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 if (__predict_false(n == 0)) 112 return; 113 loop: 114 swap_cnt = 0; 115 if (n < 7) { 116 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 117 for (pl = pm; 118 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 119 pl -= es) 120 swapfunc(pl, pl - es, es); 121 return; 122 } 123 pm = (char *)a + (n / 2) * es; 124 if (n > 7) { 125 pl = a; 126 pn = (char *)a + (n - 1) * es; 127 if (n > 40) { 128 size_t d = (n / 8) * es; 129 130 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); 131 pm = med3(pm - d, pm, pm + d, cmp, thunk); 132 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); 133 } 134 pm = med3(pl, pm, pn, cmp, thunk); 135 } 136 swapfunc(a, pm, es); 137 pa = pb = (char *)a + es; 138 139 pc = pd = (char *)a + (n - 1) * es; 140 for (;;) { 141 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) { 142 if (cmp_result == 0) { 143 swap_cnt = 1; 144 swapfunc(pa, pb, es); 145 pa += es; 146 } 147 pb += es; 148 } 149 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) { 150 if (cmp_result == 0) { 151 swap_cnt = 1; 152 swapfunc(pc, pd, es); 153 pd -= es; 154 } 155 pc -= es; 156 } 157 if (pb > pc) 158 break; 159 swapfunc(pb, pc, es); 160 swap_cnt = 1; 161 pb += es; 162 pc -= es; 163 } 164 if (swap_cnt == 0) { /* Switch to insertion sort */ 165 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 166 for (pl = pm; 167 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 168 pl -= es) 169 swapfunc(pl, pl - es, es); 170 return; 171 } 172 173 pn = (char *)a + n * es; 174 d1 = MIN(pa - (char *)a, pb - pa); 175 vecswap(a, pb - d1, d1); 176 /* 177 * Cast es to preserve signedness of right-hand side of MIN() 178 * expression, to avoid sign ambiguity in the implied comparison. es 179 * is safely within [0, SSIZE_MAX]. 180 */ 181 d1 = MIN(pd - pc, pn - pd - (ssize_t)es); 182 vecswap(pb, pn - d1, d1); 183 184 d1 = pb - pa; 185 d2 = pd - pc; 186 if (d1 <= d2) { 187 /* Recurse on left partition, then iterate on right partition */ 188 if (d1 > es) { 189 local_qsort(a, d1 / es, es, cmp, thunk); 190 } 191 if (d2 > es) { 192 /* Iterate rather than recurse to save stack space */ 193 /* qsort(pn - d2, d2 / es, es, cmp); */ 194 a = pn - d2; 195 n = d2 / es; 196 goto loop; 197 } 198 } else { 199 /* Recurse on right partition, then iterate on left partition */ 200 if (d2 > es) { 201 local_qsort(pn - d2, d2 / es, es, cmp, thunk); 202 } 203 if (d1 > es) { 204 /* Iterate rather than recurse to save stack space */ 205 /* qsort(a, d1 / es, es, cmp); */ 206 n = d1 / es; 207 goto loop; 208 } 209 } 210 } 211 212 #if defined(I_AM_QSORT_R) 213 void 214 qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) 215 { 216 local_qsort_r(a, n, es, cmp, thunk); 217 } 218 #elif defined(I_AM_QSORT_S) 219 errno_t 220 qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk) 221 { 222 if (n > RSIZE_MAX) { 223 __throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL); 224 return (EINVAL); 225 } else if (es > RSIZE_MAX) { 226 __throw_constraint_handler_s("qsort_s : es > RSIZE_MAX", 227 EINVAL); 228 return (EINVAL); 229 } else if (n != 0) { 230 if (a == NULL) { 231 __throw_constraint_handler_s("qsort_s : a == NULL", 232 EINVAL); 233 return (EINVAL); 234 } else if (cmp == NULL) { 235 __throw_constraint_handler_s("qsort_s : cmp == NULL", 236 EINVAL); 237 return (EINVAL); 238 } 239 } 240 241 local_qsort_s(a, n, es, cmp, thunk); 242 return (0); 243 } 244 #else 245 void 246 qsort(void *a, size_t n, size_t es, cmp_t *cmp) 247 { 248 local_qsort(a, n, es, cmp, NULL); 249 } 250 #endif 251