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/*
FUNCTION
<<qsort>>---sort an array
 
INDEX
        qsort
 
ANSI_SYNOPSIS
        #include <stdlib.h>
        void qsort(void *<[base]>, size_t <[nmemb]>, size_t <[size]>,
                   int (*<[compar]>)(const void *, const void *) );
 
TRAD_SYNOPSIS
        #include <stdlib.h>
        qsort(<[base]>, <[nmemb]>, <[size]>, <[compar]> )
        char *<[base]>;
        size_t <[nmemb]>;
        size_t <[size]>;
        int (*<[compar]>)();
 
DESCRIPTION
<<qsort>> sorts an array (beginning at <[base]>) of <[nmemb]> objects.
<[size]> describes the size of each element of the array.
 
You must supply a pointer to a comparison function, using the argument
shown as <[compar]>.  (This permits sorting objects of unknown
properties.)  Define the comparison function to accept two arguments,
each a pointer to an element of the array starting at <[base]>.  The
result of <<(*<[compar]>)>> must be negative if the first argument is
less than the second, zero if the two arguments match, and positive if
the first argument is greater than the second (where ``less than'' and
``greater than'' refer to whatever arbitrary ordering is appropriate).
 
The array is sorted in place; that is, when <<qsort>> returns, the
array elements beginning at <[base]> have been reordered.
 
RETURNS
<<qsort>> does not return a result.
 
PORTABILITY
<<qsort>> is required by ANSI (without specifying the sorting algorithm).
*/
 
/*-
 * Copyright (c) 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
 
#include <_ansi.h>
#include <stdlib.h>
 
#ifndef __GNUC__
#define inline
#endif
 
static inline char      *med3 _PARAMS((char *, char *, char *, int (*)()));
static inline void       swapfunc _PARAMS((char *, char *, int, int));
 
#define min(a, b)       (a) < (b) ? a : b
 
/*
 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
 */
#define swapcode(TYPE, parmi, parmj, n) {               \
        long i = (n) / sizeof (TYPE);                   \
        register TYPE *pi = (TYPE *) (parmi);           \
        register TYPE *pj = (TYPE *) (parmj);           \
        do {                                            \
                register TYPE   t = *pi;                \
                *pi++ = *pj;                            \
                *pj++ = t;                              \
        } while (--i > 0);                               \
}
 
#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
        es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
 
static inline void
_DEFUN(swapfunc, (a, b, n, swaptype),
        char *a _AND
        char *b _AND
        int n _AND
        int swaptype)
{
        if(swaptype <= 1)
                swapcode(long, a, b, n)
        else
                swapcode(char, a, b, n)
}
 
#define swap(a, b)                                      \
        if (swaptype == 0) {                             \
                long t = *(long *)(a);                  \
                *(long *)(a) = *(long *)(b);            \
                *(long *)(b) = t;                       \
        } else                                          \
                swapfunc(a, b, es, swaptype)
 
#define vecswap(a, b, n)        if ((n) > 0) swapfunc(a, b, n, swaptype)
 
static inline char *
_DEFUN(med3, (a, b, c, cmp),
        char *a _AND
        char *b _AND
        char *c _AND
        int (*cmp)())
{
        return cmp(a, b) < 0 ?
               (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
              :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
}
 
void
_DEFUN(qsort, (a, n, es, cmp),
        void *a _AND
        size_t n _AND
        size_t es _AND
        int (*cmp)())
{
        char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
        int d, r, swaptype, swap_cnt;
 
loop:   SWAPINIT(a, es);
        swap_cnt = 0;
        if (n < 7) {
                for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
                        for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
                             pl -= es)
                                swap(pl, pl - es);
                return;
        }
        pm = (char *) a + (n / 2) * es;
        if (n > 7) {
                pl = a;
                pn = (char *) a + (n - 1) * es;
                if (n > 40) {
                        d = (n / 8) * es;
                        pl = med3(pl, pl + d, pl + 2 * d, cmp);
                        pm = med3(pm - d, pm, pm + d, cmp);
                        pn = med3(pn - 2 * d, pn - d, pn, cmp);
                }
                pm = med3(pl, pm, pn, cmp);
        }
        swap(a, pm);
        pa = pb = (char *) a + es;
 
        pc = pd = (char *) a + (n - 1) * es;
        for (;;) {
                while (pb <= pc && (r = cmp(pb, a)) <= 0) {
                        if (r == 0) {
                                swap_cnt = 1;
                                swap(pa, pb);
                                pa += es;
                        }
                        pb += es;
                }
                while (pb <= pc && (r = cmp(pc, a)) >= 0) {
                        if (r == 0) {
                                swap_cnt = 1;
                                swap(pc, pd);
                                pd -= es;
                        }
                        pc -= es;
                }
                if (pb > pc)
                        break;
                swap(pb, pc);
                swap_cnt = 1;
                pb += es;
                pc -= es;
        }
        if (swap_cnt == 0) {  /* Switch to insertion sort */
                for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
                        for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
                             pl -= es)
                                swap(pl, pl - es);
                return;
        }
 
        pn = (char *) a + n * es;
        r = min(pa - (char *)a, pb - pa);
        vecswap(a, pb - r, r);
        r = min(pd - pc, pn - pd - es);
        vecswap(pb, pn - r, r);
        if ((r = pb - pa) > es)
                qsort(a, r / es, es, cmp);
        if ((r = pd - pc) > es) {
                /* Iterate rather than recurse to save stack space */
                a = pn - r;
                n = r / es;
                goto loop;
        }
/*              qsort(pn - r, r / es, es, cmp);*/
}

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[/] [or1k/] [trunk/] [newlib/] [newlib/] [libc/] [stdlib/] [qsort.c] - Blame information for rev 1777

Line No.	Rev	Author	Line
1	39	lampret	`/*`
2			`FUNCTION`
3			`<<qsort>>---sort an array`
4
5			`INDEX`
6			`qsort`
7
8			`ANSI_SYNOPSIS`
9			`#include <stdlib.h>`
10			`void qsort(void *<[base]>, size_t <[nmemb]>, size_t <[size]>,`
11			`int (<[compar]>)(const void , const void *) );`
12
13			`TRAD_SYNOPSIS`
14			`#include <stdlib.h>`
15			`qsort(<[base]>, <[nmemb]>, <[size]>, <[compar]> )`
16			`char *<[base]>;`
17			`size_t <[nmemb]>;`
18			`size_t <[size]>;`
19			`int (*<[compar]>)();`
20
21			`DESCRIPTION`
22			`<<qsort>> sorts an array (beginning at <[base]>) of <[nmemb]> objects.`
23			`<[size]> describes the size of each element of the array.`
24
25			`You must supply a pointer to a comparison function, using the argument`
26			`shown as <[compar]>. (This permits sorting objects of unknown`
27			`properties.) Define the comparison function to accept two arguments,`
28			`each a pointer to an element of the array starting at <[base]>. The`
29			`result of <<(*<[compar]>)>> must be negative if the first argument is`
30			`less than the second, zero if the two arguments match, and positive if`
31			the first argument is greater than the second (where ``less than'' and
32			``greater than'' refer to whatever arbitrary ordering is appropriate).
33
34			`The array is sorted in place; that is, when <<qsort>> returns, the`
35			`array elements beginning at <[base]> have been reordered.`
36
37			`RETURNS`
38			`<<qsort>> does not return a result.`
39
40			`PORTABILITY`
41			`<<qsort>> is required by ANSI (without specifying the sorting algorithm).`
42			`*/`
43
44			`/*-`
45			`* Copyright (c) 1992, 1993`
46			`* The Regents of the University of California. All rights reserved.`
47			`*`
48			`* Redistribution and use in source and binary forms, with or without`
49			`* modification, are permitted provided that the following conditions`
50			`* are met:`
51			`* 1. Redistributions of source code must retain the above copyright`
52			`* notice, this list of conditions and the following disclaimer.`
53			`* 2. Redistributions in binary form must reproduce the above copyright`
54			`* notice, this list of conditions and the following disclaimer in the`
55			`* documentation and/or other materials provided with the distribution.`
56			`* 3. All advertising materials mentioning features or use of this software`
57			`* must display the following acknowledgement:`
58			`* This product includes software developed by the University of`
59			`* California, Berkeley and its contributors.`
60			`* 4. Neither the name of the University nor the names of its contributors`
61			`* may be used to endorse or promote products derived from this software`
62			`* without specific prior written permission.`
63			`*`
64			* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
65			`* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE`
66			`* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE`
67			`* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE`
68			`* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL`
69			`* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS`
70			`* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)`
71			`* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT`
72			`* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY`
73			`* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF`
74			`* SUCH DAMAGE.`
75			`*/`
76
77			`#include <_ansi.h>`
78			`#include <stdlib.h>`
79
80			`#ifndef __GNUC__`
81			`#define inline`
82			`#endif`
83
84			`static inline char med3 _PARAMS((char , char , char , int (*)()));`
85			`static inline void swapfunc _PARAMS((char , char , int, int));`
86
87			`#define min(a, b) (a) < (b) ? a : b`
88
89			`/*`
90			`* Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".`
91			`*/`
92			`#define swapcode(TYPE, parmi, parmj, n) { \`
93			`long i = (n) / sizeof (TYPE); \`
94			`register TYPE pi = (TYPE ) (parmi); \`
95			`register TYPE pj = (TYPE ) (parmj); \`
96			`do { \`
97			`register TYPE t = *pi; \`
98			`pi++ = pj; \`
99			`*pj++ = t; \`
100			`} while (--i > 0); \`
101			`}`
102
103			`#define SWAPINIT(a, es) swaptype = ((char )a - (char )0) % sizeof(long) \|\| \`
104			`es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;`
105
106			`static inline void`
107			`_DEFUN(swapfunc, (a, b, n, swaptype),`
108			`char *a _AND`
109			`char *b _AND`
110			`int n _AND`
111			`int swaptype)`
112			`{`
113			`if(swaptype <= 1)`
114			`swapcode(long, a, b, n)`
115			`else`
116			`swapcode(char, a, b, n)`
117			`}`
118
119			`#define swap(a, b) \`
120			`if (swaptype == 0) { \`
121			`long t = (long )(a); \`
122			`(long )(a) = (long )(b); \`
123			`(long )(b) = t; \`
124			`} else \`
125			`swapfunc(a, b, es, swaptype)`
126
127			`#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)`
128
129			`static inline char *`
130			`_DEFUN(med3, (a, b, c, cmp),`
131			`char *a _AND`
132			`char *b _AND`
133			`char *c _AND`
134			`int (*cmp)())`
135			`{`
136			`return cmp(a, b) < 0 ?`
137			`(cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))`
138			`:(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));`
139			`}`
140
141			`void`
142			`_DEFUN(qsort, (a, n, es, cmp),`
143			`void *a _AND`
144			`size_t n _AND`
145			`size_t es _AND`
146			`int (*cmp)())`
147			`{`
148			`char pa, pb, pc, pd, pl, pm, *pn;`
149			`int d, r, swaptype, swap_cnt;`
150
151			`loop: SWAPINIT(a, es);`
152			`swap_cnt = 0;`
153			`if (n < 7) {`
154			`for (pm = (char ) a + es; pm < (char ) a + n * es; pm += es)`
155			`for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;`
156			`pl -= es)`
157			`swap(pl, pl - es);`
158			`return;`
159			`}`
160			`pm = (char ) a + (n / 2) es;`
161			`if (n > 7) {`
162			`pl = a;`
163			`pn = (char ) a + (n - 1) es;`
164			`if (n > 40) {`
165			`d = (n / 8) * es;`
166			`pl = med3(pl, pl + d, pl + 2 * d, cmp);`
167			`pm = med3(pm - d, pm, pm + d, cmp);`
168			`pn = med3(pn - 2 * d, pn - d, pn, cmp);`
169			`}`
170			`pm = med3(pl, pm, pn, cmp);`
171			`}`
172			`swap(a, pm);`
173			`pa = pb = (char *) a + es;`
174
175			`pc = pd = (char ) a + (n - 1) es;`
176			`for (;;) {`
177			`while (pb <= pc && (r = cmp(pb, a)) <= 0) {`
178			`if (r == 0) {`
179			`swap_cnt = 1;`
180			`swap(pa, pb);`
181			`pa += es;`
182			`}`
183			`pb += es;`
184			`}`
185			`while (pb <= pc && (r = cmp(pc, a)) >= 0) {`
186			`if (r == 0) {`
187			`swap_cnt = 1;`
188			`swap(pc, pd);`
189			`pd -= es;`
190			`}`
191			`pc -= es;`
192			`}`
193			`if (pb > pc)`
194			`break;`
195			`swap(pb, pc);`
196			`swap_cnt = 1;`
197			`pb += es;`
198			`pc -= es;`
199			`}`
200			`if (swap_cnt == 0) { /* Switch to insertion sort */`
201			`for (pm = (char ) a + es; pm < (char ) a + n * es; pm += es)`
202			`for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;`
203			`pl -= es)`
204			`swap(pl, pl - es);`
205			`return;`
206			`}`
207
208			`pn = (char ) a + n es;`
209			`r = min(pa - (char *)a, pb - pa);`
210			`vecswap(a, pb - r, r);`
211			`r = min(pd - pc, pn - pd - es);`
212			`vecswap(pb, pn - r, r);`
213			`if ((r = pb - pa) > es)`
214			`qsort(a, r / es, es, cmp);`
215			`if ((r = pd - pc) > es) {`
216			`/* Iterate rather than recurse to save stack space */`
217			`a = pn - r;`
218			`n = r / es;`
219			`goto loop;`
220			`}`
221			`/* qsort(pn - r, r / es, es, cmp);*/`
222			`}`