1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1992, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #if defined(LIBC_SCCS) && !defined(lint) 33 static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93"; 34 #endif /* LIBC_SCCS and not lint */ 35 #include <sys/cdefs.h> 36 __FBSDID("$FreeBSD$"); 37 38 #include <errno.h> 39 #include <stdint.h> 40 #include <stdlib.h> 41 #include <string.h> 42 #include "libc_private.h" 43 44 #if defined(I_AM_QSORT_R) 45 typedef int cmp_t(const void *, const void *, void *); 46 #elif defined(I_AM_QSORT_R_COMPAT) 47 typedef int cmp_t(void *, const void *, const void *); 48 #elif defined(I_AM_QSORT_S) 49 typedef int cmp_t(const void *, const void *, void *); 50 #else 51 typedef int cmp_t(const void *, const void *); 52 #endif 53 static inline char *med3(char *, char *, char *, cmp_t *, void *); 54 55 #define MIN(a, b) ((a) < (b) ? a : b) 56 57 /* 58 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 59 */ 60 61 static inline void 62 swapfunc(char *a, char *b, size_t es) 63 { 64 char t; 65 66 do { 67 t = *a; 68 *a++ = *b; 69 *b++ = t; 70 } while (--es > 0); 71 } 72 73 #define vecswap(a, b, n) \ 74 if ((n) > 0) swapfunc(a, b, n) 75 76 #if defined(I_AM_QSORT_R) 77 #define CMP(t, x, y) (cmp((x), (y), (t))) 78 #elif defined(I_AM_QSORT_R_COMPAT) 79 #define CMP(t, x, y) (cmp((t), (x), (y))) 80 #elif defined(I_AM_QSORT_S) 81 #define CMP(t, x, y) (cmp((x), (y), (t))) 82 #else 83 #define CMP(t, x, y) (cmp((x), (y))) 84 #endif 85 86 static inline char * 87 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk 88 #if !defined(I_AM_QSORT_R) && !defined(I_AM_QSORT_R_COMPAT) && !defined(I_AM_QSORT_S) 89 __unused 90 #endif 91 ) 92 { 93 return CMP(thunk, a, b) < 0 ? 94 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a )) 95 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c )); 96 } 97 98 /* 99 * The actual qsort() implementation is static to avoid preemptible calls when 100 * recursing. Also give them different names for improved debugging. 101 */ 102 #if defined(I_AM_QSORT_R) 103 #define local_qsort local_qsort_r 104 #elif defined(I_AM_QSORT_R_COMPAT) 105 #define local_qsort local_qsort_r_compat 106 #elif defined(I_AM_QSORT_S) 107 #define local_qsort local_qsort_s 108 #endif 109 static void 110 local_qsort(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk) 111 { 112 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 113 size_t d1, d2; 114 int cmp_result; 115 int swap_cnt; 116 117 /* if there are less than 2 elements, then sorting is not needed */ 118 if (__predict_false(n < 2)) 119 return; 120 loop: 121 swap_cnt = 0; 122 if (n < 7) { 123 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 124 for (pl = pm; 125 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 126 pl -= es) 127 swapfunc(pl, pl - es, es); 128 return; 129 } 130 pm = (char *)a + (n / 2) * es; 131 if (n > 7) { 132 pl = a; 133 pn = (char *)a + (n - 1) * es; 134 if (n > 40) { 135 size_t d = (n / 8) * es; 136 137 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); 138 pm = med3(pm - d, pm, pm + d, cmp, thunk); 139 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); 140 } 141 pm = med3(pl, pm, pn, cmp, thunk); 142 } 143 swapfunc(a, pm, es); 144 pa = pb = (char *)a + es; 145 146 pc = pd = (char *)a + (n - 1) * es; 147 for (;;) { 148 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) { 149 if (cmp_result == 0) { 150 swap_cnt = 1; 151 swapfunc(pa, pb, es); 152 pa += es; 153 } 154 pb += es; 155 } 156 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) { 157 if (cmp_result == 0) { 158 swap_cnt = 1; 159 swapfunc(pc, pd, es); 160 pd -= es; 161 } 162 pc -= es; 163 } 164 if (pb > pc) 165 break; 166 swapfunc(pb, pc, es); 167 swap_cnt = 1; 168 pb += es; 169 pc -= es; 170 } 171 if (swap_cnt == 0) { /* Switch to insertion sort */ 172 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 173 for (pl = pm; 174 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 175 pl -= es) 176 swapfunc(pl, pl - es, es); 177 return; 178 } 179 180 pn = (char *)a + n * es; 181 d1 = MIN(pa - (char *)a, pb - pa); 182 vecswap(a, pb - d1, d1); 183 /* 184 * Cast es to preserve signedness of right-hand side of MIN() 185 * expression, to avoid sign ambiguity in the implied comparison. es 186 * is safely within [0, SSIZE_MAX]. 187 */ 188 d1 = MIN(pd - pc, pn - pd - (ssize_t)es); 189 vecswap(pb, pn - d1, d1); 190 191 d1 = pb - pa; 192 d2 = pd - pc; 193 if (d1 <= d2) { 194 /* Recurse on left partition, then iterate on right partition */ 195 if (d1 > es) { 196 local_qsort(a, d1 / es, es, cmp, thunk); 197 } 198 if (d2 > es) { 199 /* Iterate rather than recurse to save stack space */ 200 /* qsort(pn - d2, d2 / es, es, cmp); */ 201 a = pn - d2; 202 n = d2 / es; 203 goto loop; 204 } 205 } else { 206 /* Recurse on right partition, then iterate on left partition */ 207 if (d2 > es) { 208 local_qsort(pn - d2, d2 / es, es, cmp, thunk); 209 } 210 if (d1 > es) { 211 /* Iterate rather than recurse to save stack space */ 212 /* qsort(a, d1 / es, es, cmp); */ 213 n = d1 / es; 214 goto loop; 215 } 216 } 217 } 218 219 #if defined(I_AM_QSORT_R) 220 void 221 (qsort_r)(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk) 222 { 223 local_qsort_r(a, n, es, cmp, thunk); 224 } 225 #elif defined(I_AM_QSORT_R_COMPAT) 226 void 227 __qsort_r_compat(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) 228 { 229 local_qsort_r_compat(a, n, es, cmp, thunk); 230 } 231 #elif defined(I_AM_QSORT_S) 232 errno_t 233 qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk) 234 { 235 if (n > RSIZE_MAX) { 236 __throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL); 237 return (EINVAL); 238 } else if (es > RSIZE_MAX) { 239 __throw_constraint_handler_s("qsort_s : es > RSIZE_MAX", 240 EINVAL); 241 return (EINVAL); 242 } else if (n != 0) { 243 if (a == NULL) { 244 __throw_constraint_handler_s("qsort_s : a == NULL", 245 EINVAL); 246 return (EINVAL); 247 } else if (cmp == NULL) { 248 __throw_constraint_handler_s("qsort_s : cmp == NULL", 249 EINVAL); 250 return (EINVAL); 251 } else if (es <= 0) { 252 __throw_constraint_handler_s("qsort_s : es <= 0", 253 EINVAL); 254 return (EINVAL); 255 } 256 } 257 258 local_qsort_s(a, n, es, cmp, thunk); 259 return (0); 260 } 261 #else 262 void 263 qsort(void *a, size_t n, size_t es, cmp_t *cmp) 264 { 265 local_qsort(a, n, es, cmp, NULL); 266 } 267 #endif 268