1 /*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * 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 * %sccs.include.redist.c% 9 */ 10 11 #if defined(LIBC_SCCS) && !defined(lint) 12 static char sccsid[] = "@(#)radixsort.c 5.14 (Berkeley) 07/01/92"; 13 #endif /* LIBC_SCCS and not lint */ 14 15 /* 16 * Radixsort routines. 17 * 18 * Program r_sort_a() is unstable but uses O(logN) extra memory for a stack. 19 * Use radixsort(a, n, trace, endchar) for this case. 20 * 21 * For stable sorting (using N extra pointers) use sradixsort(), which calls 22 * r_sort_b(). 23 * 24 * For a description of this code, see D. McIlroy, P. McIlroy, K. Bostic, 25 * "Engineering Radix Sort". 26 */ 27 28 #include <sys/types.h> 29 #include <stdlib.h> 30 #include <stddef.h> 31 #include <errno.h> 32 33 typedef struct { 34 const u_char **sa; 35 int sn, si; 36 } stack; 37 38 static void simplesort __P((const u_char **, int, int, const u_char *, u_int)); 39 static void r_sort_a __P((const u_char **, int, int, const u_char *, u_int)); 40 static void r_sort_b __P((const u_char **, 41 const u_char **, int, int, const u_char *, u_int)); 42 43 #define THRESHOLD 20 /* Divert to simplesort(). */ 44 #define SIZE 512 /* Default stack size. */ 45 46 #define SETUP { \ 47 if (tab == NULL) { \ 48 tr = tr0; \ 49 for (c = 0; c < endch; c++) \ 50 tr0[c] = c + 1; \ 51 tr0[c] = 0; \ 52 for (c++; c < 256; c++) \ 53 tr0[c] = c; \ 54 endch = 0; \ 55 } else { \ 56 endch = tab[endch]; \ 57 tr = tab; \ 58 if (endch != 0 && endch != 255) { \ 59 errno = EINVAL; \ 60 return (-1); \ 61 } \ 62 } \ 63 } 64 65 int 66 radixsort(a, n, tab, endch) 67 const u_char **a, *tab; 68 int n; 69 u_int endch; 70 { 71 const u_char *tr; 72 int c; 73 u_char tr0[256]; 74 75 SETUP; 76 r_sort_a(a, n, 0, tr, endch); 77 return (0); 78 } 79 80 int 81 sradixsort(a, n, tab, endch) 82 const u_char **a, *tab; 83 int n; 84 u_int endch; 85 { 86 const u_char *tr, **ta; 87 int c; 88 u_char tr0[256]; 89 90 SETUP; 91 if (n < THRESHOLD) 92 simplesort(a, n, 0, tr, endch); 93 else { 94 if ((ta = malloc(n * sizeof(a))) == NULL) 95 return (-1); 96 r_sort_b(a, ta, n, 0, tr, endch); 97 free(ta); 98 } 99 return (0); 100 } 101 102 #define empty(s) (s >= sp) 103 #define pop(a, n, i) a = (--sp)->sa, n = sp->sn, i = sp->si 104 #define push(a, n, i) sp->sa = a, sp->sn = n, (sp++)->si = i 105 #define swap(a, b, t) t = a, a = b, b = t 106 107 /* Unstable, in-place sort. */ 108 void 109 r_sort_a(a, n, i, tr, endch) 110 const u_char **a; 111 int n, i; 112 const u_char *tr; 113 u_int endch; 114 { 115 static int count[256], nc, bmin; 116 register int c; 117 register const u_char **ak, *r; 118 stack s[SIZE], *sp, *sp0, *sp1, temp; 119 int *cp, bigc; 120 const u_char **an, *t, **aj, **top[256]; 121 122 /* Set up stack. */ 123 sp = s; 124 push(a, n, i); 125 while (!empty(s)) { 126 pop(a, n, i); 127 if (n < THRESHOLD) { 128 simplesort(a, n, i, tr, endch); 129 continue; 130 } 131 an = a + n; 132 133 /* Make character histogram. */ 134 if (nc == 0) { 135 bmin = 255; /* First occupied bin, excluding eos. */ 136 for (ak = a; ak < an;) { 137 c = tr[(*ak++)[i]]; 138 if (++count[c] == 1 && c != endch) { 139 if (c < bmin) 140 bmin = c; 141 nc++; 142 } 143 } 144 if (sp + nc > s + SIZE) { /* Get more stack. */ 145 r_sort_a(a, n, i, tr, endch); 146 continue; 147 } 148 } 149 150 /* 151 * Set top[]; push incompletely sorted bins onto stack. 152 * top[] = pointers to last out-of-place element in bins. 153 * count[] = counts of elements in bins. 154 * Before permuting: top[c-1] + count[c] = top[c]; 155 * during deal: top[c] counts down to top[c-1]. 156 */ 157 sp0 = sp1 = sp; /* Stack position of biggest bin. */ 158 bigc = 2; /* Size of biggest bin. */ 159 if (endch == 0) /* Special case: set top[eos]. */ 160 top[0] = ak = a + count[0]; 161 else { 162 ak = a; 163 top[255] = an; 164 } 165 for (cp = count + bmin; nc > 0; cp++) { 166 while (*cp == 0) /* Find next non-empty pile. */ 167 cp++; 168 if (*cp > 1) { 169 if (*cp > bigc) { 170 bigc = *cp; 171 sp1 = sp; 172 } 173 push(ak, *cp, i+1); 174 } 175 top[cp-count] = ak += *cp; 176 nc--; 177 } 178 swap(*sp0, *sp1, temp); /* Play it safe -- biggest bin last. */ 179 180 /* 181 * Permute misplacements home. Already home: everything 182 * before aj, and in bin[c], items from top[c] on. 183 * Inner loop: 184 * r = next element to put in place; 185 * ak = top[r[i]] = location to put the next element. 186 * aj = bottom of 1st disordered bin. 187 * Outer loop: 188 * Once the 1st disordered bin is done, ie. aj >= ak, 189 * aj<-aj + count[c] connects the bins in a linked list; 190 * reset count[c]. 191 */ 192 for (aj = a; aj < an; *aj = r, aj += count[c], count[c] = 0) 193 for (r = *aj; aj < (ak = --top[c = tr[r[i]]]);) 194 swap(*ak, r, t); 195 } 196 } 197 198 /* Stable sort, requiring additional memory. */ 199 void 200 r_sort_b(a, ta, n, i, tr, endch) 201 const u_char **a, **ta; 202 int n, i; 203 const u_char *tr; 204 u_int endch; 205 { 206 static int count[256], nc, bmin; 207 register int c; 208 register const u_char **ak, **ai; 209 stack s[512], *sp, *sp0, *sp1, temp; 210 const u_char **top[256]; 211 int *cp, bigc; 212 213 sp = s; 214 push(a, n, i); 215 while (!empty(s)) { 216 pop(a, n, i); 217 if (n < THRESHOLD) { 218 simplesort(a, n, i, tr, endch); 219 continue; 220 } 221 222 if (nc == 0) { 223 bmin = 255; 224 for (ak = a + n; --ak >= a;) { 225 c = tr[(*ak)[i]]; 226 if (++count[c] == 1 && c != endch) { 227 if (c < bmin) 228 bmin = c; 229 nc++; 230 } 231 } 232 if (sp + nc > s + SIZE) { 233 r_sort_b(a, ta, n, i, tr, endch); 234 continue; 235 } 236 } 237 238 sp0 = sp1 = sp; 239 bigc = 2; 240 if (endch == 0) { 241 top[0] = ak = a + count[0]; 242 count[0] = 0; 243 } else { 244 ak = a; 245 top[255] = a + n; 246 count[255] = 0; 247 } 248 for (cp = count + bmin; nc > 0; cp++) { 249 while (*cp == 0) 250 cp++; 251 if ((c = *cp) > 1) { 252 if (c > bigc) { 253 bigc = c; 254 sp1 = sp; 255 } 256 push(ak, c, i+1); 257 } 258 top[cp-count] = ak += c; 259 *cp = 0; /* Reset count[]. */ 260 nc--; 261 } 262 swap(*sp0, *sp1, temp); 263 264 for (ak = ta + n, ai = a+n; ak > ta;) /* Copy to temp. */ 265 *--ak = *--ai; 266 for (ak = ta+n; --ak >= ta;) /* Deal to piles. */ 267 *--top[tr[(*ak)[i]]] = *ak; 268 } 269 } 270 271 static void 272 simplesort(a, n, b, tr, endch) /* insertion sort */ 273 register const u_char **a; 274 int n, b; 275 register const u_char *tr; 276 u_int endch; 277 { 278 register u_char ch; 279 const u_char **ak, **ai, *s, *t; 280 281 for (ak = a+1; --n >= 1; ak++) 282 for (ai = ak; ai > a; ai--) { 283 for (s = ai[0] + b, t = ai[-1] + b; 284 (ch = tr[*s]) != endch; s++, t++) 285 if (ch != tr[*t]) 286 break; 287 if (ch >= tr[*t]) 288 break; 289 swap(ai[0], ai[-1], s); 290 } 291 } 292