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 <errno.h> 36 #include <stdint.h> 37 #include <stdlib.h> 38 #include <string.h> 39 #include "libc_private.h" 40 41 #if defined(I_AM_QSORT_R) 42 typedef int cmp_t(const void *, const void *, void *); 43 #elif defined(I_AM_QSORT_R_COMPAT) 44 typedef int cmp_t(void *, const void *, const void *); 45 #elif defined(I_AM_QSORT_S) 46 typedef int cmp_t(const void *, const void *, void *); 47 #else 48 typedef int cmp_t(const void *, const void *); 49 #endif 50 static inline char *med3(char *, char *, char *, cmp_t *, void *); 51 52 #define MIN(a, b) ((a) < (b) ? a : b) 53 54 /* 55 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 56 */ 57 58 static inline void 59 swapfunc(char *a, char *b, size_t es) 60 { 61 char t; 62 63 do { 64 t = *a; 65 *a++ = *b; 66 *b++ = t; 67 } while (--es > 0); 68 } 69 70 #define vecswap(a, b, n) \ 71 if ((n) > 0) swapfunc(a, b, n) 72 73 #if defined(I_AM_QSORT_R) 74 #define CMP(t, x, y) (cmp((x), (y), (t))) 75 #elif defined(I_AM_QSORT_R_COMPAT) 76 #define CMP(t, x, y) (cmp((t), (x), (y))) 77 #elif defined(I_AM_QSORT_S) 78 #define CMP(t, x, y) (cmp((x), (y), (t))) 79 #else 80 #define CMP(t, x, y) (cmp((x), (y))) 81 #endif 82 83 static inline char * 84 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk 85 #if !defined(I_AM_QSORT_R) && !defined(I_AM_QSORT_R_COMPAT) && !defined(I_AM_QSORT_S) 86 __unused 87 #endif 88 ) 89 { 90 return CMP(thunk, a, b) < 0 ? 91 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a )) 92 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c )); 93 } 94 95 /* 96 * The actual qsort() implementation is static to avoid preemptible calls when 97 * recursing. Also give them different names for improved debugging. 98 */ 99 #if defined(I_AM_QSORT_R) 100 #define local_qsort local_qsort_r 101 #elif defined(I_AM_QSORT_R_COMPAT) 102 #define local_qsort local_qsort_r_compat 103 #elif defined(I_AM_QSORT_S) 104 #define local_qsort local_qsort_s 105 #endif 106 static void 107 local_qsort(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk) 108 { 109 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 110 size_t d1, d2; 111 int cmp_result; 112 int swap_cnt; 113 114 /* if there are less than 2 elements, then sorting is not needed */ 115 if (__predict_false(n < 2)) 116 return; 117 loop: 118 swap_cnt = 0; 119 if (n < 7) { 120 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 121 for (pl = pm; 122 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 123 pl -= es) 124 swapfunc(pl, pl - es, es); 125 return; 126 } 127 pm = (char *)a + (n / 2) * es; 128 if (n > 7) { 129 pl = a; 130 pn = (char *)a + (n - 1) * es; 131 if (n > 40) { 132 size_t d = (n / 8) * es; 133 134 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); 135 pm = med3(pm - d, pm, pm + d, cmp, thunk); 136 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); 137 } 138 pm = med3(pl, pm, pn, cmp, thunk); 139 } 140 swapfunc(a, pm, es); 141 pa = pb = (char *)a + es; 142 143 pc = pd = (char *)a + (n - 1) * es; 144 for (;;) { 145 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) { 146 if (cmp_result == 0) { 147 swap_cnt = 1; 148 swapfunc(pa, pb, es); 149 pa += es; 150 } 151 pb += es; 152 } 153 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) { 154 if (cmp_result == 0) { 155 swap_cnt = 1; 156 swapfunc(pc, pd, es); 157 pd -= es; 158 } 159 pc -= es; 160 } 161 if (pb > pc) 162 break; 163 swapfunc(pb, pc, es); 164 swap_cnt = 1; 165 pb += es; 166 pc -= es; 167 } 168 if (swap_cnt == 0) { /* Switch to insertion sort */ 169 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 170 for (pl = pm; 171 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 172 pl -= es) 173 swapfunc(pl, pl - es, es); 174 return; 175 } 176 177 pn = (char *)a + n * es; 178 d1 = MIN(pa - (char *)a, pb - pa); 179 vecswap(a, pb - d1, d1); 180 /* 181 * Cast es to preserve signedness of right-hand side of MIN() 182 * expression, to avoid sign ambiguity in the implied comparison. es 183 * is safely within [0, SSIZE_MAX]. 184 */ 185 d1 = MIN(pd - pc, pn - pd - (ssize_t)es); 186 vecswap(pb, pn - d1, d1); 187 188 d1 = pb - pa; 189 d2 = pd - pc; 190 if (d1 <= d2) { 191 /* Recurse on left partition, then iterate on right partition */ 192 if (d1 > es) { 193 local_qsort(a, d1 / es, es, cmp, thunk); 194 } 195 if (d2 > es) { 196 /* Iterate rather than recurse to save stack space */ 197 /* qsort(pn - d2, d2 / es, es, cmp); */ 198 a = pn - d2; 199 n = d2 / es; 200 goto loop; 201 } 202 } else { 203 /* Recurse on right partition, then iterate on left partition */ 204 if (d2 > es) { 205 local_qsort(pn - d2, d2 / es, es, cmp, thunk); 206 } 207 if (d1 > es) { 208 /* Iterate rather than recurse to save stack space */ 209 /* qsort(a, d1 / es, es, cmp); */ 210 n = d1 / es; 211 goto loop; 212 } 213 } 214 } 215 216 #if defined(I_AM_QSORT_R) 217 void 218 (qsort_r)(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk) 219 { 220 local_qsort_r(a, n, es, cmp, thunk); 221 } 222 #elif defined(I_AM_QSORT_R_COMPAT) 223 void 224 __qsort_r_compat(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) 225 { 226 local_qsort_r_compat(a, n, es, cmp, thunk); 227 } 228 #elif defined(I_AM_QSORT_S) 229 errno_t 230 qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk) 231 { 232 if (n > RSIZE_MAX) { 233 __throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL); 234 return (EINVAL); 235 } else if (es > RSIZE_MAX) { 236 __throw_constraint_handler_s("qsort_s : es > RSIZE_MAX", 237 EINVAL); 238 return (EINVAL); 239 } else if (n != 0) { 240 if (a == NULL) { 241 __throw_constraint_handler_s("qsort_s : a == NULL", 242 EINVAL); 243 return (EINVAL); 244 } else if (cmp == NULL) { 245 __throw_constraint_handler_s("qsort_s : cmp == NULL", 246 EINVAL); 247 return (EINVAL); 248 } else if (es <= 0) { 249 __throw_constraint_handler_s("qsort_s : es <= 0", 250 EINVAL); 251 return (EINVAL); 252 } 253 } 254 255 local_qsort_s(a, n, es, cmp, thunk); 256 return (0); 257 } 258 #else 259 void 260 qsort(void *a, size_t n, size_t es, cmp_t *cmp) 261 { 262 local_qsort(a, n, es, cmp, NULL); 263 } 264 #endif 265