LXR uboot/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
  21void 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
  67int strcmp_compar(const void *p1, const void *p2)
  68{
  69        return strcmp(*(const char **)p1, *(const char **)p2);
  70}
  71