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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)
38static char *rcsid = "$OpenBSD: radixsort.c,v 1.3 1996/08/19 08:33:44 tholo Exp $";
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
58typedef struct {
59 const u_char **sa;
60 int sn, si;
61} stack;
62
63static __inline void simplesort
64 __P((const u_char **, int, int, const u_char *, u_int));
65static void r_sort_a __P((const u_char **, int, int, const u_char *, u_int));
66static void r_sort_b __P((const u_char **,
67 const u_char **, int, int, const u_char *, 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 errno = EINVAL; \
86 return (-1); \
87 } \
88 } \
89}
90
91int
92radixsort(a, n, tab, endch)
93 const u_char **a, *tab;
94 int n;
95 u_int endch;
96{
97 const u_char *tr;
98 int c;
99 u_char tr0[256];
100
101 SETUP;
102 r_sort_a(a, n, 0, tr, endch);
103 return (0);
104}
105
106int
107sradixsort(a, n, tab, endch)
108 const u_char **a, *tab;
109 int n;
110 u_int endch;
111{
112 const u_char *tr, **ta;
113 int c;
114 u_char tr0[256];
115
116 SETUP;
117 if (n < THRESHOLD)
118 simplesort(a, n, 0, tr, endch);
119 else {
120 if ((ta = malloc(n * sizeof(a))) == NULL)
121 return (-1);
122 r_sort_b(a, ta, n, 0, tr, endch);
123 free(ta);
124 }
125 return (0);
126}
127
128#define empty(s) (s >= sp)
129#define pop(a, n, i) a = (--sp)->sa, n = sp->sn, i = sp->si
130#define push(a, n, i) sp->sa = a, sp->sn = n, (sp++)->si = i
131#define swap(a, b, t) t = a, a = b, b = t
132
133/* Unstable, in-place sort. */
134void
135r_sort_a(a, n, i, tr, endch)
136 const u_char **a;
137 int n, i;
138 const u_char *tr;
139 u_int endch;
140{
141 static int count[256], nc, bmin;
142 register int c;
143 register const u_char **ak, *r;
144 stack s[SIZE], *sp, *sp0, *sp1, temp;
145 int *cp, bigc;
146 const u_char **an, *t, **aj, **top[256];
147
148 /* Set up stack. */
149 sp = s;
150 push(a, n, i);
151 while (!empty(s)) {
152 pop(a, n, i);
153 if (n < THRESHOLD) {
154 simplesort(a, n, i, tr, endch);
155 continue;
156 }
157 an = a + n;
158
159 /* Make character histogram. */
160 if (nc == 0) {
161 bmin = 255; /* First occupied bin, excluding eos. */
162 for (ak = a; ak < an;) {
163 c = tr[(*ak++)[i]];
164 if (++count[c] == 1 && c != endch) {
165 if (c < bmin)
166 bmin = c;
167 nc++;
168 }
169 }
170 if (sp + nc > s + SIZE) { /* Get more stack. */
171 r_sort_a(a, n, i, tr, endch);
172 continue;
173 }
174 }
175
176 /*
177 * Set top[]; push incompletely sorted bins onto stack.
178 * top[] = pointers to last out-of-place element in bins.
179 * count[] = counts of elements in bins.
180 * Before permuting: top[c-1] + count[c] = top[c];
181 * during deal: top[c] counts down to top[c-1].
182 */
183 sp0 = sp1 = sp; /* Stack position of biggest bin. */
184 bigc = 2; /* Size of biggest bin. */
185 if (endch == 0) /* Special case: set top[eos]. */
186 top[0] = ak = a + count[0];
187 else {
188 ak = a;
189 top[255] = an;
190 }
191 for (cp = count + bmin; nc > 0; cp++) {
192 while (*cp == 0) /* Find next non-empty pile. */
193 cp++;
194 if (*cp > 1) {
195 if (*cp > bigc) {
196 bigc = *cp;
197 sp1 = sp;
198 }
199 push(ak, *cp, i+1);
200 }
201 top[cp-count] = ak += *cp;
202 nc--;
203 }
204 swap(*sp0, *sp1, temp); /* Play it safe -- biggest bin last. */
205
206 /*
207 * Permute misplacements home. Already home: everything
208 * before aj, and in bin[c], items from top[c] on.
209 * Inner loop:
210 * r = next element to put in place;
211 * ak = top[r[i]] = location to put the next element.
212 * aj = bottom of 1st disordered bin.
213 * Outer loop:
214 * Once the 1st disordered bin is done, ie. aj >= ak,
215 * aj<-aj + count[c] connects the bins in a linked list;
216 * reset count[c].
217 */
218 for (aj = a; aj < an; *aj = r, aj += count[c], count[c] = 0)
219 for (r = *aj; aj < (ak = --top[c = tr[r[i]]]);)
220 swap(*ak, r, t);
221 }
222}
223
224/* Stable sort, requiring additional memory. */
225void
226r_sort_b(a, ta, n, i, tr, endch)
227 const u_char **a, **ta;
228 int n, i;
229 const u_char *tr;
230 u_int endch;
231{
232 static int count[256], nc, bmin;
233 register int c;
234 register const u_char **ak, **ai;
235 stack s[512], *sp, *sp0, *sp1, temp;
236 const u_char **top[256];
237 int *cp, bigc;
238
239 sp = s;
240 push(a, n, i);
241 while (!empty(s)) {
242 pop(a, n, i);
243 if (n < THRESHOLD) {
244 simplesort(a, n, i, tr, endch);
245 continue;
246 }
247
248 if (nc == 0) {
249 bmin = 255;
250 for (ak = a + n; --ak >= a;) {
251 c = tr[(*ak)[i]];
252 if (++count[c] == 1 && c != endch) {
253 if (c < bmin)
254 bmin = c;
255 nc++;
256 }
257 }
258 if (sp + nc > s + SIZE) {
259 r_sort_b(a, ta, n, i, tr, endch);
260 continue;
261 }
262 }
263
264 sp0 = sp1 = sp;
265 bigc = 2;
266 if (endch == 0) {
267 top[0] = ak = a + count[0];
268 count[0] = 0;
269 } else {
270 ak = a;
271 top[255] = a + n;
272 count[255] = 0;
273 }
274 for (cp = count + bmin; nc > 0; cp++) {
275 while (*cp == 0)
276 cp++;
277 if ((c = *cp) > 1) {
278 if (c > bigc) {
279 bigc = c;
280 sp1 = sp;
281 }
282 push(ak, c, i+1);
283 }
284 top[cp-count] = ak += c;
285 *cp = 0; /* Reset count[]. */
286 nc--;
287 }
288 swap(*sp0, *sp1, temp);
289
290 for (ak = ta + n, ai = a+n; ak > ta;) /* Copy to temp. */
291 *--ak = *--ai;
292 for (ak = ta+n; --ak >= ta;) /* Deal to piles. */
293 *--top[tr[(*ak)[i]]] = *ak;
294 }
295}
296
297static __inline void
298simplesort(a, n, b, tr, endch) /* insertion sort */
299 register const u_char **a;
300 int n, b;
301 register const u_char *tr;
302 u_int endch;
303{
304 register u_char ch;
305 const u_char **ak, **ai, *s, *t;
306
307 for (ak = a+1; --n >= 1; ak++)
308 for (ai = ak; ai > a; ai--) {
309 for (s = ai[0] + b, t = ai[-1] + b;
310 (ch = tr[*s]) != endch; s++, t++)
311 if (ch != tr[*t])
312 break;
313 if (ch >= tr[*t])
314 break;
315 swap(ai[0], ai[-1], s);
316 }
317}
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