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This includes removing tabs after periods in C comments, which was applied to back branches, so this change should not effect backpatching.
205 lines
5.3 KiB
C
205 lines
5.3 KiB
C
/*
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* qsort.c: standard quicksort algorithm
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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_arg.c, gen_qsort_tuple.pl
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*
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* src/port/qsort.c
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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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int (*cmp) (const void *, const void *));
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static void swapfunc(char *, char *, size_t, int);
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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(char *a, char *b, size_t n, 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, int (*cmp) (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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pg_qsort(void *a, size_t n, size_t es, int (*cmp) (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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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) > 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) > 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);
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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(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(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(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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/*
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* qsort wrapper for strcmp.
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*/
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int
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pg_qsort_strcmp(const void *a, const void *b)
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{
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return strcmp(*(char *const *) a, *(char *const *) b);
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}
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