273 lines
6.9 KiB
Perl
273 lines
6.9 KiB
Perl
#!/usr/bin/perl
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#
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# gen_qsort_tuple.pl
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#
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# This script generates specialized versions of the quicksort algorithm for
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# tuple sorting. The quicksort code is derived from the NetBSD code. The
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# code generated by this script runs significantly faster than vanilla qsort
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# when used to sort tuples. This speedup comes from a number of places.
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# The major effects are (1) inlining simple tuple comparators is much faster
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# than jumping through a function pointer and (2) swap and vecswap operations
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# specialized to the particular data type of interest (in this case, SortTuple)
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# are faster than the generic routines.
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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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# Take care to recurse on the smaller partition, to bound stack usage.
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#
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# Instead of sorting arbitrary objects, we're always sorting SortTuples.
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# Add CHECK_FOR_INTERRUPTS().
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#
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# CAUTION: if you change this file, see also qsort.c and qsort_arg.c
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#
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use strict;
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use warnings;
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my $SUFFIX;
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my $EXTRAARGS;
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my $EXTRAPARAMS;
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my $CMPPARAMS;
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emit_qsort_boilerplate();
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$SUFFIX = 'tuple';
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$EXTRAARGS = ', SortTupleComparator cmp_tuple, Tuplesortstate *state';
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$EXTRAPARAMS = ', cmp_tuple, state';
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$CMPPARAMS = ', state';
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emit_qsort_implementation();
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$SUFFIX = 'ssup';
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$EXTRAARGS = ', SortSupport ssup';
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$EXTRAPARAMS = ', ssup';
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$CMPPARAMS = ', ssup';
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print <<'EOM';
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#define cmp_ssup(a, b, ssup) \
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ApplySortComparator((a)->datum1, (a)->isnull1, \
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(b)->datum1, (b)->isnull1, ssup)
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EOM
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emit_qsort_implementation();
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sub emit_qsort_boilerplate
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{
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print <<'EOM';
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/*
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* autogenerated by src/backend/utils/sort/gen_qsort_tuple.pl, do not edit!
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*
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* This file is included by tuplesort.c, rather than compiled separately.
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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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/*
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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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*
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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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* Also, we recurse on the smaller partition and iterate on the larger one,
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* which ensures we cannot recurse more than log(N) levels (since the
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* partition recursed to is surely no more than half of the input). Bentley
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* and McIlroy explicitly rejected doing this on the grounds that it's "not
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* worth the effort", but we have seen crashes in the field due to stack
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* overrun, so that judgment seems wrong.
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*/
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static void
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swapfunc(SortTuple *a, SortTuple *b, size_t n)
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{
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do
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{
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SortTuple t = *a;
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*a++ = *b;
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*b++ = t;
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} while (--n > 0);
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}
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#define swap(a, b) \
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do { \
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SortTuple t = *(a); \
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*(a) = *(b); \
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*(b) = t; \
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} while (0)
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#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n)
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EOM
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return;
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}
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sub emit_qsort_implementation
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{
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print <<EOM;
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static SortTuple *
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med3_$SUFFIX(SortTuple *a, SortTuple *b, SortTuple *c$EXTRAARGS)
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{
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return cmp_$SUFFIX(a, b$CMPPARAMS) < 0 ?
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(cmp_$SUFFIX(b, c$CMPPARAMS) < 0 ? b :
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(cmp_$SUFFIX(a, c$CMPPARAMS) < 0 ? c : a))
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: (cmp_$SUFFIX(b, c$CMPPARAMS) > 0 ? b :
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(cmp_$SUFFIX(a, c$CMPPARAMS) < 0 ? a : c));
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}
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static void
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qsort_$SUFFIX(SortTuple *a, size_t n$EXTRAARGS)
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{
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SortTuple *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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size_t d1,
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d2;
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int r,
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presorted;
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loop:
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CHECK_FOR_INTERRUPTS();
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if (n < 7)
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{
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for (pm = a + 1; pm < a + n; pm++)
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for (pl = pm; pl > a && cmp_$SUFFIX(pl - 1, pl$CMPPARAMS) > 0; pl--)
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swap(pl, pl - 1);
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return;
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}
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presorted = 1;
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for (pm = a + 1; pm < a + n; pm++)
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{
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CHECK_FOR_INTERRUPTS();
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if (cmp_$SUFFIX(pm - 1, pm$CMPPARAMS) > 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 = a + (n / 2);
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if (n > 7)
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{
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pl = a;
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pn = a + (n - 1);
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if (n > 40)
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{
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size_t d = (n / 8);
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pl = med3_$SUFFIX(pl, pl + d, pl + 2 * d$EXTRAPARAMS);
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pm = med3_$SUFFIX(pm - d, pm, pm + d$EXTRAPARAMS);
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pn = med3_$SUFFIX(pn - 2 * d, pn - d, pn$EXTRAPARAMS);
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}
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pm = med3_$SUFFIX(pl, pm, pn$EXTRAPARAMS);
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}
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swap(a, pm);
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pa = pb = a + 1;
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pc = pd = a + (n - 1);
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for (;;)
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{
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while (pb <= pc && (r = cmp_$SUFFIX(pb, a$CMPPARAMS)) <= 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++;
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}
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pb++;
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CHECK_FOR_INTERRUPTS();
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}
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while (pb <= pc && (r = cmp_$SUFFIX(pc, a$CMPPARAMS)) >= 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--;
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}
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pc--;
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CHECK_FOR_INTERRUPTS();
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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++;
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pc--;
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}
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pn = a + n;
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d1 = Min(pa - a, pb - pa);
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vecswap(a, pb - d1, d1);
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d1 = Min(pd - pc, pn - pd - 1);
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vecswap(pb, pn - d1, d1);
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d1 = pb - pa;
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d2 = pd - pc;
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if (d1 <= d2)
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{
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/* Recurse on left partition, then iterate on right partition */
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if (d1 > 1)
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qsort_$SUFFIX(a, d1$EXTRAPARAMS);
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if (d2 > 1)
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{
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/* Iterate rather than recurse to save stack space */
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/* qsort_$SUFFIX(pn - d2, d2$EXTRAPARAMS); */
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a = pn - d2;
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n = d2;
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goto loop;
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}
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}
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else
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{
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/* Recurse on right partition, then iterate on left partition */
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if (d2 > 1)
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qsort_$SUFFIX(pn - d2, d2$EXTRAPARAMS);
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if (d1 > 1)
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{
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/* Iterate rather than recurse to save stack space */
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/* qsort_$SUFFIX(a, d1$EXTRAPARAMS); */
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n = d1;
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goto loop;
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}
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}
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}
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EOM
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return;
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}
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