Merge branch 'master' of git://git.denx.de/u-boot-mpc85xx
[platform/kernel/u-boot.git] / lib / qsort.c
1 /*
2  * Code adapted from uClibc-0.9.30.3
3  *
4  * It is therefore covered by the GNU LESSER GENERAL PUBLIC LICENSE
5  * Version 2.1, February 1999
6  *
7  * Wolfgang Denk <wd@denx.de>
8  */
9
10 /* This code is derived from a public domain shell sort routine by
11  * Ray Gardner and found in Bob Stout's snippets collection.  The
12  * original code is included below in an #if 0/#endif block.
13  *
14  * I modified it to avoid the possibility of overflow in the wgap
15  * calculation, as well as to reduce the generated code size with
16  * bcc and gcc. */
17
18 #include <linux/types.h>
19 #include <exports.h>
20
21 void qsort(void  *base,
22            size_t nel,
23            size_t width,
24            int (*comp)(const void *, const void *))
25 {
26         size_t wgap, i, j, k;
27         char tmp;
28
29         if ((nel > 1) && (width > 0)) {
30                 assert(nel <= ((size_t)(-1)) / width); /* check for overflow */
31                 wgap = 0;
32                 do {
33                         wgap = 3 * wgap + 1;
34                 } while (wgap < (nel-1)/3);
35                 /* From the above, we know that either wgap == 1 < nel or */
36                 /* ((wgap-1)/3 < (int) ((nel-1)/3) <= (nel-1)/3 ==> wgap <  nel. */
37                 wgap *= width;                  /* So this can not overflow if wnel doesn't. */
38                 nel *= width;                   /* Convert nel to 'wnel' */
39                 do {
40                         i = wgap;
41                         do {
42                                 j = i;
43                                 do {
44                                         register char *a;
45                                         register char *b;
46
47                                         j -= wgap;
48                                         a = j + ((char *)base);
49                                         b = a + wgap;
50                                         if ((*comp)(a, b) <= 0) {
51                                                 break;
52                                         }
53                                         k = width;
54                                         do {
55                                                 tmp = *a;
56                                                 *a++ = *b;
57                                                 *b++ = tmp;
58                                         } while (--k);
59                                 } while (j >= wgap);
60                                 i += width;
61                         } while (i < nel);
62                         wgap = (wgap - width)/3;
63                 } while (wgap);
64         }
65 }
66
67 int strcmp_compar(const void *p1, const void *p2)
68 {
69         return strcmp(*(const char **)p1, *(const char **)p2);
70 }