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(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((t), (x), (y))) 76 #elif defined(I_AM_QSORT_S) 77 #define CMP(t, x, y) (cmp((x), (y), (t))) 78 #else 79 #define CMP(t, x, y) (cmp((x), (y))) 80 #endif 81 82 static inline char * 83 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk 84 #if !defined(I_AM_QSORT_R) && !defined(I_AM_QSORT_S) 85 __unused 86 #endif 87 ) 88 { 89 return CMP(thunk, a, b) < 0 ? 90 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a )) 91 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c )); 92 } 93 94 /* 95 * The actual qsort() implementation is static to avoid preemptible calls when 96 * recursing. Also give them different names for improved debugging. 97 */ 98 #if defined(I_AM_QSORT_R) 99 #define local_qsort local_qsort_r 100 #elif defined(I_AM_QSORT_S) 101 #define local_qsort local_qsort_s 102 #endif 103 static void 104 local_qsort(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk) 105 { 106 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 107 size_t d1, d2; 108 int cmp_result; 109 int swap_cnt; 110 111 loop: 112 swap_cnt = 0; 113 if (n < 7) { 114 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 115 for (pl = pm; 116 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 117 pl -= es) 118 swapfunc(pl, pl - es, es); 119 return; 120 } 121 pm = (char *)a + (n / 2) * es; 122 if (n > 7) { 123 pl = a; 124 pn = (char *)a + (n - 1) * es; 125 if (n > 40) { 126 size_t d = (n / 8) * es; 127 128 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); 129 pm = med3(pm - d, pm, pm + d, cmp, thunk); 130 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); 131 } 132 pm = med3(pl, pm, pn, cmp, thunk); 133 } 134 swapfunc(a, pm, es); 135 pa = pb = (char *)a + es; 136 137 pc = pd = (char *)a + (n - 1) * es; 138 for (;;) { 139 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) { 140 if (cmp_result == 0) { 141 swap_cnt = 1; 142 swapfunc(pa, pb, es); 143 pa += es; 144 } 145 pb += es; 146 } 147 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) { 148 if (cmp_result == 0) { 149 swap_cnt = 1; 150 swapfunc(pc, pd, es); 151 pd -= es; 152 } 153 pc -= es; 154 } 155 if (pb > pc) 156 break; 157 swapfunc(pb, pc, es); 158 swap_cnt = 1; 159 pb += es; 160 pc -= es; 161 } 162 if (swap_cnt == 0) { /* Switch to insertion sort */ 163 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 164 for (pl = pm; 165 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 166 pl -= es) 167 swapfunc(pl, pl - es, es); 168 return; 169 } 170 171 pn = (char *)a + n * es; 172 d1 = MIN(pa - (char *)a, pb - pa); 173 vecswap(a, pb - d1, d1); 174 /* 175 * Cast es to preserve signedness of right-hand side of MIN() 176 * expression, to avoid sign ambiguity in the implied comparison. es 177 * is safely within [0, SSIZE_MAX]. 178 */ 179 d1 = MIN(pd - pc, pn - pd - (ssize_t)es); 180 vecswap(pb, pn - d1, d1); 181 182 d1 = pb - pa; 183 d2 = pd - pc; 184 if (d1 <= d2) { 185 /* Recurse on left partition, then iterate on right partition */ 186 if (d1 > es) { 187 local_qsort(a, d1 / es, es, cmp, thunk); 188 } 189 if (d2 > es) { 190 /* Iterate rather than recurse to save stack space */ 191 /* qsort(pn - d2, d2 / es, es, cmp); */ 192 a = pn - d2; 193 n = d2 / es; 194 goto loop; 195 } 196 } else { 197 /* Recurse on right partition, then iterate on left partition */ 198 if (d2 > es) { 199 local_qsort(pn - d2, d2 / es, es, cmp, thunk); 200 } 201 if (d1 > es) { 202 /* Iterate rather than recurse to save stack space */ 203 /* qsort(a, d1 / es, es, cmp); */ 204 n = d1 / es; 205 goto loop; 206 } 207 } 208 } 209 210 #if defined(I_AM_QSORT_R) 211 void 212 qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) 213 { 214 local_qsort_r(a, n, es, cmp, thunk); 215 } 216 #elif defined(I_AM_QSORT_S) 217 errno_t 218 qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk) 219 { 220 if (n > RSIZE_MAX) { 221 __throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL); 222 return (EINVAL); 223 } else if (es > RSIZE_MAX) { 224 __throw_constraint_handler_s("qsort_s : es > RSIZE_MAX", 225 EINVAL); 226 return (EINVAL); 227 } else if (n != 0) { 228 if (a == NULL) { 229 __throw_constraint_handler_s("qsort_s : a == NULL", 230 EINVAL); 231 return (EINVAL); 232 } else if (cmp == NULL) { 233 __throw_constraint_handler_s("qsort_s : cmp == NULL", 234 EINVAL); 235 return (EINVAL); 236 } 237 } 238 239 local_qsort_s(a, n, es, cmp, thunk); 240 return (0); 241 } 242 #else 243 void 244 qsort(void *a, size_t n, size_t es, cmp_t *cmp) 245 { 246 local_qsort(a, n, es, cmp, NULL); 247 } 248 #endif 249