kernel26-2.6.12-alx-r9/lib/sort.c

/*
 * A fast, small, non-recursive O(nlog n) sort for the Linux kernel
 *
 * Jan 23 2005  Matt Mackall <mpm@selenic.com>
 */

#include <linux/kernel.h>
#include <linux/module.h>

void u32_swap(void *a, void *b, int size)
{
	u32 t = *(u32 *)a;
	*(u32 *)a = *(u32 *)b;
	*(u32 *)b = t;
}

void generic_swap(void *a, void *b, int size)
{
	char t;

	do {
		t = *(char *)a;
		*(char *)a++ = *(char *)b;
		*(char *)b++ = t;
	} while (--size > 0);
}

/*
 * sort - sort an array of elements
 * @base: pointer to data to sort
 * @num: number of elements
 * @size: size of each element
 * @cmp: pointer to comparison function
 * @swap: pointer to swap function or NULL
 *
 * This function does a heapsort on the given array. You may provide a
 * swap function optimized to your element type.
 *
 * Sorting time is O(n log n) both on average and worst-case. While
 * qsort is about 20% faster on average, it suffers from exploitable
 * O(n*n) worst-case behavior and extra memory requirements that make
 * it less suitable for kernel use.
 */

void sort(void *base, size_t num, size_t size,
	  int (*cmp)(const void *, const void *),
	  void (*swap)(void *, void *, int size))
{
	/* pre-scale counters for performance */
	int i = (num/2) * size, n = num * size, c, r;

	if (!swap)
		swap = (size == 4 ? u32_swap : generic_swap);

	/* heapify */
	for ( ; i >= 0; i -= size) {
		for (r = i; r * 2 < n; r  = c) {
			c = r * 2;
			if (c < n - size && cmp(base + c, base + c + size) < 0)
				c += size;
			if (cmp(base + r, base + c) >= 0)
				break;
			swap(base + r, base + c, size);
		}
	}

	/* sort */
	for (i = n - size; i >= 0; i -= size) {
		swap(base, base + i, size);
		for (r = 0; r * 2 < i; r = c) {
			c = r * 2;
			if (c < i - size && cmp(base + c, base + c + size) < 0)
				c += size;
			if (cmp(base + r, base + c) >= 0)
				break;
			swap(base + r, base + c, size);
		}
	}
}

EXPORT_SYMBOL(sort);

#if 0
/* a simple boot-time regression test */

int cmpint(const void *a, const void *b)
{
	return *(int *)a - *(int *)b;
}

static int sort_test(void)
{
	int *a, i, r = 1;

	a = kmalloc(1000 * sizeof(int), GFP_KERNEL);
	BUG_ON(!a);

	printk("testing sort()\n");

	for (i = 0; i < 1000; i++) {
		r = (r * 725861) % 6599;
		a[i] = r;
	}

	sort(a, 1000, sizeof(int), cmpint, NULL);

	for (i = 0; i < 999; i++)
		if (a[i] > a[i+1]) {
			printk("sort() failed!\n");
			break;
		}

	kfree(a);

	return 0;
}

module_init(sort_test);
#endif
1	/*
2	* A fast, small, non-recursive O(nlog n) sort for the Linux kernel
3	*
4	* Jan 23 2005 Matt Mackall <mpm@selenic.com>
5	*/
6
7	#include <linux/kernel.h>
8	#include <linux/module.h>
9
10	void u32_swap(void a, void b, int size)
11	{
12	u32 t = (u32 )a;
13	(u32 )a = (u32 )b;
14	(u32 )b = t;
15	}
16
17	void generic_swap(void a, void b, int size)
18	{
19	char t;
20
21	do {
22	t = (char )a;
23	(char )a++ = (char )b;
24	(char )b++ = t;
25	} while (--size > 0);
26	}
27
28	/*
29	* sort - sort an array of elements
30	* @base: pointer to data to sort
31	* @num: number of elements
32	* @size: size of each element
33	* @cmp: pointer to comparison function
34	* @swap: pointer to swap function or NULL
35	*
36	* This function does a heapsort on the given array. You may provide a
37	* swap function optimized to your element type.
38	*
39	* Sorting time is O(n log n) both on average and worst-case. While
40	* qsort is about 20% faster on average, it suffers from exploitable
41	* O(n*n) worst-case behavior and extra memory requirements that make
42	* it less suitable for kernel use.
43	*/
44
45	void sort(void *base, size_t num, size_t size,
46	int (cmp)(const void , const void *),
47	void (swap)(void , void *, int size))
48	{
49	/* pre-scale counters for performance */
50	int i = (num/2) * size, n = num * size, c, r;
51
52	if (!swap)
53	swap = (size == 4 ? u32_swap : generic_swap);
54
55	/* heapify */
56	for ( ; i >= 0; i -= size) {
57	for (r = i; r * 2 < n; r = c) {
58	c = r * 2;
59	if (c < n - size && cmp(base + c, base + c + size) < 0)
60	c += size;
61	if (cmp(base + r, base + c) >= 0)
62	break;
63	swap(base + r, base + c, size);
64	}
65	}
66
67	/* sort */
68	for (i = n - size; i >= 0; i -= size) {
69	swap(base, base + i, size);
70	for (r = 0; r * 2 < i; r = c) {
71	c = r * 2;
72	if (c < i - size && cmp(base + c, base + c + size) < 0)
73	c += size;
74	if (cmp(base + r, base + c) >= 0)
75	break;
76	swap(base + r, base + c, size);
77	}
78	}
79	}
80
81	EXPORT_SYMBOL(sort);
82
83	#if 0
84	/* a simple boot-time regression test */
85
86	int cmpint(const void a, const void b)
87	{
88	return (int )a - (int )b;
89	}
90
91	static int sort_test(void)
92	{
93	int *a, i, r = 1;
94
95	a = kmalloc(1000 * sizeof(int), GFP_KERNEL);
96	BUG_ON(!a);
97
98	printk("testing sort()\n");
99
100	for (i = 0; i < 1000; i++) {
101	r = (r * 725861) % 6599;
102	a[i] = r;
103	}
104
105	sort(a, 1000, sizeof(int), cmpint, NULL);
106
107	for (i = 0; i < 999; i++)
108	if (a[i] > a[i+1]) {
109	printk("sort() failed!\n");
110	break;
111	}
112
113	kfree(a);
114
115	return 0;
116	}
117
118	module_init(sort_test);
119	#endif