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1 | /* https://raw.githubusercontent.com/android/platform_bionic/master/libc/upstream-freebsd/lib/libc/stdlib/qsort.c */ |
2 | ||
3 | #define I_AM_QSORT_R | |
4 | ||
5 | /*- | |
6 | * Copyright (c) 1992, 1993 | |
7 | * The Regents of the University of California. All rights reserved. | |
8 | * | |
9 | * Redistribution and use in source and binary forms, with or without | |
10 | * modification, are permitted provided that the following conditions | |
11 | * are met: | |
12 | * 1. Redistributions of source code must retain the above copyright | |
13 | * notice, this list of conditions and the following disclaimer. | |
14 | * 2. Redistributions in binary form must reproduce the above copyright | |
15 | * notice, this list of conditions and the following disclaimer in the | |
16 | * documentation and/or other materials provided with the distribution. | |
17 | * 3. Neither the name of the University nor the names of its contributors | |
18 | * may be used to endorse or promote products derived from this software | |
19 | * without specific prior written permission. | |
20 | * | |
21 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
22 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
24 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
25 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
26 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
27 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
28 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
29 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
30 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
31 | * SUCH DAMAGE. | |
32 | */ | |
33 | ||
34 | #include <sys/cdefs.h> | |
35 | #include <stdlib.h> | |
36 | ||
37 | #ifdef I_AM_QSORT_R | |
38 | typedef int cmp_t(void *, const void *, const void *); | |
39 | #else | |
40 | typedef int cmp_t(const void *, const void *); | |
41 | #endif | |
42 | static inline char *med3(char *, char *, char *, cmp_t *, void *); | |
43 | static inline void swapfunc(char *, char *, int, int); | |
44 | ||
45 | #define min(a, b) (a) < (b) ? a : b | |
46 | ||
47 | /* | |
48 | * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". | |
49 | */ | |
50 | #define swapcode(TYPE, parmi, parmj, n) { \ | |
51 | long i = (n) / sizeof (TYPE); \ | |
52 | TYPE *pi = (TYPE *) (parmi); \ | |
53 | TYPE *pj = (TYPE *) (parmj); \ | |
54 | do { \ | |
55 | TYPE t = *pi; \ | |
56 | *pi++ = *pj; \ | |
57 | *pj++ = t; \ | |
58 | } while (--i > 0); \ | |
59 | } | |
60 | ||
61 | #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ | |
62 | es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; | |
63 | ||
64 | static inline void | |
65 | swapfunc(a, b, n, swaptype) | |
66 | char *a, *b; | |
67 | int n, swaptype; | |
68 | { | |
69 | if(swaptype <= 1) | |
70 | swapcode(long, a, b, n) | |
71 | else | |
72 | swapcode(char, a, b, n) | |
73 | } | |
74 | ||
75 | #define swap(a, b) \ | |
76 | if (swaptype == 0) { \ | |
77 | long t = *(long *)(a); \ | |
78 | *(long *)(a) = *(long *)(b); \ | |
79 | *(long *)(b) = t; \ | |
80 | } else \ | |
81 | swapfunc(a, b, es, swaptype) | |
82 | ||
83 | #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) | |
84 | ||
85 | #ifdef I_AM_QSORT_R | |
86 | #define CMP(t, x, y) (cmp((t), (x), (y))) | |
87 | #else | |
88 | #define CMP(t, x, y) (cmp((x), (y))) | |
89 | #endif | |
90 | ||
91 | static inline char * | |
92 | med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk | |
93 | #ifndef I_AM_QSORT_R | |
94 | __unused | |
95 | #endif | |
96 | ) | |
97 | { | |
98 | return CMP(thunk, a, b) < 0 ? | |
99 | (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a )) | |
100 | :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c )); | |
101 | } | |
102 | ||
103 | #ifdef I_AM_QSORT_R | |
104 | void | |
105 | qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) | |
106 | #else | |
107 | #define thunk NULL | |
108 | void | |
109 | qsort(void *a, size_t n, size_t es, cmp_t *cmp) | |
110 | #endif | |
111 | { | |
112 | char *pa, *pb, *pc, *pd, *pl, *pm, *pn; | |
113 | size_t d, r; | |
114 | int cmp_result; | |
115 | int swaptype, swap_cnt; | |
116 | ||
117 | loop: SWAPINIT(a, es); | |
118 | swap_cnt = 0; | |
119 | if (n < 7) { | |
120 | for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) | |
121 | for (pl = pm; | |
122 | pl > (char *)a && CMP(thunk, pl - es, pl) > 0; | |
123 | pl -= es) | |
124 | swap(pl, pl - es); | |
125 | return; | |
126 | } | |
127 | pm = (char *)a + (n / 2) * es; | |
128 | if (n > 7) { | |
129 | pl = a; | |
130 | pn = (char *)a + (n - 1) * es; | |
131 | if (n > 40) { | |
132 | d = (n / 8) * es; | |
133 | pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); | |
134 | pm = med3(pm - d, pm, pm + d, cmp, thunk); | |
135 | pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); | |
136 | } | |
137 | pm = med3(pl, pm, pn, cmp, thunk); | |
138 | } | |
139 | swap(a, pm); | |
140 | pa = pb = (char *)a + es; | |
141 | ||
142 | pc = pd = (char *)a + (n - 1) * es; | |
143 | for (;;) { | |
144 | while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) { | |
145 | if (cmp_result == 0) { | |
146 | swap_cnt = 1; | |
147 | swap(pa, pb); | |
148 | pa += es; | |
149 | } | |
150 | pb += es; | |
151 | } | |
152 | while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) { | |
153 | if (cmp_result == 0) { | |
154 | swap_cnt = 1; | |
155 | swap(pc, pd); | |
156 | pd -= es; | |
157 | } | |
158 | pc -= es; | |
159 | } | |
160 | if (pb > pc) | |
161 | break; | |
162 | swap(pb, pc); | |
163 | swap_cnt = 1; | |
164 | pb += es; | |
165 | pc -= es; | |
166 | } | |
167 | if (swap_cnt == 0) { /* Switch to insertion sort */ | |
168 | for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) | |
169 | for (pl = pm; | |
170 | pl > (char *)a && CMP(thunk, pl - es, pl) > 0; | |
171 | pl -= es) | |
172 | swap(pl, pl - es); | |
173 | return; | |
174 | } | |
175 | ||
176 | pn = (char *)a + n * es; | |
177 | r = min(pa - (char *)a, pb - pa); | |
178 | vecswap(a, pb - r, r); | |
179 | r = min(pd - pc, pn - pd - es); | |
180 | vecswap(pb, pn - r, r); | |
181 | if ((r = pb - pa) > es) | |
182 | #ifdef I_AM_QSORT_R | |
183 | qsort_r(a, r / es, es, thunk, cmp); | |
184 | #else | |
185 | qsort(a, r / es, es, cmp); | |
186 | #endif | |
187 | if ((r = pd - pc) > es) { | |
188 | /* Iterate rather than recurse to save stack space */ | |
189 | a = pn - r; | |
190 | n = r / es; | |
191 | goto loop; | |
192 | } | |
193 | /* qsort(pn - r, r / es, es, cmp);*/ | |
194 | } | |
195 |