mirror of https://github.com/postgres/postgres
repeatedly. Now that we don't have to worry about memory leaks from glibc's qsort, we can safely put CHECK_FOR_INTERRUPTS into the tuplesort comparators, as was requested a couple months ago. Also, get rid of non-reentrancy and an extra level of function call in tuplesort.c by providing a variant qsort_arg() API that passes an extra void * argument through to the comparison routine. (We might want to use that in other places too, I didn't look yet.)REL8_2_STABLE
Tom Lane
19 years ago
parent
ed80f5701b
commit
6edd2b4a91
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/*
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* qsort_arg.c: qsort with a passthrough "void *" argument |
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* |
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* Modifications from vanilla NetBSD source: |
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* Add do ... while() macro fix |
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* Remove __inline, _DIAGASSERTs, __P |
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* Remove ill-considered "swap_cnt" switch to insertion sort, |
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* in favor of a simple check for presorted input. |
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* |
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* CAUTION: if you change this file, see also qsort.c |
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* |
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* $PostgreSQL: pgsql/src/port/qsort_arg.c,v 1.1 2006/10/03 22:18:23 tgl Exp $ |
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*/ |
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/* $NetBSD: qsort.c,v 1.13 2003/08/07 16:43:42 agc 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. 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 "c.h" |
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static char *med3(char *a, char *b, char *c, |
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qsort_arg_comparator cmp, void *arg); |
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static void swapfunc(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 based on J. L. Bentley and M. D. McIlroy, |
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* "Engineering a sort function", |
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* Software--Practice and Experience 23 (1993) 1249-1265. |
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* We have modified their original by adding a check for already-sorted input, |
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* which seems to be a win per discussions on pgsql-hackers around 2006-03-21. |
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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(char *a, char *b, char *c, qsort_arg_comparator cmp, void *arg) |
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{ |
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return cmp(a, b, arg) < 0 ? |
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(cmp(b, c, arg) < 0 ? b : (cmp(a, c, arg) < 0 ? c : a)) |
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: (cmp(b, c, arg) > 0 ? b : (cmp(a, c, arg) < 0 ? a : c)); |
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} |
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|
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void |
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qsort_arg(void *a, size_t n, size_t es, qsort_arg_comparator cmp, void *arg) |
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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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presorted; |
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loop:SWAPINIT(a, es); |
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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, arg) > 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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presorted = 1; |
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for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) |
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{ |
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if (cmp(pm - es, pm, arg) > 0) |
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{ |
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presorted = 0; |
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break; |
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} |
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} |
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if (presorted) |
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return; |
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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, arg); |
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pm = med3(pm - d, pm, pm + d, cmp, arg); |
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pn = med3(pn - 2 * d, pn - d, pn, cmp, arg); |
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} |
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pm = med3(pl, pm, pn, cmp, arg); |
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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, arg)) <= 0) |
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{ |
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if (r == 0) |
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{ |
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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, arg)) >= 0) |
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{ |
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if (r == 0) |
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{ |
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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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pb += es; |
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pc -= es; |
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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_arg(a, r / es, es, cmp, arg); |
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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_arg(pn - r, r / es, es, cmp, arg);*/ |
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} |
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