src/system/libroot/posix/stdlib/radixsort.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Peter McIlroy and by Dan Bernstein at New York University,
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 static char sccsid[] = "@(#)radixsort.c 8.2 (Berkeley) 4/28/95";
  39 #endif /* LIBC_SCCS and not lint */
  40
  41 /*
  42  * Radixsort routines.
  43  *
  44  * Program r_sort_a() is unstable but uses O(logN) extra memory for a stack.
  45  * Use radixsort(a, n, trace, endchar) for this case.
  46  *
  47  * For stable sorting (using N extra pointers) use sradixsort(), which calls
  48  * r_sort_b().
  49  *
  50  * For a description of this code, see D. McIlroy, P. McIlroy, K. Bostic,
  51  * "Engineering Radix Sort".
  52  */
  53
  54 #include <sys/types.h>
  55 #include <stdlib.h>
  56 #include <errno.h>
  57
  58 #include <errno_private.h>
  59
  60 typedef struct {
  61         const u_char **sa;
  62         int sn, si;
  63 } stack;
  64
  65 static inline void simplesort(u_char const **, int, int, u_char const *, u_int);
  66 static void r_sort_a(u_char const **, int, int, u_char const *, u_int);
  67 static void r_sort_b(u_char const **, u_char const **, int, int, u_char const *, u_int);
  68
  69 #define THRESHOLD       20              /* Divert to simplesort(). */
  70 #define SIZE            512             /* Default stack size. */
  71
  72 #define SETUP {                                                         \
  73         if (tab == NULL) {                                              \
  74                 tr = tr0;                                               \
  75                 for (c = 0; c < endch; c++)                             \
  76                         tr0[c] = c + 1;                                 \
  77                 tr0[c] = 0;                                             \
  78                 for (c++; c < 256; c++)                                 \
  79                         tr0[c] = c;                                     \
  80                 endch = 0;                                              \
  81         } else {                                                        \
  82                 endch = tab[endch];                                     \
  83                 tr = tab;                                               \
  84                 if (endch != 0 && endch != 255) {                       \
  85                         /* __set_errno(EINVAL); */                              \
  86                         return (-1);                                    \
  87                 }                                                       \
  88         }                                                               \
  89 }
  90
  91 int
  92 radixsort(u_char const **a, int n, u_char const *tab, u_int endch)
  93 {
  94         u_char const *tr;
  95         u_int c;
  96         u_char tr0[256];
  97
  98         SETUP;
  99         r_sort_a(a, n, 0, tr, endch);
 100         return (0);
 101 }
 102
 103 int
 104 sradixsort(u_char const **a, int n, u_char const *tab, u_int endch)
 105 {
 106         u_char const *tr;
 107         u_char const **ta;
 108         u_int c;
 109         u_char tr0[256];
 110
 111         SETUP;
 112         if (n < THRESHOLD)
 113                 simplesort(a, n, 0, tr, endch);
 114         else {
 115                 if ((ta = malloc(n * sizeof(a))) == NULL)
 116                         return (-1);
 117                 r_sort_b(a, ta, n, 0, tr, endch);
 118                 free(ta);
 119         }
 120         return (0);
 121 }
 122
 123 #define empty(s)        (s >= sp)
 124 #define pop(a, n, i)    a = (--sp)->sa, n = sp->sn, i = sp->si
 125 #define push(a, n, i)   sp->sa = a, sp->sn = n, (sp++)->si = i
 126 #define swap(a, b, t)   t = a, a = b, b = t
 127
 128 /* Unstable, in-place sort. */
 129 static void
 130 r_sort_a(u_char const **a, int n, int i, u_char const *tr, u_int endch)
 131 {
 132         static u_int count[256];
 133         static int  nc;
 134         static u_int  bmin;
 135         u_int c;
 136         u_char const **ak;
 137         u_char const *r;
 138         stack s[SIZE];
 139         stack *sp;
 140         stack *sp0;
 141         stack *sp1;
 142         stack temp;
 143         u_int *cp;
 144         u_int bigc;
 145         u_char const **an;
 146         u_char const *t;
 147         u_char const **aj;
 148         u_char const **top[256];
 149
 150         /* Set up stack. */
 151         sp = s;
 152         push(a, n, i);
 153         while (!empty(s)) {
 154                 pop(a, n, i);
 155                 if (n < THRESHOLD) {
 156                         simplesort(a, n, i, tr, endch);
 157                         continue;
 158                 }
 159                 an = a + n;
 160
 161                 /* Make character histogram. */
 162                 if (nc == 0) {
 163                         bmin = 255;     /* First occupied bin, excluding eos. */
 164                         for (ak = a; ak < an;) {
 165                                 c = tr[(*ak++)[i]];
 166                                 if (++count[c] == 1 && c != endch) {
 167                                         if (c < bmin)
 168                                                 bmin = c;
 169                                         nc++;
 170                                 }
 171                         }
 172                         if (sp + nc > s + SIZE) {       /* Get more stack. */
 173                                 r_sort_a(a, n, i, tr, endch);
 174                                 continue;
 175                         }
 176                 }
 177
 178                 /*
 179                  * Set top[]; push incompletely sorted bins onto stack.
 180                  * top[] = pointers to last out-of-place element in bins.
 181                  * count[] = counts of elements in bins.
 182                  * Before permuting: top[c-1] + count[c] = top[c];
 183                  * during deal: top[c] counts down to top[c-1].
 184                  */
 185                 sp0 = sp1 = sp;         /* Stack position of biggest bin. */
 186                 bigc = 2;               /* Size of biggest bin. */
 187                 if (endch == 0)         /* Special case: set top[eos]. */
 188                         top[0] = ak = a + count[0];
 189                 else {
 190                         ak = a;
 191                         top[255] = an;
 192                 }
 193                 for (cp = count + bmin; nc > 0; cp++) {
 194                         while (*cp == 0)        /* Find next non-empty pile. */
 195                                 cp++;
 196                         if (*cp > 1) {
 197                                 if (*cp > bigc) {
 198                                         bigc = *cp;
 199                                         sp1 = sp;
 200                                 }
 201                                 push(ak, *cp, i+1);
 202                         }
 203                         top[cp-count] = ak += *cp;
 204                         nc--;
 205                 }
 206                 swap(*sp0, *sp1, temp); /* Play it safe -- biggest bin last. */
 207
 208                 /*
 209                  * Permute misplacements home.  Already home: everything
 210                  * before aj, and in bin[c], items from top[c] on.
 211                  * Inner loop:
 212                  *      r = next element to put in place;
 213                  *      ak = top[r[i]] = location to put the next element.
 214                  *      aj = bottom of 1st disordered bin.
 215                  * Outer loop:
 216                  *      Once the 1st disordered bin is done, ie. aj >= ak,
 217                  *      aj<-aj + count[c] connects the bins in a linked list;
 218                  *      reset count[c].
 219                  */
 220                 for (aj = a; aj < an;  *aj = r, aj += count[c], count[c] = 0)
 221                         for (r = *aj;  aj < (ak = --top[c = tr[r[i]]]);)
 222                                 swap(*ak, r, t);
 223         }
 224 }
 225
 226 /* Stable sort, requiring additional memory. */
 227 static
 228 void
 229 r_sort_b(u_char const **a, u_char const **ta, int n, int i, u_char const *tr, u_int endch)
 230 {
 231         static int count[256];
 232         static u_int  nc;
 233         static u_int  bmin;
 234         u_int c;
 235         u_char const **ak, **ai;
 236         stack s[512], *sp, *sp0, *sp1, temp;
 237         u_char const **top[256];
 238         int *cp;
 239         u_int bigc;
 240
 241         sp = s;
 242         push(a, n, i);
 243         while (!empty(s)) {
 244                 pop(a, n, i);
 245                 if (n < THRESHOLD) {
 246                         simplesort(a, n, i, tr, endch);
 247                         continue;
 248                 }
 249
 250                 if (nc == 0) {
 251                         bmin = 255;
 252                         for (ak = a + n; --ak >= a;) {
 253                                 c = tr[(*ak)[i]];
 254                                 if (++count[c] == 1 && c != endch) {
 255                                         if (c < bmin)
 256                                                 bmin = c;
 257                                         nc++;
 258                                 }
 259                         }
 260                         if (sp + nc > s + SIZE) {
 261                                 r_sort_b(a, ta, n, i, tr, endch);
 262                                 continue;
 263                         }
 264                 }
 265
 266                 sp0 = sp1 = sp;
 267                 bigc = 2;
 268                 if (endch == 0) {
 269                         top[0] = ak = a + count[0];
 270                         count[0] = 0;
 271                 } else {
 272                         ak = a;
 273                         top[255] = a + n;
 274                         count[255] = 0;
 275                 }
 276                 for (cp = count + bmin; nc > 0; cp++) {
 277                         while (*cp == 0)
 278                                 cp++;
 279                         if ((c = *cp) > 1) {
 280                                 if (c > bigc) {
 281                                         bigc = c;
 282                                         sp1 = sp;
 283                                 }
 284                                 push(ak, c, i+1);
 285                         }
 286                         top[cp-count] = ak += c;
 287                         *cp = 0;                        /* Reset count[]. */
 288                         nc--;
 289                 }
 290                 swap(*sp0, *sp1, temp);
 291
 292                 for (ak = ta + n, ai = a+n; ak > ta;)   /* Copy to temp. */
 293                         *--ak = *--ai;
 294                 for (ak = ta+n; --ak >= ta;)            /* Deal to piles. */
 295                         *--top[tr[(*ak)[i]]] = *ak;
 296         }
 297 }
 298
 299 static inline
 300 void
 301 simplesort(u_char const **a, int n, int b, u_char const *tr, u_int endch)       /* insertion sort */
 302 {
 303         u_char ch;
 304         u_char const **ak;
 305         u_char const **ai;
 306         u_char const  *s;
 307         u_char const  *t;
 308
 309         for (ak = a+1; --n >= 1; ak++) {
 310                 for (ai = ak; ai > a; ai--) {
 311                         for (s = ai[0] + b, t = ai[-1] + b;
 312                             (ch = tr[*s]) != endch; s++, t++)
 313                                 if (ch != tr[*t])
 314                                         break;
 315                         if (ch >= tr[*t])
 316                                 break;
 317                         swap(ai[0], ai[-1], s);
 318                 }
 319         }
 320 }