - es); |
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return; |
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} |
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pn = (char *) a + n * es; |
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r = min(pa - (char *) a, pb - pa); |
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vecswap(a, pb - r, r); |
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r = min(pd - pc, pn - pd - es); |
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vecswap(pb, pn - r, r); |
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if ((r = pb - pa) > es) |
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qsort(a, r / es, es, cmp); |
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if ((r = pd - pc) > es) |
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{ |
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/* Iterate rather than recurse to save stack space */ |
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a = pn - r; |
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n = r / es; |
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goto loop; |
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} |
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/* qsort(pn - r, r / es, es, cmp);*/ |
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} |
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