1/* $OpenBSD: radixsort.c,v 1.9 2007/09/02 15:19:17 deraadt Exp $ */ 2/*- 3 * Copyright (c) 1990, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * Peter McIlroy and by Dan Bernstein at New York University, 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34/* 35 * Radixsort routines. 36 * 37 * Program r_sort_a() is unstable but uses O(logN) extra memory for a stack. 38 * Use radixsort(a, n, trace, endchar) for this case. 39 * 40 * For stable sorting (using N extra pointers) use sradixsort(), which calls 41 * r_sort_b(). 42 * 43 * For a description of this code, see D. McIlroy, P. McIlroy, K. Bostic, 44 * "Engineering Radix Sort". 45 */ 46 47#include <sys/types.h> 48#include <stdlib.h> 49#include <errno.h> 50 51typedef struct { 52 const u_char **sa; 53 int sn, si; 54} stack; 55 56static __inline void simplesort 57(const u_char **, int, int, const u_char *, u_int); 58static void r_sort_a(const u_char **, int, int, const u_char *, u_int); 59static void r_sort_b(const u_char **, 60 const u_char **, int, int, const u_char *, u_int); 61 62#define THRESHOLD 20 /* Divert to simplesort(). */ 63#define SIZE 512 /* Default stack size. */ 64 65#define SETUP { \ 66 if (tab == NULL) { \ 67 tr = tr0; \ 68 for (c = 0; c < endch; c++) \ 69 tr0[c] = c + 1; \ 70 tr0[c] = 0; \ 71 for (c++; c < 256; c++) \ 72 tr0[c] = c; \ 73 endch = 0; \ 74 } else { \ 75 endch = tab[endch]; \ 76 tr = tab; \ 77 if (endch != 0 && endch != 255) { \ 78 errno = EINVAL; \ 79 return (-1); \ 80 } \ 81 } \ 82} 83 84int 85radixsort(const u_char **a, int n, const u_char *tab, u_int endch) 86{ 87 const u_char *tr; 88 int c; 89 u_char tr0[256]; 90 91 SETUP; 92 r_sort_a(a, n, 0, tr, endch); 93 return (0); 94} 95 96int 97sradixsort(const u_char **a, int n, const u_char *tab, u_int endch) 98{ 99 const u_char *tr, **ta; 100 int c; 101 u_char tr0[256]; 102 103 SETUP; 104 if (n < THRESHOLD) 105 simplesort(a, n, 0, tr, endch); 106 else { 107 if ((ta = calloc(n, sizeof(a))) == NULL) 108 return (-1); 109 r_sort_b(a, ta, n, 0, tr, endch); 110 free(ta); 111 } 112 return (0); 113} 114 115#define empty(s) (s >= sp) 116#define pop(a, n, i) a = (--sp)->sa, n = sp->sn, i = sp->si 117#define push(a, n, i) sp->sa = a, sp->sn = n, (sp++)->si = i 118#define swap(a, b, t) t = a, a = b, b = t 119 120/* Unstable, in-place sort. */ 121void 122r_sort_a(const u_char **a, int n, int i, const u_char *tr, u_int endch) 123{ 124 static int count[256], nc, bmin; 125 int c; 126 const u_char **ak, *r; 127 stack s[SIZE], *sp, *sp0, *sp1, temp; 128 int *cp, bigc; 129 const u_char **an, *t, **aj, **top[256]; 130 131 /* Set up stack. */ 132 sp = s; 133 push(a, n, i); 134 while (!empty(s)) { 135 pop(a, n, i); 136 if (n < THRESHOLD) { 137 simplesort(a, n, i, tr, endch); 138 continue; 139 } 140 an = a + n; 141 142 /* Make character histogram. */ 143 if (nc == 0) { 144 bmin = 255; /* First occupied bin, excluding eos. */ 145 for (ak = a; ak < an;) { 146 c = tr[(*ak++)[i]]; 147 if (++count[c] == 1 && c != endch) { 148 if (c < bmin) 149 bmin = c; 150 nc++; 151 } 152 } 153 if (sp + nc > s + SIZE) { /* Get more stack. */ 154 r_sort_a(a, n, i, tr, endch); 155 continue; 156 } 157 } 158 159 /* 160 * Set top[]; push incompletely sorted bins onto stack. 161 * top[] = pointers to last out-of-place element in bins. 162 * count[] = counts of elements in bins. 163 * Before permuting: top[c-1] + count[c] = top[c]; 164 * during deal: top[c] counts down to top[c-1]. 165 */ 166 sp0 = sp1 = sp; /* Stack position of biggest bin. */ 167 bigc = 2; /* Size of biggest bin. */ 168 if (endch == 0) /* Special case: set top[eos]. */ 169 top[0] = ak = a + count[0]; 170 else { 171 ak = a; 172 top[255] = an; 173 } 174 for (cp = count + bmin; nc > 0; cp++) { 175 while (*cp == 0) /* Find next non-empty pile. */ 176 cp++; 177 if (*cp > 1) { 178 if (*cp > bigc) { 179 bigc = *cp; 180 sp1 = sp; 181 } 182 push(ak, *cp, i+1); 183 } 184 top[cp-count] = ak += *cp; 185 nc--; 186 } 187 swap(*sp0, *sp1, temp); /* Play it safe -- biggest bin last. */ 188 189 /* 190 * Permute misplacements home. Already home: everything 191 * before aj, and in bin[c], items from top[c] on. 192 * Inner loop: 193 * r = next element to put in place; 194 * ak = top[r[i]] = location to put the next element. 195 * aj = bottom of 1st disordered bin. 196 * Outer loop: 197 * Once the 1st disordered bin is done, ie. aj >= ak, 198 * aj<-aj + count[c] connects the bins in a linked list; 199 * reset count[c]. 200 */ 201 for (aj = a; aj < an; *aj = r, aj += count[c], count[c] = 0) 202 for (r = *aj; aj < (ak = --top[c = tr[r[i]]]);) 203 swap(*ak, r, t); 204 } 205} 206 207/* Stable sort, requiring additional memory. */ 208void 209r_sort_b(const u_char **a, const u_char **ta, int n, int i, const u_char *tr, 210 u_int endch) 211{ 212 static int count[256], nc, bmin; 213 int c; 214 const u_char **ak, **ai; 215 stack s[512], *sp, *sp0, *sp1, temp; 216 const u_char **top[256]; 217 int *cp, bigc; 218 219 sp = s; 220 push(a, n, i); 221 while (!empty(s)) { 222 pop(a, n, i); 223 if (n < THRESHOLD) { 224 simplesort(a, n, i, tr, endch); 225 continue; 226 } 227 228 if (nc == 0) { 229 bmin = 255; 230 for (ak = a + n; --ak >= a;) { 231 c = tr[(*ak)[i]]; 232 if (++count[c] == 1 && c != endch) { 233 if (c < bmin) 234 bmin = c; 235 nc++; 236 } 237 } 238 if (sp + nc > s + SIZE) { 239 r_sort_b(a, ta, n, i, tr, endch); 240 continue; 241 } 242 } 243 244 sp0 = sp1 = sp; 245 bigc = 2; 246 if (endch == 0) { 247 top[0] = ak = a + count[0]; 248 count[0] = 0; 249 } else { 250 ak = a; 251 top[255] = a + n; 252 count[255] = 0; 253 } 254 for (cp = count + bmin; nc > 0; cp++) { 255 while (*cp == 0) 256 cp++; 257 if ((c = *cp) > 1) { 258 if (c > bigc) { 259 bigc = c; 260 sp1 = sp; 261 } 262 push(ak, c, i+1); 263 } 264 top[cp-count] = ak += c; 265 *cp = 0; /* Reset count[]. */ 266 nc--; 267 } 268 swap(*sp0, *sp1, temp); 269 270 for (ak = ta + n, ai = a+n; ak > ta;) /* Copy to temp. */ 271 *--ak = *--ai; 272 for (ak = ta+n; --ak >= ta;) /* Deal to piles. */ 273 *--top[tr[(*ak)[i]]] = *ak; 274 } 275} 276 277static __inline void 278simplesort(const u_char **a, int n, int b, const u_char *tr, u_int endch) 279 /* insertion sort */ 280{ 281 u_char ch; 282 const u_char **ak, **ai, *s, *t; 283 284 for (ak = a+1; --n >= 1; ak++) 285 for (ai = ak; ai > a; ai--) { 286 for (s = ai[0] + b, t = ai[-1] + b; 287 (ch = tr[*s]) != endch; s++, t++) 288 if (ch != tr[*t]) 289 break; 290 if (ch >= tr[*t]) 291 break; 292 swap(ai[0], ai[-1], s); 293 } 294} 295