282 lines
7.5 KiB
C
282 lines
7.5 KiB
C
/*-
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* Copyright (c) 1980, 1983 The Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms are permitted
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* provided that: (1) source distributions retain this entire copyright
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* notice and comment, and (2) distributions including binaries display
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* the following acknowledgement: ``This product includes software
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* developed by the University of California, Berkeley and its contributors''
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* in the documentation or other materials provided with the distribution
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* and in all advertising materials mentioning features or use of this
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* software. Neither the name of the University nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*/
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/* Modified by PerOla Valfridsson 910215 */
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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)qsort.c 5.7 (Berkeley) 5/17/90";
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#endif /* LIBC_SCCS and not lint */
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#define _KERNEL
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#include "ixemul.h"
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#include <stdlib.h>
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#ifdef NATIVE_MORPHOS
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#define qsort _qsort
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#define FLAGPRM ,int is68k
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#define FLAGARG , is68k
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/* code for:
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movem.l d0-d1,-(sp)
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jsr (a0)
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addq.l #8,sp
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rts
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*/
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static const UWORD cmp_gate[] = {
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0x48E7,0xC000,0x4E90,0x508F,0x4E75
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};
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static inline int my_cmp(const void *p, const void *q, int (*qcmp)(), int is68k) {
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if (is68k) {
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REG_D0 = (ULONG)p;
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REG_D1 = (ULONG)q;
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REG_A0 = (ULONG)qcmp;
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//REG_A4 = REG_A4;
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return MyEmulHandle->EmulCallDirect68k((APTR)cmp_gate);
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} else {
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return qcmp(p, q);
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}
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}
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#define CMP(x, y) my_cmp(x, y, qcmp, is68k)
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#else
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#define FLAGPRM
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#define FLAGARG
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#define CMP(x, y) qcmp(x, y)
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#endif
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static void qst(char *base, char *max, int (*qcmp)(), int qsz FLAGPRM);
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/*
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* qsort.c:
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* Our own version of the system qsort routine which is faster by an average
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* of 25%, with lows and highs of 10% and 50%.
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* The THRESHold below is the insertion sort threshold, and has been adjusted
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* for records of size 48 bytes.
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* The MTHREShold is where we stop finding a better median.
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*/
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#define THRESH 4 /* threshold for insertion */
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#define MTHRESH 6 /* threshold for median */
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/*
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* qsort:
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* First, set up some global parameters for qst to share. Then, quicksort
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* with qst(), and then a cleanup insertion sort ourselves. Sound simple?
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* It's not...
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*/
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void
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qsort(void *base, size_t n, size_t qsz, int (*qcmp)() FLAGPRM)
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{
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register char c, *i, *j, *lo, *hi;
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char *min, *max;
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if (n <= 1)
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return;
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max = base + n * qsz;
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if (n >= THRESH) {
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qst(base, max, qcmp, qsz FLAGARG);
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hi = base + qsz * THRESH;
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} else {
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hi = max;
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}
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/*
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* First put smallest element, which must be in the first THRESH, in
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* the first position as a sentinel. This is done just by searching
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* the first THRESH elements (or the first n if n < THRESH), finding
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* the min, and swapping it into the first position.
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*/
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for (j = lo = base; (lo += qsz) < hi; )
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if (CMP(j, lo) > 0)
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j = lo;
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if (j != base) {
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/* swap j into place */
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for (i = base, hi = base + qsz; i < hi; ) {
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c = *j;
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*j++ = *i;
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*i++ = c;
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}
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}
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/*
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* With our sentinel in place, we now run the following hyper-fast
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* insertion sort. For each remaining element, min, from [1] to [n-1],
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* set hi to the index of the element AFTER which this one goes.
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* Then, do the standard insertion sort shift on a character at a time
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* basis for each element in the frob.
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*/
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for (min = base; (hi = (min += qsz)) < max; ) {
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while (CMP((hi -= qsz), min) > 0)
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/* void */;
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if ((hi += qsz) != min) {
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for (lo = (min + qsz); --lo >= min; ) {
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c = *lo;
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for (i = j = lo; (j -= qsz) >= hi; i = j)
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*i = *j;
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*i = c;
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}
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}
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}
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}
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/*
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* qst:
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* Do a quicksort
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* First, find the median element, and put that one in the first place as the
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* discriminator. (This "median" is just the median of the first, last and
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* middle elements). (Using this median instead of the first element is a big
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* win). Then, the usual partitioning/swapping, followed by moving the
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* discriminator into the right place. Then, figure out the sizes of the two
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* partions, do the smaller one recursively and the larger one via a repeat of
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* this code. Stopping when there are less than THRESH elements in a partition
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* and cleaning up with an insertion sort (in our caller) is a huge win.
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* All data swaps are done in-line, which is space-losing but time-saving.
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* (And there are only three places where this is done).
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*/
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static void qst(char *base, char *max, int (*qcmp)(), int qsz FLAGPRM)
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{
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register char c, *i, *j, *jj;
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register int ii;
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char *mid, *tmp;
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int lo, hi;
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/*
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* At the top here, lo is the number of characters of elements in the
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* current partition. (Which should be max - base).
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* Find the median of the first, last, and middle element and make
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* that the middle element. Set j to largest of first and middle.
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* If max is larger than that guy, then it's that guy, else compare
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* max with loser of first and take larger. Things are set up to
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* prefer the middle, then the first in case of ties.
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*/
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lo = max - base; /* number of elements as chars */
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do {
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mid = i = base + qsz * ((lo / qsz) >> 1);
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if (lo >= qsz * MTHRESH) {
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j = (CMP((jj = base), i) > 0 ? jj : i);
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if (CMP(j, (tmp = max - qsz)) > 0) {
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/* switch to first loser */
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j = (j == jj ? i : jj);
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if (CMP(j, tmp) < 0)
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j = tmp;
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}
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if (j != i) {
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ii = qsz;
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do {
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c = *i;
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*i++ = *j;
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*j++ = c;
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} while (--ii);
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}
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}
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/*
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* Semi-standard quicksort partitioning/swapping
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*/
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for (i = base, j = max - qsz; ; ) {
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while (i < mid && CMP(i, mid) <= 0)
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i += qsz;
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while (j > mid) {
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if (CMP(mid, j) <= 0) {
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j -= qsz;
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continue;
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}
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tmp = i + qsz; /* value of i after swap */
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if (i == mid) {
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/* j <-> mid, new mid is j */
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mid = jj = j;
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} else {
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/* i <-> j */
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jj = j;
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j -= qsz;
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}
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goto swap;
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}
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if (i == mid) {
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break;
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} else {
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/* i <-> mid, new mid is i */
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jj = mid;
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tmp = mid = i; /* value of i after swap */
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j -= qsz;
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}
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swap:
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ii = qsz;
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do {
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c = *i;
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*i++ = *jj;
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*jj++ = c;
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} while (--ii);
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i = tmp;
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}
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/*
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* Look at sizes of the two partitions, do the smaller
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* one first by recursion, then do the larger one by
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* making sure lo is its size, base and max are update
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* correctly, and branching back. But only repeat
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* (recursively or by branching) if the partition is
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* of at least size THRESH.
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*/
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i = (j = mid) + qsz;
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if ((lo = j - base) <= (hi = max - i)) {
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if (lo >= qsz * THRESH)
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qst(base, j, qcmp, qsz FLAGARG);
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base = i;
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lo = hi;
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} else {
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if (hi >= qsz * THRESH)
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qst(i, max, qcmp, qsz FLAGARG);
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max = j;
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}
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} while (lo >= qsz * THRESH);
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}
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#ifdef NATIVE_MORPHOS
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#undef qsort
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#undef CMP
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#undef FLAGPRM
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#undef FLAGARG
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void
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qsort(void *base, size_t n, size_t qsz, int (*qcmp)())
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{
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_qsort(base, n, qsz, qcmp, 0);
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}
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void
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_trampoline_qsort(void)
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{
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int *p = (int *)REG_A7;
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void *base = (void *)p[1];
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size_t n = p[2];
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size_t qsz = p[3];
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int (*qcmp)() = (int(*)())p[4];
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_qsort(base, n, qsz, qcmp, 1);
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}
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const struct EmulLibEntry _gate_qsort = {
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TRAP_LIBNR, 0, (void(*)())_trampoline_qsort
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};
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#endif
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