added alg_sort.c
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321
qse/lib/cmn/alg_sort.c
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321
qse/lib/cmn/alg_sort.c
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/*
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* $Id$
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*
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Copyright 2006-2009 Chung, Hyung-Hwan.
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This file is part of QSE.
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QSE is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation, either version 3 of
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the License, or (at your option) any later version.
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QSE is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with QSE. If not, see <http://www.gnu.org/licenses/>.
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*/
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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 <qse/cmn/alg.h>
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#define qsort_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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qse_size_t i = (n) / sizeof (TYPE); \
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register TYPE *pi = (TYPE*)(parmi); \
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register TYPE *pj = (TYPE*)(parmj); \
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do { \
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register 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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}
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#define SWAPINIT(a,size) \
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swaptype = ((qse_byte_t*)a-(qse_byte_t*)0)%sizeof(long) || \
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size % sizeof(long) ? 2 : size == sizeof(long)? 0 : 1;
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static QSE_INLINE void swapfunc (
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qse_byte_t* a, qse_byte_t* b, int 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(qse_byte_t, 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*)(a); \
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*(long*)(a) = *(long*)(b); \
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*(long*)(b) = t; \
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} else swapfunc(a, b, size, swaptype)
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#define vecswap(a,b,n) if ((n) > 0) swapfunc(a, b, n, swaptype)
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static QSE_INLINE qse_byte_t* med3 (
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qse_byte_t* a, qse_byte_t* b, qse_byte_t* c,
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qse_sort_comper_t comper, void* ctx)
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{
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if (comper(a, b, ctx) < 0)
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{
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if (comper(b, c, ctx) < 0) return b;
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return (comper(a, c, ctx) < 0)? c: a;
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}
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else
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{
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if (comper(b, c, ctx) > 0) return b;
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return (comper(a, c, ctx) > 0)? c: a;
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}
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}
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void qse_qsort (
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void* base, qse_size_t nmemb, qse_size_t size,
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qse_sort_comper_t comper, void* ctx)
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{
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qse_byte_t*pa, *pb, *pc, *pd, *pl, *pm, *pn;
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int swaptype, swap_cnt;
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long r;
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qse_size_t d;
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register qse_byte_t*a = (qse_byte_t*)base;
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loop:
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SWAPINIT(a, size);
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swap_cnt = 0;
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if (nmemb < 7)
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{
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for (pm = (qse_byte_t*)a + size;
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pm < (qse_byte_t*) a + nmemb * size; pm += size)
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{
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for (pl = pm; pl > (qse_byte_t*)a &&
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comper(pl - size, pl, ctx) > 0; pl -= size)
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{
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swap(pl, pl - size);
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}
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}
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return;
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}
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pm = (qse_byte_t*)a + (nmemb / 2) * size;
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if (nmemb > 7)
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{
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pl = (qse_byte_t*)a;
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pn = (qse_byte_t*)a + (nmemb - 1) * size;
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if (nmemb > 40)
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{
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d = (nmemb / 8) * size;
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pl = med3(pl, pl + d, pl + 2 * d, comper, ctx);
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pm = med3(pm - d, pm, pm + d, comper, ctx);
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pn = med3(pn - 2 * d, pn - d, pn, comper, ctx);
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}
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pm = med3(pl, pm, pn, comper, ctx);
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}
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swap(a, pm);
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pa = pb = (qse_byte_t*)a + size;
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pc = pd = (qse_byte_t*)a + (nmemb - 1) * size;
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for (;;)
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{
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while (pb <= pc && (r = comper(pb, a, ctx)) <= 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 += size;
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}
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pb += size;
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}
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while (pb <= pc && (r = comper(pc, a, ctx)) >= 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 -= size;
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}
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pc -= size;
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}
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if (pb > pc) break;
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swap (pb, pc);
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swap_cnt = 1;
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pb += size;
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pc -= size;
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}
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if (swap_cnt == 0)
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{
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/* switch to insertion sort */
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for (pm = (qse_byte_t*)a + size;
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pm < (qse_byte_t*)a + nmemb * size; pm += size)
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{
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for (pl = pm; pl > (qse_byte_t*)a &&
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comper(pl - size, pl, ctx) > 0; pl -= size)
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{
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swap(pl, pl - size);
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}
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}
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return;
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}
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pn = (qse_byte_t*)a + nmemb * size;
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r = qsort_min(pa - (qse_byte_t*)a, pb - pa);
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vecswap (a, pb - r, r);
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r = qsort_min (pd - pc, pn - pd - size);
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vecswap (pb, pn - r, r);
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if ((r = pb - pa) > size) qse_qsort(a, r / size, size, comper, ctx);
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if ((r = pd - pc) > size)
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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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nmemb = r / size;
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goto loop;
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}
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/* qsort(pn - r, r / size, size, comper);*/
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}
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#if 0
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/*
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* Below is an example of a naive qsort implementation
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*/
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#define swap(a,b,size) \
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do { \
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qse_size_t i = 0; \
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qse_byte_t* p1 = (a); \
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qse_byte_t* p2 = (b); \
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for (i = 0; i < size; i++) { \
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qse_byte_t t = *p1; \
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*p1 = *p2; \
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*p2 = t; \
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p1++; p2++; \
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} \
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} while (0)
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#define REF(x,i) (&((x)[(i)*size]))
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void qse_qsort (void* base, qse_size_t nmemb, qse_size_t size, void* arg,
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int (*compar)(const void*, const void*, void*))
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{
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qse_size_t pivot, start, end;
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qse_byte_t* p = (qse_byte_t*)base;
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if (nmemb <= 1) return;
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if (nmemb == 2) {
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if (compar(REF(p,0), REF(p,1), arg) > 0)
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swap (REF(p,0), REF(p,1), size);
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return;
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}
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pivot = nmemb >> 1; /* choose the middle as the pivot index */
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swap (REF(p,pivot), REF(p,nmemb-1), size); /* swap the pivot with the last item */
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start = 0; end = nmemb - 2;
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while (1) {
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/* look for the larger value than pivot */
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while (start <= end &&
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compar(REF(p,start), REF(p,nmemb-1), arg) <= 0) start++;
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/* look for the less value than pivot. */
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while (end > start &&
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compar(REF(p,end), REF(p,nmemb-1), arg) >= 0) end--;
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if (start >= end) break; /* no more to swap */
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swap (REF(p,start), REF(p,end), size);
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start++; end--;
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}
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swap (REF(p,nmemb-1), REF(p,start), size);
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pivot = start; /* adjust the pivot index */
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qse_qsort (REF(p,0), pivot, size, arg, compar);
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qse_qsort (REF(p,pivot+1), nmemb - pivot - 1, size, arg, compar);
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}
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/*
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* For easier understanding, see the following
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*/
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#define swap(a, b) do { a ^= b; b ^= a; a ^= b; } while (0)
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void qsort (int* x, size_t n)
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{
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size_t index, start, end;
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int pivot;
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if (n <= 1) return;
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if (n == 2) {
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if (x[0] > x[1]) swap (x[0], x[1]);
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return;
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}
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index = n / 2; /* choose the middle as the pivot index */
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pivot = x[index]; /* store the pivot value */
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swap (x[index], x[n - 1]); /* swap the pivot with the last item */
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start = 0; end = n - 2;
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while (1) {
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/* look for the larger value than pivot */
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while (start <= end && x[start] <= pivot) start++;
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/* look for the less value than pivot. */
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while (end > start && x[end] >= pivot) end--;
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if (start >= end) {
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/* less values all on the left,
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* larger values all on the right
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*/
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break;
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}
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swap (x[start], x[end]);
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start++; end--;
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}
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x[n - 1] = x[start]; /* restore the pivot value */
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x[start] = pivot;
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index = start; /* adjust the pivot index */
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qsort (x, index);
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qsort (&x[index + 1], n - index - 1);
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}
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#endif
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