2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * Peter McIlroy and by Dan Bernstein at New York University,
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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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
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36 * $DragonFly: src/lib/libc/stdlib/radixsort.c,v 1.5 2005/11/20 12:37:49 swildner Exp $
38 * @(#)radixsort.c 8.2 (Berkeley) 4/28/95
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.
47 * For stable sorting (using N extra pointers) use sradixsort(), which calls
50 * For a description of this code, see D. McIlroy, P. McIlroy, K. Bostic,
51 * "Engineering Radix Sort".
54 #include <sys/types.h>
64 static inline void simplesort
65 (const u_char **, int, int, const u_char *, u_int);
66 static void r_sort_a (const u_char **, int, int, const u_char *, u_int);
67 static void r_sort_b (const u_char **,
68 const u_char **, int, int, const u_char *, u_int);
70 #define THRESHOLD 20 /* Divert to simplesort(). */
71 #define SIZE 512 /* Default stack size. */
76 for (c = 0; c < endch; c++) \
79 for (c++; c < 256; c++) \
85 if (endch != 0 && endch != 255) { \
93 radixsort(const u_char **a, int n, const u_char *tab, u_int endch)
100 r_sort_a(a, n, 0, tr, endch);
105 sradixsort(const u_char **a, int n, const u_char *tab, u_int endch)
107 const u_char *tr, **ta;
113 simplesort(a, n, 0, tr, endch);
115 if ((ta = malloc(n * sizeof(a))) == NULL)
117 r_sort_b(a, ta, n, 0, tr, endch);
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
128 /* Unstable, in-place sort. */
130 r_sort_a(const u_char **a, int n, int i, const u_char *tr, u_int endch)
132 static int count[256], nc, bmin;
134 const u_char **ak, *r;
135 stack s[SIZE], *sp, *sp0, *sp1, temp;
137 const u_char **an, *t, **aj, **top[256];
145 simplesort(a, n, i, tr, endch);
150 /* Make character histogram. */
152 bmin = 255; /* First occupied bin, excluding eos. */
153 for (ak = a; ak < an;) {
155 if (++count[c] == 1 && c != endch) {
161 if (sp + nc > s + SIZE) { /* Get more stack. */
162 r_sort_a(a, n, i, tr, endch);
168 * Set top[]; push incompletely sorted bins onto stack.
169 * top[] = pointers to last out-of-place element in bins.
170 * count[] = counts of elements in bins.
171 * Before permuting: top[c-1] + count[c] = top[c];
172 * during deal: top[c] counts down to top[c-1].
174 sp0 = sp1 = sp; /* Stack position of biggest bin. */
175 bigc = 2; /* Size of biggest bin. */
176 if (endch == 0) /* Special case: set top[eos]. */
177 top[0] = ak = a + count[0];
182 for (cp = count + bmin; nc > 0; cp++) {
183 while (*cp == 0) /* Find next non-empty pile. */
192 top[cp-count] = ak += *cp;
195 swap(*sp0, *sp1, temp); /* Play it safe -- biggest bin last. */
198 * Permute misplacements home. Already home: everything
199 * before aj, and in bin[c], items from top[c] on.
201 * r = next element to put in place;
202 * ak = top[r[i]] = location to put the next element.
203 * aj = bottom of 1st disordered bin.
205 * Once the 1st disordered bin is done, ie. aj >= ak,
206 * aj<-aj + count[c] connects the bins in a linked list;
209 for (aj = a; aj < an; *aj = r, aj += count[c], count[c] = 0)
210 for (r = *aj; aj < (ak = --top[c = tr[r[i]]]);)
215 /* Stable sort, requiring additional memory. */
217 r_sort_b(const u_char **a, const u_char **ta, int n, int i, const u_char *tr,
220 static int count[256], nc, bmin;
222 const u_char **ak, **ai;
223 stack s[512], *sp, *sp0, *sp1, temp;
224 const u_char **top[256];
232 simplesort(a, n, i, tr, endch);
238 for (ak = a + n; --ak >= a;) {
240 if (++count[c] == 1 && c != endch) {
246 if (sp + nc > s + SIZE) {
247 r_sort_b(a, ta, n, i, tr, endch);
255 top[0] = ak = a + count[0];
262 for (cp = count + bmin; nc > 0; cp++) {
272 top[cp-count] = ak += c;
273 *cp = 0; /* Reset count[]. */
276 swap(*sp0, *sp1, temp);
278 for (ak = ta + n, ai = a+n; ak > ta;) /* Copy to temp. */
280 for (ak = ta+n; --ak >= ta;) /* Deal to piles. */
281 *--top[tr[(*ak)[i]]] = *ak;
287 simplesort(const u_char **a, int n, int b, const u_char *tr, u_int endch)
290 const u_char **ak, **ai, *s, *t;
292 for (ak = a+1; --n >= 1; ak++)
293 for (ai = ak; ai > a; ai--) {
294 for (s = ai[0] + b, t = ai[-1] + b;
295 (ch = tr[*s]) != endch; s++, t++)
300 swap(ai[0], ai[-1], s);