2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1992, 1993
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32 #if defined(LIBC_SCCS) && !defined(lint)
33 static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93";
34 #endif /* LIBC_SCCS and not lint */
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
41 typedef int cmp_t(void *, const void *, const void *);
43 typedef int cmp_t(const void *, const void *);
45 static inline char *med3(char *, char *, char *, cmp_t *, void *);
47 #define MIN(a, b) ((a) < (b) ? a : b)
50 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
54 swapfunc(char *a, char *b, size_t es)
65 #define vecswap(a, b, n) \
66 if ((n) > 0) swapfunc(a, b, n)
69 #define CMP(t, x, y) (cmp((t), (x), (y)))
71 #define CMP(t, x, y) (cmp((x), (y)))
75 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk
81 return CMP(thunk, a, b) < 0 ?
82 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a ))
83 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
88 qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
92 qsort(void *a, size_t n, size_t es, cmp_t *cmp)
95 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
103 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
105 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
107 swapfunc(pl, pl - es, es);
110 pm = (char *)a + (n / 2) * es;
113 pn = (char *)a + (n - 1) * es;
115 size_t d = (n / 8) * es;
117 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
118 pm = med3(pm - d, pm, pm + d, cmp, thunk);
119 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
121 pm = med3(pl, pm, pn, cmp, thunk);
124 pa = pb = (char *)a + es;
126 pc = pd = (char *)a + (n - 1) * es;
128 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
129 if (cmp_result == 0) {
131 swapfunc(pa, pb, es);
136 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
137 if (cmp_result == 0) {
139 swapfunc(pc, pd, es);
146 swapfunc(pb, pc, es);
151 if (swap_cnt == 0) { /* Switch to insertion sort */
152 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
154 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
156 swapfunc(pl, pl - es, es);
160 pn = (char *)a + n * es;
161 d1 = MIN(pa - (char *)a, pb - pa);
162 vecswap(a, pb - d1, d1);
163 d1 = MIN(pd - pc, pn - pd - es);
164 vecswap(pb, pn - d1, d1);
169 /* Recurse on left partition, then iterate on right partition */
172 qsort_r(a, d1 / es, es, thunk, cmp);
174 qsort(a, d1 / es, es, cmp);
178 /* Iterate rather than recurse to save stack space */
179 /* qsort(pn - d2, d2 / es, es, cmp); */
185 /* Recurse on right partition, then iterate on left partition */
188 qsort_r(pn - d2, d2 / es, es, thunk, cmp);
190 qsort(pn - d2, d2 / es, es, cmp);
194 /* Iterate rather than recurse to save stack space */
195 /* qsort(a, d1 / es, es, cmp); */