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 <common.h>
  20#include <exports.h>
  21
  22void qsort(void  *base,
  23           size_t nel,
  24           size_t width,
  25           int (*comp)(const void *, const void *))
  26{
  27        size_t wgap, i, j, k;
  28        char tmp;
  29
  30        if ((nel > 1) && (width > 0)) {
  31                assert(nel <= ((size_t)(-1)) / width); /* check for overflow */
  32                wgap = 0;
  33                do {
  34                        wgap = 3 * wgap + 1;
  35                } while (wgap < (nel-1)/3);
  36                /* From the above, we know that either wgap == 1 < nel or */
  37                /* ((wgap-1)/3 < (int) ((nel-1)/3) <= (nel-1)/3 ==> wgap <  nel. */
  38                wgap *= width;                  /* So this can not overflow if wnel doesn't. */
  39                nel *= width;                   /* Convert nel to 'wnel' */
  40                do {
  41                        i = wgap;
  42                        do {
  43                                j = i;
  44                                do {
  45                                        register char *a;
  46                                        register char *b;
  47
  48                                        j -= wgap;
  49                                        a = j + ((char *)base);
  50                                        b = a + wgap;
  51                                        if ((*comp)(a, b) <= 0) {
  52                                                break;
  53                                        }
  54                                        k = width;
  55                                        do {
  56                                                tmp = *a;
  57                                                *a++ = *b;
  58                                                *b++ = tmp;
  59                                        } while (--k);
  60                                } while (j >= wgap);
  61                                i += width;
  62                        } while (i < nel);
  63                        wgap = (wgap - width)/3;
  64                } while (wgap);
  65        }
  66}
  67
  68int strcmp_compar(const void *p1, const void *p2)
  69{
  70        return strcmp(*(const char **)p1, *(const char **)p2);
  71}
  72