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 (__predict_false(n == 0)) 118 return; 119 loop: 120 swap_cnt = 0; 121 if (n < 7) { 122 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 123 for (pl = pm; 124 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 125 pl -= es) 126 swapfunc(pl, pl - es, es); 127 return; 128 } 129 pm = (char *)a + (n / 2) * es; 130 if (n > 7) { 131 pl = a; 132 pn = (char *)a + (n - 1) * es; 133 if (n > 40) { 134 size_t d = (n / 8) * es; 135 136 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); 137 pm = med3(pm - d, pm, pm + d, cmp, thunk); 138 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); 139 } 140 pm = med3(pl, pm, pn, cmp, thunk); 141 } 142 swapfunc(a, pm, es); 143 pa = pb = (char *)a + es; 144 145 pc = pd = (char *)a + (n - 1) * es; 146 for (;;) { 147 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) { 148 if (cmp_result == 0) { 149 swap_cnt = 1; 150 swapfunc(pa, pb, es); 151 pa += es; 152 } 153 pb += es; 154 } 155 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) { 156 if (cmp_result == 0) { 157 swap_cnt = 1; 158 swapfunc(pc, pd, es); 159 pd -= es; 160 } 161 pc -= es; 162 } 163 if (pb > pc) 164 break; 165 swapfunc(pb, pc, es); 166 swap_cnt = 1; 167 pb += es; 168 pc -= es; 169 } 170 if (swap_cnt == 0) { /* Switch to insertion sort */ 171 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 172 for (pl = pm; 173 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 174 pl -= es) 175 swapfunc(pl, pl - es, es); 176 return; 177 } 178 179 pn = (char *)a + n * es; 180 d1 = MIN(pa - (char *)a, pb - pa); 181 vecswap(a, pb - d1, d1); 182 /* 183 * Cast es to preserve signedness of right-hand side of MIN() 184 * expression, to avoid sign ambiguity in the implied comparison. es 185 * is safely within [0, SSIZE_MAX]. 186 */ 187 d1 = MIN(pd - pc, pn - pd - (ssize_t)es); 188 vecswap(pb, pn - d1, d1); 189 190 d1 = pb - pa; 191 d2 = pd - pc; 192 if (d1 <= d2) { 193 /* Recurse on left partition, then iterate on right partition */ 194 if (d1 > es) { 195 local_qsort(a, d1 / es, es, cmp, thunk); 196 } 197 if (d2 > es) { 198 /* Iterate rather than recurse to save stack space */ 199 /* qsort(pn - d2, d2 / es, es, cmp); */ 200 a = pn - d2; 201 n = d2 / es; 202 goto loop; 203 } 204 } else { 205 /* Recurse on right partition, then iterate on left partition */ 206 if (d2 > es) { 207 local_qsort(pn - d2, d2 / es, es, cmp, thunk); 208 } 209 if (d1 > es) { 210 /* Iterate rather than recurse to save stack space */ 211 /* qsort(a, d1 / es, es, cmp); */ 212 n = d1 / es; 213 goto loop; 214 } 215 } 216 } 217 218 #if defined(I_AM_QSORT_R) 219 void 220 (qsort_r)(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk) 221 { 222 local_qsort_r(a, n, es, cmp, thunk); 223 } 224 #elif defined(I_AM_QSORT_R_COMPAT) 225 void 226 __qsort_r_compat(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) 227 { 228 local_qsort_r_compat(a, n, es, cmp, thunk); 229 } 230 #elif defined(I_AM_QSORT_S) 231 errno_t 232 qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk) 233 { 234 if (n > RSIZE_MAX) { 235 __throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL); 236 return (EINVAL); 237 } else if (es > RSIZE_MAX) { 238 __throw_constraint_handler_s("qsort_s : es > RSIZE_MAX", 239 EINVAL); 240 return (EINVAL); 241 } else if (n != 0) { 242 if (a == NULL) { 243 __throw_constraint_handler_s("qsort_s : a == NULL", 244 EINVAL); 245 return (EINVAL); 246 } else if (cmp == NULL) { 247 __throw_constraint_handler_s("qsort_s : cmp == NULL", 248 EINVAL); 249 return (EINVAL); 250 } 251 } 252 253 local_qsort_s(a, n, es, cmp, thunk); 254 return (0); 255 } 256 #else 257 void 258 qsort(void *a, size_t n, size_t es, cmp_t *cmp) 259 { 260 local_qsort(a, n, es, cmp, NULL); 261 } 262 #endif 263