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33 * @(#)qsort.c 8.1 (Berkeley) 6/4/93
34 * $FreeBSD: src/lib/libc/stdlib/qsort.c,v 1.8 1999/08/28 00:01:35 peter Exp $
35 * $DragonFly: src/lib/libc/stdlib/qsort.c,v 1.4 2003/09/06 08:19:16 asmodai Exp $
40 typedef int cmp_t (const void *, const void *);
41 static inline char *med3 (char *, char *, char *, cmp_t *);
42 static inline void swapfunc (char *, char *, int, int);
44 #define min(a, b) (a) < (b) ? a : b
47 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
49 #define swapcode(TYPE, parmi, parmj, n) { \
50 long i = (n) / sizeof (TYPE); \
51 TYPE *pi = (TYPE *) (parmi); \
52 TYPE *pj = (TYPE *) (parmj); \
60 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
61 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
64 swapfunc(a, b, n, swaptype)
69 swapcode(long, a, b, n)
71 swapcode(char, a, b, n)
75 if (swaptype == 0) { \
76 long t = *(long *)(a); \
77 *(long *)(a) = *(long *)(b); \
80 swapfunc(a, b, es, swaptype)
82 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
89 return cmp(a, b) < 0 ?
90 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
91 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
100 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
101 int d, r, swaptype, swap_cnt;
103 loop: SWAPINIT(a, es);
106 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
107 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0;
112 pm = (char *)a + (n / 2) * es;
115 pn = (char *)a + (n - 1) * es;
118 pl = med3(pl, pl + d, pl + 2 * d, cmp);
119 pm = med3(pm - d, pm, pm + d, cmp);
120 pn = med3(pn - 2 * d, pn - d, pn, cmp);
122 pm = med3(pl, pm, pn, cmp);
125 pa = pb = (char *)a + es;
127 pc = pd = (char *)a + (n - 1) * es;
129 while (pb <= pc && (r = cmp(pb, a)) <= 0) {
137 while (pb <= pc && (r = cmp(pc, a)) >= 0) {
152 if (swap_cnt == 0) { /* Switch to insertion sort */
153 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
154 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0;
160 pn = (char *)a + n * es;
161 r = min(pa - (char *)a, pb - pa);
162 vecswap(a, pb - r, r);
163 r = min(pd - pc, pn - pd - es);
164 vecswap(pb, pn - r, r);
165 if ((r = pb - pa) > es)
166 qsort(a, r / es, es, cmp);
167 if ((r = pd - pc) > es) {
168 /* Iterate rather than recurse to save stack space */
173 /* qsort(pn - r, r / es, es, cmp);*/