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 #include <errno.h> 37 #include <stdint.h> 38 #include <stdlib.h> 39 #include <string.h> 40 #include "libc_private.h" 41 42 #if defined(I_AM_QSORT_R) 43 typedef int cmp_t(const void *, const void *, void *); 44 #elif defined(I_AM_QSORT_R_COMPAT) 45 typedef int cmp_t(void *, const void *, const void *); 46 #elif defined(I_AM_QSORT_S) 47 typedef int cmp_t(const void *, const void *, void *); 48 #else 49 typedef int cmp_t(const void *, const void *); 50 #endif 51 static inline char *med3(char *, char *, char *, cmp_t *, void *); 52 53 #define MIN(a, b) ((a) < (b) ? a : b) 54 55 /* 56 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 57 */ 58 59 static inline void 60 swapfunc(char *a, char *b, size_t es) 61 { 62 char t; 63 64 do { 65 t = *a; 66 *a++ = *b; 67 *b++ = t; 68 } while (--es > 0); 69 } 70 71 #define vecswap(a, b, n) \ 72 if ((n) > 0) swapfunc(a, b, n) 73 74 #if defined(I_AM_QSORT_R) 75 #define CMP(t, x, y) (cmp((x), (y), (t))) 76 #elif defined(I_AM_QSORT_R_COMPAT) 77 #define CMP(t, x, y) (cmp((t), (x), (y))) 78 #elif defined(I_AM_QSORT_S) 79 #define CMP(t, x, y) (cmp((x), (y), (t))) 80 #else 81 #define CMP(t, x, y) (cmp((x), (y))) 82 #endif 83 84 static inline char * 85 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk 86 #if !defined(I_AM_QSORT_R) && !defined(I_AM_QSORT_R_COMPAT) && !defined(I_AM_QSORT_S) 87 __unused 88 #endif 89 ) 90 { 91 return CMP(thunk, a, b) < 0 ? 92 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a )) 93 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c )); 94 } 95 96 /* 97 * The actual qsort() implementation is static to avoid preemptible calls when 98 * recursing. Also give them different names for improved debugging. 99 */ 100 #if defined(I_AM_QSORT_R) 101 #define local_qsort local_qsort_r 102 #elif defined(I_AM_QSORT_R_COMPAT) 103 #define local_qsort local_qsort_r_compat 104 #elif defined(I_AM_QSORT_S) 105 #define local_qsort local_qsort_s 106 #endif 107 static void 108 local_qsort(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk) 109 { 110 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 111 size_t d1, d2; 112 int cmp_result; 113 int swap_cnt; 114 115 /* if there are less than 2 elements, then sorting is not needed */ 116 if (__predict_false(n < 2)) 117 return; 118 loop: 119 swap_cnt = 0; 120 if (n < 7) { 121 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 122 for (pl = pm; 123 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 124 pl -= es) 125 swapfunc(pl, pl - es, es); 126 return; 127 } 128 pm = (char *)a + (n / 2) * es; 129 if (n > 7) { 130 pl = a; 131 pn = (char *)a + (n - 1) * es; 132 if (n > 40) { 133 size_t d = (n / 8) * es; 134 135 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); 136 pm = med3(pm - d, pm, pm + d, cmp, thunk); 137 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); 138 } 139 pm = med3(pl, pm, pn, cmp, thunk); 140 } 141 swapfunc(a, pm, es); 142 pa = pb = (char *)a + es; 143 144 pc = pd = (char *)a + (n - 1) * es; 145 for (;;) { 146 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) { 147 if (cmp_result == 0) { 148 swap_cnt = 1; 149 swapfunc(pa, pb, es); 150 pa += es; 151 } 152 pb += es; 153 } 154 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) { 155 if (cmp_result == 0) { 156 swap_cnt = 1; 157 swapfunc(pc, pd, es); 158 pd -= es; 159 } 160 pc -= es; 161 } 162 if (pb > pc) 163 break; 164 swapfunc(pb, pc, es); 165 swap_cnt = 1; 166 pb += es; 167 pc -= es; 168 } 169 if (swap_cnt == 0) { /* Switch to insertion sort */ 170 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 171 for (pl = pm; 172 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 173 pl -= es) 174 swapfunc(pl, pl - es, es); 175 return; 176 } 177 178 pn = (char *)a + n * es; 179 d1 = MIN(pa - (char *)a, pb - pa); 180 vecswap(a, pb - d1, d1); 181 /* 182 * Cast es to preserve signedness of right-hand side of MIN() 183 * expression, to avoid sign ambiguity in the implied comparison. es 184 * is safely within [0, SSIZE_MAX]. 185 */ 186 d1 = MIN(pd - pc, pn - pd - (ssize_t)es); 187 vecswap(pb, pn - d1, d1); 188 189 d1 = pb - pa; 190 d2 = pd - pc; 191 if (d1 <= d2) { 192 /* Recurse on left partition, then iterate on right partition */ 193 if (d1 > es) { 194 local_qsort(a, d1 / es, es, cmp, thunk); 195 } 196 if (d2 > es) { 197 /* Iterate rather than recurse to save stack space */ 198 /* qsort(pn - d2, d2 / es, es, cmp); */ 199 a = pn - d2; 200 n = d2 / es; 201 goto loop; 202 } 203 } else { 204 /* Recurse on right partition, then iterate on left partition */ 205 if (d2 > es) { 206 local_qsort(pn - d2, d2 / es, es, cmp, thunk); 207 } 208 if (d1 > es) { 209 /* Iterate rather than recurse to save stack space */ 210 /* qsort(a, d1 / es, es, cmp); */ 211 n = d1 / es; 212 goto loop; 213 } 214 } 215 } 216 217 #if defined(I_AM_QSORT_R) 218 void 219 (qsort_r)(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk) 220 { 221 local_qsort_r(a, n, es, cmp, thunk); 222 } 223 #elif defined(I_AM_QSORT_R_COMPAT) 224 void 225 __qsort_r_compat(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) 226 { 227 local_qsort_r_compat(a, n, es, cmp, thunk); 228 } 229 #elif defined(I_AM_QSORT_S) 230 errno_t 231 qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk) 232 { 233 if (n > RSIZE_MAX) { 234 __throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL); 235 return (EINVAL); 236 } else if (es > RSIZE_MAX) { 237 __throw_constraint_handler_s("qsort_s : es > RSIZE_MAX", 238 EINVAL); 239 return (EINVAL); 240 } else if (n != 0) { 241 if (a == NULL) { 242 __throw_constraint_handler_s("qsort_s : a == NULL", 243 EINVAL); 244 return (EINVAL); 245 } else if (cmp == NULL) { 246 __throw_constraint_handler_s("qsort_s : cmp == NULL", 247 EINVAL); 248 return (EINVAL); 249 } else if (es <= 0) { 250 __throw_constraint_handler_s("qsort_s : es <= 0", 251 EINVAL); 252 return (EINVAL); 253 } 254 } 255 256 local_qsort_s(a, n, es, cmp, thunk); 257 return (0); 258 } 259 #else 260 void 261 qsort(void *a, size_t n, size_t es, cmp_t *cmp) 262 { 263 local_qsort(a, n, es, cmp, NULL); 264 } 265 #endif 266