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33 * $FreeBSD: src/sys/libkern/qsort.c,v 1.10 1999/08/28 00:46:35 peter Exp $
36 #include <sys/libkern.h>
38 typedef int cmp_t __P((const void *, const void *));
39 static __inline char *med3 __P((char *, char *, char *, cmp_t *));
40 static __inline void swapfunc __P((char *, char *, int, int));
42 #define min(a, b) (a) < (b) ? a : b
45 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
47 #define swapcode(TYPE, parmi, parmj, n) { \
48 long i = (n) / sizeof (TYPE); \
49 register TYPE *pi = (TYPE *) (parmi); \
50 register TYPE *pj = (TYPE *) (parmj); \
52 register TYPE t = *pi; \
58 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
59 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
62 swapfunc(a, b, n, swaptype)
67 swapcode(long, a, b, n)
69 swapcode(char, a, b, n)
73 if (swaptype == 0) { \
74 long t = *(long *)(a); \
75 *(long *)(a) = *(long *)(b); \
78 swapfunc(a, b, es, swaptype)
80 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
82 static __inline char *
87 return cmp(a, b) < 0 ?
88 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
89 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
98 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
99 int d, r, swaptype, swap_cnt;
101 loop: SWAPINIT(a, es);
104 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
105 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0;
110 pm = (char *)a + (n / 2) * es;
113 pn = (char *)a + (n - 1) * es;
116 pl = med3(pl, pl + d, pl + 2 * d, cmp);
117 pm = med3(pm - d, pm, pm + d, cmp);
118 pn = med3(pn - 2 * d, pn - d, pn, cmp);
120 pm = med3(pl, pm, pn, cmp);
123 pa = pb = (char *)a + es;
125 pc = pd = (char *)a + (n - 1) * es;
127 while (pb <= pc && (r = cmp(pb, a)) <= 0) {
135 while (pb <= pc && (r = cmp(pc, a)) >= 0) {
150 if (swap_cnt == 0) { /* Switch to insertion sort */
151 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
152 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0;
158 pn = (char *)a + n * es;
159 r = min(pa - (char *)a, pb - pa);
160 vecswap(a, pb - r, r);
161 r = min(pd - pc, pn - pd - es);
162 vecswap(pb, pn - r, r);
163 if ((r = pb - pa) > es)
164 qsort(a, r / es, es, cmp);
165 if ((r = pd - pc) > es) {
166 /* Iterate rather than recurse to save stack space */
171 /* qsort(pn - r, r / es, es, cmp);*/