1 /* $NetBSD: radixsort.c,v 1.19 2009/09/05 08:53:06 dsl Exp $ */ 2 3 /*- 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Peter McIlroy and by Dan Bernstein at New York University, 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "@(#)radixsort.c 8.2 (Berkeley) 4/28/95"; 39 #else 40 __RCSID("$NetBSD: radixsort.c,v 1.19 2009/09/05 08:53:06 dsl Exp $"); 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 /* 45 * Radixsort routines. 46 * 47 * Program r_sort_a() is unstable but uses O(logN) extra memory for a stack. 48 * Use radixsort(a, n, trace, endchar) for this case. 49 * 50 * For stable sorting (using N extra pointers) use sradixsort(), which calls 51 * r_sort_b(). 52 * 53 * For a description of this code, see D. McIlroy, P. McIlroy, K. Bostic, 54 * "Engineering Radix Sort". 55 */ 56 57 #include "namespace.h" 58 #include <sys/types.h> 59 60 #include <assert.h> 61 #include <errno.h> 62 #include <stdlib.h> 63 64 #ifdef __weak_alias 65 __weak_alias(radixsort,_radixsort) 66 __weak_alias(sradixsort,_sradixsort) 67 #endif 68 69 typedef struct { 70 const u_char **sa; 71 int sn, si; 72 } stack; 73 74 static inline void simplesort(const u_char **, int, int, const u_char *, u_int); 75 static void r_sort_a(const u_char **, int, int, const u_char *, u_int); 76 static void r_sort_b(const u_char **, 77 const u_char **, int, int, const u_char *, u_int); 78 79 #define THRESHOLD 20 /* Divert to simplesort(). */ 80 #define SIZE 512 /* Default stack size. */ 81 82 #define SETUP { \ 83 if (tab == NULL) { \ 84 tr = tr0; \ 85 for (c = 0; c < endch; c++) \ 86 tr0[c] = c + 1; \ 87 tr0[c] = 0; \ 88 for (c++; c < 256; c++) \ 89 tr0[c] = c; \ 90 endch = 0; \ 91 } else { \ 92 endch = tab[endch]; \ 93 tr = tab; \ 94 if (endch != 0 && endch != 255) { \ 95 errno = EINVAL; \ 96 return (-1); \ 97 } \ 98 } \ 99 } 100 101 int 102 radixsort(const u_char **a, int n, const u_char *tab, u_int endch) 103 { 104 const u_char *tr; 105 u_int c; 106 u_char tr0[256]; 107 108 _DIAGASSERT(a != NULL); 109 110 SETUP; 111 r_sort_a(a, n, 0, tr, endch); 112 return (0); 113 } 114 115 int 116 sradixsort(const u_char **a, int n, const u_char *tab, u_int endch) 117 { 118 const u_char *tr, **ta; 119 u_int c; 120 u_char tr0[256]; 121 122 _DIAGASSERT(a != NULL); 123 if (a == NULL) { 124 errno = EFAULT; 125 return (-1); 126 } 127 128 SETUP; 129 if (n < THRESHOLD) 130 simplesort(a, n, 0, tr, endch); 131 else { 132 if ((ta = malloc(n * sizeof(a))) == NULL) 133 return (-1); 134 r_sort_b(a, ta, n, 0, tr, endch); 135 free(ta); 136 } 137 return (0); 138 } 139 140 #define empty(s) (s >= sp) 141 #define pop(a, n, i) a = (--sp)->sa, n = sp->sn, i = sp->si 142 #define push(a, n, i) sp->sa = a, sp->sn = n, (sp++)->si = i 143 #define swap(a, b, t) t = a, a = b, b = t 144 145 /* Unstable, in-place sort. */ 146 static void 147 r_sort_a(const u_char **a, int n, int i, const u_char *tr, u_int endch) 148 { 149 static u_int count[256], nc, bmin; 150 u_int c; 151 const u_char **ak, *r; 152 stack s[SIZE], *sp, *sp0, *sp1, temp; 153 u_int *cp, bigc; 154 const u_char **an, *t, **aj, **top[256]; 155 156 _DIAGASSERT(a != NULL); 157 _DIAGASSERT(tr != NULL); 158 159 /* Set up stack. */ 160 sp = s; 161 push(a, n, i); 162 while (!empty(s)) { 163 pop(a, n, i); 164 if (n < THRESHOLD) { 165 simplesort(a, n, i, tr, endch); 166 continue; 167 } 168 an = a + n; 169 170 /* Make character histogram. */ 171 if (nc == 0) { 172 bmin = 255; /* First occupied bin, excluding eos. */ 173 for (ak = a; ak < an;) { 174 c = tr[(*ak++)[i]]; 175 if (++count[c] == 1 && c != endch) { 176 if (c < bmin) 177 bmin = c; 178 nc++; 179 } 180 } 181 if (sp + nc > s + SIZE) { /* Get more stack. */ 182 r_sort_a(a, n, i, tr, endch); 183 continue; 184 } 185 } 186 187 /* 188 * Set top[]; push incompletely sorted bins onto stack. 189 * top[] = pointers to last out-of-place element in bins. 190 * count[] = counts of elements in bins. 191 * Before permuting: top[c-1] + count[c] = top[c]; 192 * during deal: top[c] counts down to top[c-1]. 193 */ 194 sp0 = sp1 = sp; /* Stack position of biggest bin. */ 195 bigc = 2; /* Size of biggest bin. */ 196 if (endch == 0) /* Special case: set top[eos]. */ 197 top[0] = ak = a + count[0]; 198 else { 199 ak = a; 200 top[255] = an; 201 } 202 for (cp = count + bmin; nc > 0; cp++) { 203 while (*cp == 0) /* Find next non-empty pile. */ 204 cp++; 205 if (*cp > 1) { 206 if (*cp > bigc) { 207 bigc = *cp; 208 sp1 = sp; 209 } 210 push(ak, *cp, i+1); 211 } 212 top[cp-count] = ak += *cp; 213 nc--; 214 } 215 swap(*sp0, *sp1, temp); /* Play it safe -- biggest bin last. */ 216 217 /* 218 * Permute misplacements home. Already home: everything 219 * before aj, and in bin[c], items from top[c] on. 220 * Inner loop: 221 * r = next element to put in place; 222 * ak = top[r[i]] = location to put the next element. 223 * aj = bottom of 1st disordered bin. 224 * Outer loop: 225 * Once the 1st disordered bin is done, ie. aj >= ak, 226 * aj<-aj + count[c] connects the bins in a linked list; 227 * reset count[c]. 228 */ 229 for (aj = a; aj < an; *aj = r, aj += count[c], count[c] = 0) 230 for (r = *aj; aj < (ak = --top[c = tr[r[i]]]);) 231 swap(*ak, r, t); 232 } 233 } 234 235 /* Stable sort, requiring additional memory. */ 236 static void 237 r_sort_b(const u_char **a, const u_char **ta, int n, int i, const u_char *tr, 238 u_int endch) 239 { 240 static u_int count[256], nc, bmin; 241 u_int c; 242 const u_char **ak, **ai; 243 stack s[512], *sp, *sp0, *sp1, temp; 244 const u_char **top[256]; 245 u_int *cp, bigc; 246 247 _DIAGASSERT(a != NULL); 248 _DIAGASSERT(ta != NULL); 249 _DIAGASSERT(tr != NULL); 250 251 sp = s; 252 push(a, n, i); 253 while (!empty(s)) { 254 pop(a, n, i); 255 if (n < THRESHOLD) { 256 simplesort(a, n, i, tr, endch); 257 continue; 258 } 259 260 if (nc == 0) { 261 bmin = 255; 262 for (ak = a + n; --ak >= a;) { 263 c = tr[(*ak)[i]]; 264 if (++count[c] == 1 && c != endch) { 265 if (c < bmin) 266 bmin = c; 267 nc++; 268 } 269 } 270 if (sp + nc > s + SIZE) { 271 r_sort_b(a, ta, n, i, tr, endch); 272 continue; 273 } 274 } 275 276 sp0 = sp1 = sp; 277 bigc = 2; 278 if (endch == 0) { 279 top[0] = ak = a + count[0]; 280 count[0] = 0; 281 } else { 282 ak = a; 283 top[255] = a + n; 284 count[255] = 0; 285 } 286 for (cp = count + bmin; nc > 0; cp++) { 287 while (*cp == 0) 288 cp++; 289 if ((c = *cp) > 1) { 290 if (c > bigc) { 291 bigc = c; 292 sp1 = sp; 293 } 294 push(ak, c, i+1); 295 } 296 top[cp-count] = ak += c; 297 *cp = 0; /* Reset count[]. */ 298 nc--; 299 } 300 swap(*sp0, *sp1, temp); 301 302 for (ak = ta + n, ai = a+n; ak > ta;) /* Copy to temp. */ 303 *--ak = *--ai; 304 for (ak = ta+n; --ak >= ta;) /* Deal to piles. */ 305 *--top[tr[(*ak)[i]]] = *ak; 306 } 307 } 308 309 /* insertion sort */ 310 static inline void 311 simplesort(const u_char **a, int n, int b, const u_char *tr, u_int endch) 312 { 313 u_char ch; 314 const u_char **ak, **ai, *s, *t; 315 316 _DIAGASSERT(a != NULL); 317 _DIAGASSERT(tr != NULL); 318 319 for (ak = a+1; --n >= 1; ak++) 320 for (ai = ak; ai > a; ai--) { 321 for (s = ai[0] + b, t = ai[-1] + b; 322 (ch = tr[*s]) != endch; s++, t++) 323 if (ch != tr[*t]) 324 break; 325 if (ch >= tr[*t]) 326 break; 327 swap(ai[0], ai[-1], s); 328 } 329 } 330