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 *);
46 static inline void swapfunc(char *, char *, size_t, int, int);
48 #define MIN(a, b) ((a) < (b) ? a : b)
51 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
53 #define swapcode(TYPE, parmi, parmj, n) { \
54 size_t i = (n) / sizeof (TYPE); \
55 TYPE *pi = (TYPE *) (parmi); \
56 TYPE *pj = (TYPE *) (parmj); \
64 #define SWAPINIT(TYPE, a, es) swaptype_ ## TYPE = \
65 ((char *)a - (char *)0) % sizeof(TYPE) || \
66 es % sizeof(TYPE) ? 2 : es == sizeof(TYPE) ? 0 : 1;
69 swapfunc(char *a, char *b, size_t n, int swaptype_long, int swaptype_int)
71 if (swaptype_long <= 1)
72 swapcode(long, a, b, n)
73 else if (swaptype_int <= 1)
74 swapcode(int, a, b, n)
76 swapcode(char, a, b, n)
80 if (swaptype_long == 0) { \
81 long t = *(long *)(a); \
82 *(long *)(a) = *(long *)(b); \
84 } else if (swaptype_int == 0) { \
85 int t = *(int *)(a); \
86 *(int *)(a) = *(int *)(b); \
89 swapfunc(a, b, es, swaptype_long, swaptype_int)
91 #define vecswap(a, b, n) \
92 if ((n) > 0) swapfunc(a, b, n, swaptype_long, swaptype_int)
95 #define CMP(t, x, y) (cmp((t), (x), (y)))
97 #define CMP(t, x, y) (cmp((x), (y)))
101 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk
107 return CMP(thunk, a, b) < 0 ?
108 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a ))
109 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
114 qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
118 qsort(void *a, size_t n, size_t es, cmp_t *cmp)
121 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
124 int swaptype_long, swaptype_int, swap_cnt;
126 loop: SWAPINIT(long, a, es);
127 SWAPINIT(int, a, es);
130 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
132 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
137 pm = (char *)a + (n / 2) * es;
140 pn = (char *)a + (n - 1) * es;
142 size_t d = (n / 8) * es;
144 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
145 pm = med3(pm - d, pm, pm + d, cmp, thunk);
146 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
148 pm = med3(pl, pm, pn, cmp, thunk);
151 pa = pb = (char *)a + es;
153 pc = pd = (char *)a + (n - 1) * es;
155 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
156 if (cmp_result == 0) {
163 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
164 if (cmp_result == 0) {
178 if (swap_cnt == 0) { /* Switch to insertion sort */
179 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
181 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
187 pn = (char *)a + n * es;
188 d1 = MIN(pa - (char *)a, pb - pa);
189 vecswap(a, pb - d1, d1);
190 d1 = MIN(pd - pc, pn - pd - es);
191 vecswap(pb, pn - d1, d1);
196 /* Recurse on left partition, then iterate on right partition */
199 qsort_r(a, d1 / es, es, thunk, cmp);
201 qsort(a, d1 / es, es, cmp);
205 /* Iterate rather than recurse to save stack space */
206 /* qsort(pn - d2, d2 / es, es, cmp); */
212 /* Recurse on right partition, then iterate on left partition */
215 qsort_r(pn - d2, d2 / es, es, thunk, cmp);
217 qsort(pn - d2, d2 / es, es, cmp);
221 /* Iterate rather than recurse to save stack space */
222 /* qsort(a, d1 / es, es, cmp); */