1// SPDX-License-Identifier: BSD-3-Clause
2/*
3 * Copyright (c) 1992, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 */
6
7#include "yportenv.h"
8#include <sort.h>
9/* #include <linux/string.h> */
10
11/*
12 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
13 */
14#define swapcode(TYPE, parmi, parmj, n) do {		\
15	long i = (n) / sizeof(TYPE);			\
16	register TYPE *pi = (TYPE *) (parmi);		\
17	register TYPE *pj = (TYPE *) (parmj);		\
18	do {						\
19		register TYPE	t = *pi;		\
20		*pi++ = *pj;				\
21		*pj++ = t;				\
22	} while (--i > 0);				\
23} while (0)
24
25#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
26	es % sizeof(long) ? 2 : es == sizeof(long) ? 0 : 1;
27
28static inline void
29swapfunc(char *a, char *b, int n, int swaptype)
30{
31	if (swaptype <= 1)
32		swapcode(long, a, b, n);
33	else
34		swapcode(char, a, b, n);
35}
36
37#define yswap(a, b) do {					\
38	if (swaptype == 0) {				\
39		long t = *(long *)(a);			\
40		*(long *)(a) = *(long *)(b);		\
41		*(long *)(b) = t;			\
42	} else						\
43		swapfunc(a, b, es, swaptype);		\
44} while (0)
45
46#define vecswap(a, b, n)	if ((n) > 0) swapfunc(a, b, n, swaptype)
47
48static inline char *
49med3(char *a, char *b, char *c, int (*cmp)(const void *, const void *))
50{
51	return cmp(a, b) < 0 ?
52		(cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a))
53		: (cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c));
54}
55
56#ifndef min
57#define min(a, b) (((a) < (b)) ? (a) : (b))
58#endif
59
60void
61yaffs_qsort(void *aa, size_t n, size_t es,
62	int (*cmp)(const void *, const void *))
63{
64	char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
65	int d, r, swaptype, swap_cnt;
66	register char *a = aa;
67
68loop:	SWAPINIT(a, es);
69	swap_cnt = 0;
70	if (n < 7) {
71		for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
72			for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
73			     pl -= es)
74				yswap(pl, pl - es);
75		return;
76	}
77	pm = (char *)a + (n / 2) * es;
78	if (n > 7) {
79		pl = (char *)a;
80		pn = (char *)a + (n - 1) * es;
81		if (n > 40) {
82			d = (n / 8) * es;
83			pl = med3(pl, pl + d, pl + 2 * d, cmp);
84			pm = med3(pm - d, pm, pm + d, cmp);
85			pn = med3(pn - 2 * d, pn - d, pn, cmp);
86		}
87		pm = med3(pl, pm, pn, cmp);
88	}
89	yswap(a, pm);
90	pa = pb = (char *)a + es;
91
92	pc = pd = (char *)a + (n - 1) * es;
93	for (;;) {
94		while (pb <= pc && (r = cmp(pb, a)) <= 0) {
95			if (r == 0) {
96				swap_cnt = 1;
97				yswap(pa, pb);
98				pa += es;
99			}
100			pb += es;
101		}
102		while (pb <= pc && (r = cmp(pc, a)) >= 0) {
103			if (r == 0) {
104				swap_cnt = 1;
105				yswap(pc, pd);
106				pd -= es;
107			}
108			pc -= es;
109		}
110		if (pb > pc)
111			break;
112		yswap(pb, pc);
113		swap_cnt = 1;
114		pb += es;
115		pc -= es;
116	}
117	if (swap_cnt == 0) {  /* Switch to insertion sort */
118		for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
119			for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
120			     pl -= es)
121				yswap(pl, pl - es);
122		return;
123	}
124
125	pn = (char *)a + n * es;
126	r = min(pa - (char *)a, pb - pa);
127	vecswap(a, pb - r, r);
128	r = min((long)(pd - pc), (long)(pn - pd - es));
129	vecswap(pb, pn - r, r);
130	r = pb - pa;
131	if (r > es)
132		yaffs_qsort(a, r / es, es, cmp);
133	r = pd - pc;
134	if (r > es) {
135		/* Iterate rather than recurse to save stack space */
136		a = pn - r;
137		n = r / es;
138		goto loop;
139	}
140/*		yaffs_qsort(pn - r, r / es, es, cmp);*/
141}
142