1 /* $NetBSD: radixsort.c,v 1.22 2022/03/12 17:31:39 christos 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 1.22 2022/03/12 17:31:39 christos 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 ta = NULL; 133 errno = reallocarr(&ta, n, sizeof(*ta)); 134 if (errno) 135 return -1; 136 r_sort_b(a, ta, n, 0, tr, endch); 137 free(ta); 138 } 139 return (0); 140 } 141 142 #define empty(s) (s >= sp) 143 #define pop(a, n, i) a = (--sp)->sa, n = sp->sn, i = sp->si 144 #define push(a, n, i) sp->sa = a, sp->sn = n, (sp++)->si = i 145 #define swap(a, b, t) t = a, a = b, b = t 146 147 /* Unstable, in-place sort. */ 148 static void 149 r_sort_a(const u_char **a, int n, int i, const u_char *tr, u_int endch) 150 { 151 static u_int count[256], nc, bmin; 152 u_int c; 153 const u_char **ak, *r; 154 stack s[SIZE], *sp, *sp0, *sp1, temp; 155 u_int *cp, bigc; 156 const u_char **an, *t, **aj, **top[256]; 157 158 _DIAGASSERT(a != NULL); 159 _DIAGASSERT(tr != NULL); 160 161 /* Set up stack. */ 162 sp = s; 163 push(a, n, i); 164 while (!empty(s)) { 165 pop(a, n, i); 166 if (n < THRESHOLD) { 167 simplesort(a, n, i, tr, endch); 168 continue; 169 } 170 an = a + n; 171 172 /* Make character histogram. */ 173 if (nc == 0) { 174 bmin = 255; /* First occupied bin, excluding eos. */ 175 for (ak = a; ak < an;) { 176 c = tr[(*ak++)[i]]; 177 if (++count[c] == 1 && c != endch) { 178 if (c < bmin) 179 bmin = c; 180 nc++; 181 } 182 } 183 if (sp + nc > s + SIZE) { /* Get more stack. */ 184 r_sort_a(a, n, i, tr, endch); 185 continue; 186 } 187 } 188 189 /* 190 * Set top[]; push incompletely sorted bins onto stack. 191 * top[] = pointers to last out-of-place element in bins. 192 * count[] = counts of elements in bins. 193 * Before permuting: top[c-1] + count[c] = top[c]; 194 * during deal: top[c] counts down to top[c-1]. 195 */ 196 sp0 = sp1 = sp; /* Stack position of biggest bin. */ 197 bigc = 2; /* Size of biggest bin. */ 198 if (endch == 0) /* Special case: set top[eos]. */ 199 top[0] = ak = a + count[0]; 200 else { 201 ak = a; 202 top[255] = an; 203 } 204 for (cp = count + bmin; nc > 0; cp++) { 205 while (*cp == 0) /* Find next non-empty pile. */ 206 cp++; 207 if (*cp > 1) { 208 if (*cp > bigc) { 209 bigc = *cp; 210 sp1 = sp; 211 } 212 push(ak, *cp, i+1); 213 } 214 top[cp-count] = ak += *cp; 215 nc--; 216 } 217 swap(*sp0, *sp1, temp); /* Play it safe -- biggest bin last. */ 218 219 /* 220 * Permute misplacements home. Already home: everything 221 * before aj, and in bin[c], items from top[c] on. 222 * Inner loop: 223 * r = next element to put in place; 224 * ak = top[r[i]] = location to put the next element. 225 * aj = bottom of 1st disordered bin. 226 * Outer loop: 227 * Once the 1st disordered bin is done, ie. aj >= ak, 228 * aj<-aj + count[c] connects the bins in a linked list; 229 * reset count[c]. 230 */ 231 for (aj = a; aj < an; *aj = r, aj += count[c], count[c] = 0) 232 for (r = *aj; aj < (ak = --top[c = tr[r[i]]]);) 233 swap(*ak, r, t); 234 } 235 } 236 237 /* Stable sort, requiring additional memory. */ 238 static void 239 r_sort_b(const u_char **a, const u_char **ta, int n, int i, const u_char *tr, 240 u_int endch) 241 { 242 static u_int count[256], nc, bmin; 243 u_int c; 244 const u_char **ak, **ai; 245 stack s[512], *sp, *sp0, *sp1, temp; 246 const u_char **top[256]; 247 u_int *cp, bigc; 248 249 _DIAGASSERT(a != NULL); 250 _DIAGASSERT(ta != NULL); 251 _DIAGASSERT(tr != NULL); 252 253 sp = s; 254 push(a, n, i); 255 while (!empty(s)) { 256 pop(a, n, i); 257 if (n < THRESHOLD) { 258 simplesort(a, n, i, tr, endch); 259 continue; 260 } 261 262 if (nc == 0) { 263 bmin = 255; 264 for (ak = a + n; --ak >= a;) { 265 c = tr[(*ak)[i]]; 266 if (++count[c] == 1 && c != endch) { 267 if (c < bmin) 268 bmin = c; 269 nc++; 270 } 271 } 272 if (sp + nc > s + SIZE) { 273 r_sort_b(a, ta, n, i, tr, endch); 274 continue; 275 } 276 } 277 278 sp0 = sp1 = sp; 279 bigc = 2; 280 if (endch == 0) { 281 top[0] = ak = a + count[0]; 282 count[0] = 0; 283 } else { 284 ak = a; 285 top[255] = a + n; 286 count[255] = 0; 287 } 288 for (cp = count + bmin; nc > 0; cp++) { 289 while (*cp == 0) 290 cp++; 291 if ((c = *cp) > 1) { 292 if (c > bigc) { 293 bigc = c; 294 sp1 = sp; 295 } 296 push(ak, c, i+1); 297 } 298 top[cp-count] = ak += c; 299 *cp = 0; /* Reset count[]. */ 300 nc--; 301 } 302 swap(*sp0, *sp1, temp); 303 304 for (ak = ta + n, ai = a+n; ak > ta;) /* Copy to temp. */ 305 *--ak = *--ai; 306 for (ak = ta+n; --ak >= ta;) /* Deal to piles. */ 307 *--top[tr[(*ak)[i]]] = *ak; 308 } 309 } 310 311 /* insertion sort */ 312 static inline void 313 simplesort(const u_char **a, int n, int b, const u_char *tr, u_int endch) 314 { 315 u_char ch; 316 const u_char **ak, **ai, *s, *t; 317 318 _DIAGASSERT(a != NULL); 319 _DIAGASSERT(tr != NULL); 320 321 for (ak = a+1; --n >= 1; ak++) 322 for (ai = ak; ai > a; ai--) { 323 for (s = ai[0] + b, t = ai[-1] + b; 324 (ch = tr[*s]) != endch; s++, t++) 325 if (ch != tr[*t]) 326 break; 327 if (ch >= tr[*t]) 328 break; 329 swap(ai[0], ai[-1], s); 330 } 331 } 332