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. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)radixsort.c 8.2 (Berkeley) 4/28/95 33 * $FreeBSD: src/lib/libc/stdlib/radixsort.c,v 1.8 2007/01/09 00:28:10 imp Exp $ 34 * $DragonFly: src/lib/libc/stdlib/radixsort.c,v 1.5 2005/11/20 12:37:49 swildner Exp $ 35 */ 36 37 /* 38 * Radixsort routines. 39 * 40 * Program r_sort_a() is unstable but uses O(logN) extra memory for a stack. 41 * Use radixsort(a, n, trace, endchar) for this case. 42 * 43 * For stable sorting (using N extra pointers) use sradixsort(), which calls 44 * r_sort_b(). 45 * 46 * For a description of this code, see D. McIlroy, P. McIlroy, K. Bostic, 47 * "Engineering Radix Sort". 48 */ 49 50 #include <sys/types.h> 51 #include <stdlib.h> 52 #include <stddef.h> 53 #include <errno.h> 54 55 typedef struct { 56 const u_char **sa; 57 int sn, si; 58 } stack; 59 60 static inline void simplesort(const u_char **, int, int, const u_char *, u_int); 61 static void r_sort_a(const u_char **, int, int, const u_char *, u_int); 62 static void r_sort_b(const u_char **, const u_char **, int, int, 63 const u_char *, u_int); 64 65 #define THRESHOLD 20 /* Divert to simplesort(). */ 66 #define SIZE 512 /* Default stack size. */ 67 68 #define SETUP { \ 69 if (tab == NULL) { \ 70 tr = tr0; \ 71 for (c = 0; c < endch; c++) \ 72 tr0[c] = c + 1; \ 73 tr0[c] = 0; \ 74 for (c++; c < 256; c++) \ 75 tr0[c] = c; \ 76 endch = 0; \ 77 } else { \ 78 endch = tab[endch]; \ 79 tr = tab; \ 80 if (endch != 0 && endch != 255) { \ 81 errno = EINVAL; \ 82 return (-1); \ 83 } \ 84 } \ 85 } 86 87 int 88 radixsort(const u_char **a, int n, const u_char *tab, u_int endch) 89 { 90 const u_char *tr; 91 int c; 92 u_char tr0[256]; 93 94 SETUP; 95 r_sort_a(a, n, 0, tr, endch); 96 return (0); 97 } 98 99 int 100 sradixsort(const u_char **a, int n, const u_char *tab, u_int endch) 101 { 102 const u_char *tr, **ta; 103 int c; 104 u_char tr0[256]; 105 106 SETUP; 107 if (n < THRESHOLD) 108 simplesort(a, n, 0, tr, endch); 109 else { 110 if ((ta = malloc(n * sizeof(a))) == NULL) 111 return (-1); 112 r_sort_b(a, ta, n, 0, tr, endch); 113 free(ta); 114 } 115 return (0); 116 } 117 118 #define empty(s) (s >= sp) 119 #define pop(a, n, i) a = (--sp)->sa, n = sp->sn, i = sp->si 120 #define push(a, n, i) sp->sa = a, sp->sn = n, (sp++)->si = i 121 #define swap(a, b, t) t = a, a = b, b = t 122 123 /* Unstable, in-place sort. */ 124 static void 125 r_sort_a(const u_char **a, int n, int i, const u_char *tr, u_int endch) 126 { 127 static int count[256], nc, bmin; 128 int c; 129 const u_char **ak, *r; 130 stack s[SIZE], *sp, *sp0, *sp1, temp; 131 int *cp, bigc; 132 const u_char **an, *t, **aj, **top[256]; 133 134 /* Set up stack. */ 135 sp = s; 136 push(a, n, i); 137 while (!empty(s)) { 138 pop(a, n, i); 139 if (n < THRESHOLD) { 140 simplesort(a, n, i, tr, endch); 141 continue; 142 } 143 an = a + n; 144 145 /* Make character histogram. */ 146 if (nc == 0) { 147 bmin = 255; /* First occupied bin, excluding eos. */ 148 for (ak = a; ak < an;) { 149 c = tr[(*ak++)[i]]; 150 if (++count[c] == 1 && c != endch) { 151 if (c < bmin) 152 bmin = c; 153 nc++; 154 } 155 } 156 if (sp + nc > s + SIZE) { /* Get more stack. */ 157 r_sort_a(a, n, i, tr, endch); 158 continue; 159 } 160 } 161 162 /* 163 * Special case: if all strings have the same 164 * character at position i, move on to the next 165 * character. 166 */ 167 if (nc == 1 && count[bmin] == n) { 168 push(a, n, i+1); 169 nc = count[bmin] = 0; 170 continue; 171 } 172 173 /* 174 * Set top[]; push incompletely sorted bins onto stack. 175 * top[] = pointers to last out-of-place element in bins. 176 * count[] = counts of elements in bins. 177 * Before permuting: top[c-1] + count[c] = top[c]; 178 * during deal: top[c] counts down to top[c-1]. 179 */ 180 sp0 = sp1 = sp; /* Stack position of biggest bin. */ 181 bigc = 2; /* Size of biggest bin. */ 182 if (endch == 0) /* Special case: set top[eos]. */ 183 top[0] = ak = a + count[0]; 184 else { 185 ak = a; 186 top[255] = an; 187 } 188 for (cp = count + bmin; nc > 0; cp++) { 189 while (*cp == 0) /* Find next non-empty pile. */ 190 cp++; 191 if (*cp > 1) { 192 if (*cp > bigc) { 193 bigc = *cp; 194 sp1 = sp; 195 } 196 push(ak, *cp, i+1); 197 } 198 top[cp-count] = ak += *cp; 199 nc--; 200 } 201 swap(*sp0, *sp1, temp); /* Play it safe -- biggest bin last. */ 202 203 /* 204 * Permute misplacements home. Already home: everything 205 * before aj, and in bin[c], items from top[c] on. 206 * Inner loop: 207 * r = next element to put in place; 208 * ak = top[r[i]] = location to put the next element. 209 * aj = bottom of 1st disordered bin. 210 * Outer loop: 211 * Once the 1st disordered bin is done, ie. aj >= ak, 212 * aj<-aj + count[c] connects the bins in a linked list; 213 * reset count[c]. 214 */ 215 for (aj = a; aj < an; *aj = r, aj += count[c], count[c] = 0) 216 for (r = *aj; aj < (ak = --top[c = tr[r[i]]]);) 217 swap(*ak, r, t); 218 } 219 } 220 221 /* Stable sort, requiring additional memory. */ 222 static void 223 r_sort_b(const u_char **a, const u_char **ta, int n, int i, const u_char *tr, 224 u_int endch) 225 { 226 static int count[256], nc, bmin; 227 int c; 228 const u_char **ak, **ai; 229 stack s[512], *sp, *sp0, *sp1, temp; 230 const u_char **top[256]; 231 int *cp, bigc; 232 233 sp = s; 234 push(a, n, i); 235 while (!empty(s)) { 236 pop(a, n, i); 237 if (n < THRESHOLD) { 238 simplesort(a, n, i, tr, endch); 239 continue; 240 } 241 242 if (nc == 0) { 243 bmin = 255; 244 for (ak = a + n; --ak >= a;) { 245 c = tr[(*ak)[i]]; 246 if (++count[c] == 1 && c != endch) { 247 if (c < bmin) 248 bmin = c; 249 nc++; 250 } 251 } 252 if (sp + nc > s + SIZE) { 253 r_sort_b(a, ta, n, i, tr, endch); 254 continue; 255 } 256 } 257 258 sp0 = sp1 = sp; 259 bigc = 2; 260 if (endch == 0) { 261 top[0] = ak = a + count[0]; 262 count[0] = 0; 263 } else { 264 ak = a; 265 top[255] = a + n; 266 count[255] = 0; 267 } 268 for (cp = count + bmin; nc > 0; cp++) { 269 while (*cp == 0) 270 cp++; 271 if ((c = *cp) > 1) { 272 if (c > bigc) { 273 bigc = c; 274 sp1 = sp; 275 } 276 push(ak, c, i+1); 277 } 278 top[cp-count] = ak += c; 279 *cp = 0; /* Reset count[]. */ 280 nc--; 281 } 282 swap(*sp0, *sp1, temp); 283 284 for (ak = ta + n, ai = a+n; ak > ta;) /* Copy to temp. */ 285 *--ak = *--ai; 286 for (ak = ta+n; --ak >= ta;) /* Deal to piles. */ 287 *--top[tr[(*ak)[i]]] = *ak; 288 } 289 } 290 291 /* insertion sort */ 292 static inline void 293 simplesort(const u_char **a, int n, int b, const u_char *tr, u_int endch) 294 { 295 u_char ch; 296 const u_char **ak, **ai, *s, *t; 297 298 for (ak = a+1; --n >= 1; ak++) 299 for (ai = ak; ai > a; ai--) { 300 for (s = ai[0] + b, t = ai[-1] + b; 301 (ch = tr[*s]) != endch; s++, t++) 302 if (ch != tr[*t]) 303 break; 304 if (ch >= tr[*t]) 305 break; 306 swap(ai[0], ai[-1], s); 307 } 308 } 309