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A modern Music Player Daemon based on Rockbox open source high quality audio player
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1/*
2FUNCTION
3<<qsort>>---sort an array
4
5INDEX
6 qsort
7
8ANSI_SYNOPSIS
9 #include <stdlib.h>
10 void qsort(void *<[base]>, size_t <[nmemb]>, size_t <[size]>,
11 int (*<[compar]>)(const void *, const void *) );
12
13TRAD_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
21DESCRIPTION
22<<qsort>> sorts an array (beginning at <[base]>) of <[nmemb]> objects.
23<[size]> describes the size of each element of the array.
24
25You must supply a pointer to a comparison function, using the argument
26shown as <[compar]>. (This permits sorting objects of unknown
27properties.) Define the comparison function to accept two arguments,
28each a pointer to an element of the array starting at <[base]>. The
29result of <<(*<[compar]>)>> must be negative if the first argument is
30less than the second, zero if the two arguments match, and positive if
31the first argument is greater than the second (where ``less than'' and
32``greater than'' refer to whatever arbitrary ordering is appropriate).
33
34The array is sorted in place; that is, when <<qsort>> returns, the
35array elements beginning at <[base]> have been reordered.
36
37RETURNS
38<<qsort>> does not return a result.
39
40PORTABILITY
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
84static inline char *med3 _PARAMS((char *, char *, char *, int (*cmp)(const _PTR,const _PTR)));
85static 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
106static 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
129static inline char *
130_DEFUN(med3, (a, b, c, cmp),
131 char *a _AND
132 char *b _AND
133 char *c _AND
134 int (*cmp)(const _PTR,const _PTR))
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
141void
142_DEFUN(qsort, (a, n, es, cmp),
143 void *a _AND
144 size_t n _AND
145 size_t es _AND
146 int (*cmp)(const _PTR,const _PTR))
147{
148 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
149 int d, r, swaptype, swap_cnt;
150
151loop: 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((unsigned int)(pd - pc), pn - pd - es);
212 vecswap(pb, pn - r, r);
213 if ((unsigned int)(r = pb - pa) > es)
214 qsort(a, r / es, es, cmp);
215 if ((unsigned int)(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}