qsort.c (5412B)
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 #include <stdlib.h> 35 36 #ifdef I_AM_QSORT_R 37 typedef int cmp_t(void *, const void *, const void *); 38 #else 39 typedef int cmp_t(const void *, const void *); 40 #endif 41 static inline char *med3(char *, char *, char *, cmp_t *, void *); 42 static inline void swapfunc(char *, char *, int, int); 43 44 #define min(a, b) (a) < (b) ? a : b 45 46 /* 47 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 48 */ 49 #define swapcode(TYPE, parmi, parmj, n) { \ 50 long i = (n) / sizeof (TYPE); \ 51 TYPE *pi = (TYPE *) (parmi); \ 52 TYPE *pj = (TYPE *) (parmj); \ 53 do { \ 54 TYPE t = *pi; \ 55 *pi++ = *pj; \ 56 *pj++ = t; \ 57 } while (--i > 0); \ 58 } 59 60 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 61 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 62 63 static inline void 64 swapfunc(a, b, n, swaptype) 65 char *a, *b; 66 int n, swaptype; 67 { 68 if(swaptype <= 1) 69 swapcode(long, a, b, n) 70 else 71 swapcode(char, a, b, n) 72 } 73 74 #define swap(a, b) \ 75 if (swaptype == 0) { \ 76 long t = *(long *)(a); \ 77 *(long *)(a) = *(long *)(b); \ 78 *(long *)(b) = t; \ 79 } else \ 80 swapfunc(a, b, es, swaptype) 81 82 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) 83 84 #ifdef I_AM_QSORT_R 85 #define CMP(t, x, y) (cmp((t), (x), (y))) 86 #else 87 #define CMP(t, x, y) (cmp((x), (y))) 88 #endif 89 90 static inline char * 91 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk 92 #ifndef I_AM_QSORT_R 93 __attribute__((__unused__)) 94 #endif 95 ) 96 { 97 return CMP(thunk, a, b) < 0 ? 98 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a )) 99 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c )); 100 } 101 102 #ifdef I_AM_QSORT_R 103 void 104 qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) 105 #else 106 #define thunk NULL 107 void 108 qsort(void *a, size_t n, size_t es, cmp_t *cmp) 109 #endif 110 { 111 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 112 int d, r, swaptype, swap_cnt; 113 114 loop: SWAPINIT(a, es); 115 swap_cnt = 0; 116 if (n < 7) { 117 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) 118 for (pl = pm; 119 pl > (char *)a && CMP(thunk, pl - es, pl) > 0; 120 pl -= es) 121 swap(pl, pl - es); 122 return; 123 } 124 pm = (char *)a + (n / 2) * es; 125 if (n > 7) { 126 pl = a; 127 pn = (char *)a + (n - 1) * es; 128 if (n > 40) { 129 d = (n / 8) * es; 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 swap(a, pm); 137 pa = pb = (char *)a + es; 138 139 pc = pd = (char *)a + (n - 1) * es; 140 for (;;) { 141 while (pb <= pc && (r = CMP(thunk, pb, a)) <= 0) { 142 if (r == 0) { 143 swap_cnt = 1; 144 swap(pa, pb); 145 pa += es; 146 } 147 pb += es; 148 } 149 while (pb <= pc && (r = CMP(thunk, pc, a)) >= 0) { 150 if (r == 0) { 151 swap_cnt = 1; 152 swap(pc, pd); 153 pd -= es; 154 } 155 pc -= es; 156 } 157 if (pb > pc) 158 break; 159 swap(pb, pc); 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 swap(pl, pl - es); 170 return; 171 } 172 173 pn = (char *)a + n * es; 174 r = min(pa - (char *)a, pb - pa); 175 vecswap(a, pb - r, r); 176 r = min(pd - pc, pn - pd - es); 177 vecswap(pb, pn - r, r); 178 if ((r = pb - pa) > es) 179 #ifdef I_AM_QSORT_R 180 qsort_r(a, r / es, es, thunk, cmp); 181 #else 182 qsort(a, r / es, es, cmp); 183 #endif 184 if ((r = pd - pc) > es) { 185 /* Iterate rather than recurse to save stack space */ 186 a = pn - r; 187 n = r / es; 188 goto loop; 189 } 190 /* qsort(pn - r, r / es, es, cmp);*/ 191 }