2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1992, 1993
5 * The Regents of the University of California. All rights reserved.
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8 * modification, are permitted provided that the following conditions
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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("$FreeBSD$");
42 #include "libc_private.h"
44 #if defined(I_AM_QSORT_R)
45 typedef int cmp_t(void *, const void *, const void *);
46 #elif defined(I_AM_QSORT_S)
47 typedef int cmp_t(const void *, const void *, void *);
49 typedef int cmp_t(const void *, const void *);
51 static inline char *med3(char *, char *, char *, cmp_t *, void *);
53 #define MIN(a, b) ((a) < (b) ? a : b)
56 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
60 swapfunc(char *a, char *b, size_t es)
71 #define vecswap(a, b, n) \
72 if ((n) > 0) swapfunc(a, b, n)
74 #if defined(I_AM_QSORT_R)
75 #define CMP(t, x, y) (cmp((t), (x), (y)))
76 #elif defined(I_AM_QSORT_S)
77 #define CMP(t, x, y) (cmp((x), (y), (t)))
79 #define CMP(t, x, y) (cmp((x), (y)))
83 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk
84 #if !defined(I_AM_QSORT_R) && !defined(I_AM_QSORT_S)
89 return CMP(thunk, a, b) < 0 ?
90 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a ))
91 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
95 * The actual qsort() implementation is static to avoid preemptible calls when
96 * recursing. Also give them different names for improved debugging.
98 #if defined(I_AM_QSORT_R)
99 #define local_qsort local_qsort_r
100 #elif defined(I_AM_QSORT_S)
101 #define local_qsort local_qsort_s
104 local_qsort(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk)
106 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
111 if (__predict_false(n == 0))
116 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
118 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
120 swapfunc(pl, pl - es, es);
123 pm = (char *)a + (n / 2) * es;
126 pn = (char *)a + (n - 1) * es;
128 size_t d = (n / 8) * es;
130 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
131 pm = med3(pm - d, pm, pm + d, cmp, thunk);
132 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
134 pm = med3(pl, pm, pn, cmp, thunk);
137 pa = pb = (char *)a + es;
139 pc = pd = (char *)a + (n - 1) * es;
141 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
142 if (cmp_result == 0) {
144 swapfunc(pa, pb, es);
149 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
150 if (cmp_result == 0) {
152 swapfunc(pc, pd, es);
159 swapfunc(pb, pc, es);
164 if (swap_cnt == 0) { /* Switch to insertion sort */
165 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
167 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
169 swapfunc(pl, pl - es, es);
173 pn = (char *)a + n * es;
174 d1 = MIN(pa - (char *)a, pb - pa);
175 vecswap(a, pb - d1, d1);
177 * Cast es to preserve signedness of right-hand side of MIN()
178 * expression, to avoid sign ambiguity in the implied comparison. es
179 * is safely within [0, SSIZE_MAX].
181 d1 = MIN(pd - pc, pn - pd - (ssize_t)es);
182 vecswap(pb, pn - d1, d1);
187 /* Recurse on left partition, then iterate on right partition */
189 local_qsort(a, d1 / es, es, cmp, thunk);
192 /* Iterate rather than recurse to save stack space */
193 /* qsort(pn - d2, d2 / es, es, cmp); */
199 /* Recurse on right partition, then iterate on left partition */
201 local_qsort(pn - d2, d2 / es, es, cmp, thunk);
204 /* Iterate rather than recurse to save stack space */
205 /* qsort(a, d1 / es, es, cmp); */
212 #if defined(I_AM_QSORT_R)
214 qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
216 local_qsort_r(a, n, es, cmp, thunk);
218 #elif defined(I_AM_QSORT_S)
220 qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk)
223 __throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL);
225 } else if (es > RSIZE_MAX) {
226 __throw_constraint_handler_s("qsort_s : es > RSIZE_MAX",
231 __throw_constraint_handler_s("qsort_s : a == NULL",
234 } else if (cmp == NULL) {
235 __throw_constraint_handler_s("qsort_s : cmp == NULL",
241 local_qsort_s(a, n, es, cmp, thunk);
246 qsort(void *a, size_t n, size_t es, cmp_t *cmp)
248 local_qsort(a, n, es, cmp, NULL);