1 /*- 2 * Copyright (c) 1992, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #if defined(LIBC_SCCS) && !defined(lint) 35 #if 0 36 static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93"; 37 #endif 38 static const char rcsid[] = 39 "$Id$"; 40 #endif /* LIBC_SCCS and not lint */ 41 42 #include <sys/types.h> 43 #include <stdlib.h> 44 45 typedef int cmp_t __P((const void *, const void *)); 46 static inline char *med3 __P((char *, char *, char *, cmp_t *)); 47 static inline void swapfunc __P((char *, char *, int, int)); 48 49 #define min(a, b) (a) < (b) ? a : b 50 51 /* 52 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 53 */ 54 #define swapcode(TYPE, parmi, parmj, n) { \ 55 long i = (n) / sizeof (TYPE); \ 56 register TYPE *pi = (TYPE *) (parmi); \ 57 register TYPE *pj = (TYPE *) (parmj); \ 58 do { \ 59 register TYPE t = *pi; \ 60 *pi++ = *pj; \ 61 *pj++ = t; \ 62 } while (--i > 0); \ 63 } 64 65 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 66 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 67 68 static inline void 69 swapfunc(a, b, n, swaptype) 70 char *a, *b; 71 int n, swaptype; 72 { 73 if(swaptype <= 1) 74 swapcode(long, a, b, n) 75 else 76 swapcode(char, a, b, n) 77 } 78 79 #define swap(a, b) \ 80 if (swaptype == 0) { \ 81 long t = *(long *)(a); \ 82 *(long *)(a) = *(long *)(b); \ 83 *(long *)(b) = t; \ 84 } else \ 85 swapfunc(a, b, es, swaptype) 86 87 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) 88 89 static inline char * 90 med3(a, b, c, cmp) 91 char *a, *b, *c; 92 cmp_t *cmp; 93 { 94 return cmp(a, b) < 0 ? 95 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) 96 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); 97 } 98 99 void 100 qsort(a, n, es, cmp) 101 void *a; 102 size_t n, es; 103 cmp_t *cmp; 104 { 105 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 106 int d, r, swaptype, swap_cnt; 107 108 loop: SWAPINIT(a, es); 109 swap_cnt = 0; 110 if (n < 7) { 111 for (pm = a + es; pm < (char *) a + n * es; pm += es) 112 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 113 pl -= es) 114 swap(pl, pl - es); 115 return; 116 } 117 pm = a + (n / 2) * es; 118 if (n > 7) { 119 pl = a; 120 pn = a + (n - 1) * es; 121 if (n > 40) { 122 d = (n / 8) * es; 123 pl = med3(pl, pl + d, pl + 2 * d, cmp); 124 pm = med3(pm - d, pm, pm + d, cmp); 125 pn = med3(pn - 2 * d, pn - d, pn, cmp); 126 } 127 pm = med3(pl, pm, pn, cmp); 128 } 129 swap(a, pm); 130 pa = pb = a + es; 131 132 pc = pd = a + (n - 1) * es; 133 for (;;) { 134 while (pb <= pc && (r = cmp(pb, a)) <= 0) { 135 if (r == 0) { 136 swap_cnt = 1; 137 swap(pa, pb); 138 pa += es; 139 } 140 pb += es; 141 } 142 while (pb <= pc && (r = cmp(pc, a)) >= 0) { 143 if (r == 0) { 144 swap_cnt = 1; 145 swap(pc, pd); 146 pd -= es; 147 } 148 pc -= es; 149 } 150 if (pb > pc) 151 break; 152 swap(pb, pc); 153 swap_cnt = 1; 154 pb += es; 155 pc -= es; 156 } 157 if (swap_cnt == 0) { /* Switch to insertion sort */ 158 for (pm = a + es; pm < (char *) a + n * es; pm += es) 159 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 160 pl -= es) 161 swap(pl, pl - es); 162 return; 163 } 164 165 pn = a + n * es; 166 r = min(pa - (char *)a, pb - pa); 167 vecswap(a, pb - r, r); 168 r = min(pd - pc, pn - pd - es); 169 vecswap(pb, pn - r, r); 170 if ((r = pb - pa) > es) 171 qsort(a, r / es, es, cmp); 172 if ((r = pd - pc) > es) { 173 /* Iterate rather than recurse to save stack space */ 174 a = pn - r; 175 n = r / es; 176 goto loop; 177 } 178 /* qsort(pn - r, r / es, es, cmp);*/ 179 } 180