uboot/fs/yaffs2/yaffs_qsort.c
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   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 <linux/string.h> */
   9
  10/*
  11 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
  12 */
  13#define swapcode(TYPE, parmi, parmj, n) do {            \
  14        long i = (n) / sizeof(TYPE);                    \
  15        register TYPE *pi = (TYPE *) (parmi);           \
  16        register TYPE *pj = (TYPE *) (parmj);           \
  17        do {                                            \
  18                register TYPE   t = *pi;                \
  19                *pi++ = *pj;                            \
  20                *pj++ = t;                              \
  21        } while (--i > 0);                              \
  22} while (0)
  23
  24#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
  25        es % sizeof(long) ? 2 : es == sizeof(long) ? 0 : 1;
  26
  27static inline void
  28swapfunc(char *a, char *b, int n, int swaptype)
  29{
  30        if (swaptype <= 1)
  31                swapcode(long, a, b, n);
  32        else
  33                swapcode(char, a, b, n);
  34}
  35
  36#define yswap(a, b) do {                                        \
  37        if (swaptype == 0) {                            \
  38                long t = *(long *)(a);                  \
  39                *(long *)(a) = *(long *)(b);            \
  40                *(long *)(b) = t;                       \
  41        } else                                          \
  42                swapfunc(a, b, es, swaptype);           \
  43} while (0)
  44
  45#define vecswap(a, b, n)        if ((n) > 0) swapfunc(a, b, n, swaptype)
  46
  47static inline char *
  48med3(char *a, char *b, char *c, int (*cmp)(const void *, const void *))
  49{
  50        return cmp(a, b) < 0 ?
  51                (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a))
  52                : (cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c));
  53}
  54
  55#ifndef min
  56#define min(a, b) (((a) < (b)) ? (a) : (b))
  57#endif
  58
  59void
  60yaffs_qsort(void *aa, size_t n, size_t es,
  61        int (*cmp)(const void *, const void *))
  62{
  63        char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
  64        int d, r, swaptype, swap_cnt;
  65        register char *a = aa;
  66
  67loop:   SWAPINIT(a, es);
  68        swap_cnt = 0;
  69        if (n < 7) {
  70                for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
  71                        for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
  72                             pl -= es)
  73                                yswap(pl, pl - es);
  74                return;
  75        }
  76        pm = (char *)a + (n / 2) * es;
  77        if (n > 7) {
  78                pl = (char *)a;
  79                pn = (char *)a + (n - 1) * es;
  80                if (n > 40) {
  81                        d = (n / 8) * es;
  82                        pl = med3(pl, pl + d, pl + 2 * d, cmp);
  83                        pm = med3(pm - d, pm, pm + d, cmp);
  84                        pn = med3(pn - 2 * d, pn - d, pn, cmp);
  85                }
  86                pm = med3(pl, pm, pn, cmp);
  87        }
  88        yswap(a, pm);
  89        pa = pb = (char *)a + es;
  90
  91        pc = pd = (char *)a + (n - 1) * es;
  92        for (;;) {
  93                while (pb <= pc && (r = cmp(pb, a)) <= 0) {
  94                        if (r == 0) {
  95                                swap_cnt = 1;
  96                                yswap(pa, pb);
  97                                pa += es;
  98                        }
  99                        pb += es;
 100                }
 101                while (pb <= pc && (r = cmp(pc, a)) >= 0) {
 102                        if (r == 0) {
 103                                swap_cnt = 1;
 104                                yswap(pc, pd);
 105                                pd -= es;
 106                        }
 107                        pc -= es;
 108                }
 109                if (pb > pc)
 110                        break;
 111                yswap(pb, pc);
 112                swap_cnt = 1;
 113                pb += es;
 114                pc -= es;
 115        }
 116        if (swap_cnt == 0) {  /* Switch to insertion sort */
 117                for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
 118                        for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
 119                             pl -= es)
 120                                yswap(pl, pl - es);
 121                return;
 122        }
 123
 124        pn = (char *)a + n * es;
 125        r = min(pa - (char *)a, pb - pa);
 126        vecswap(a, pb - r, r);
 127        r = min((long)(pd - pc), (long)(pn - pd - es));
 128        vecswap(pb, pn - r, r);
 129        r = pb - pa;
 130        if (r > es)
 131                yaffs_qsort(a, r / es, es, cmp);
 132        r = pd - pc;
 133        if (r > es) {
 134                /* Iterate rather than recurse to save stack space */
 135                a = pn - r;
 136                n = r / es;
 137                goto loop;
 138        }
 139/*              yaffs_qsort(pn - r, r / es, es, cmp);*/
 140}
 141