1 /* The following is the NetBSD libc qsort implementation modified in order to 2 * support partial sorting of ranges for Redis. 3 * 4 * Copyright(C) 2009-2010 Salvatore Sanfilippo. All rights reserved. 5 * 6 * The original copyright notice follows. */ 7 8 9 /* $NetBSD: qsort.c,v 1.19 2009/01/30 23:38:44 lukem Exp $ */ 10 11 /*- 12 * Copyright (c) 1992, 1993 13 * The Regents of the University of California. All rights reserved. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 3. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 */ 39 40 #include <sys/types.h> 41 42 #include <assert.h> 43 #include <errno.h> 44 #include <stdlib.h> 45 46 static inline char *med3 (char *, char *, char *, 47 int (*)(const void *, const void *)); 48 static inline void swapfunc (char *, char *, size_t, int); 49 50 #define min(a, b) (a) < (b) ? a : b 51 52 /* 53 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". 54 */ 55 #define swapcode(TYPE, parmi, parmj, n) { \ 56 size_t i = (n) / sizeof (TYPE); \ 57 TYPE *pi = (TYPE *)(void *)(parmi); \ 58 TYPE *pj = (TYPE *)(void *)(parmj); \ 59 do { \ 60 TYPE t = *pi; \ 61 *pi++ = *pj; \ 62 *pj++ = t; \ 63 } while (--i > 0); \ 64 } 65 66 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ 67 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; 68 69 static inline void 70 swapfunc(char *a, char *b, size_t n, int swaptype) 71 { 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 *)(void *)(a); \ 82 *(long *)(void *)(a) = *(long *)(void *)(b); \ 83 *(long *)(void *)(b) = t; \ 84 } else \ 85 swapfunc(a, b, es, swaptype) 86 87 #define vecswap(a, b, n) if ((n) > 0) swapfunc((a), (b), (size_t)(n), swaptype) 88 89 static inline char * 90 med3(char *a, char *b, char *c, 91 int (*cmp) (const void *, const void *)) 92 { 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 static void 100 _pqsort(void *a, size_t n, size_t es, 101 int (*cmp) (const void *, const void *), void *lrange, void *rrange) 102 { 103 char *pa, *pb, *pc, *pd, *pl, *pm, *pn; 104 size_t d, r; 105 int swaptype, swap_cnt, cmp_result; 106 107 loop: SWAPINIT(a, es); 108 swap_cnt = 0; 109 if (n < 7) { 110 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) 111 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 112 pl -= es) 113 swap(pl, pl - es); 114 return; 115 } 116 pm = (char *) a + (n / 2) * es; 117 if (n > 7) { 118 pl = (char *) a; 119 pn = (char *) a + (n - 1) * es; 120 if (n > 40) { 121 d = (n / 8) * es; 122 pl = med3(pl, pl + d, pl + 2 * d, cmp); 123 pm = med3(pm - d, pm, pm + d, cmp); 124 pn = med3(pn - 2 * d, pn - d, pn, cmp); 125 } 126 pm = med3(pl, pm, pn, cmp); 127 } 128 swap(a, pm); 129 pa = pb = (char *) a + es; 130 131 pc = pd = (char *) a + (n - 1) * es; 132 for (;;) { 133 while (pb <= pc && (cmp_result = cmp(pb, a)) <= 0) { 134 if (cmp_result == 0) { 135 swap_cnt = 1; 136 swap(pa, pb); 137 pa += es; 138 } 139 pb += es; 140 } 141 while (pb <= pc && (cmp_result = cmp(pc, a)) >= 0) { 142 if (cmp_result == 0) { 143 swap_cnt = 1; 144 swap(pc, pd); 145 pd -= es; 146 } 147 pc -= es; 148 } 149 if (pb > pc) 150 break; 151 swap(pb, pc); 152 swap_cnt = 1; 153 pb += es; 154 pc -= es; 155 } 156 if (swap_cnt == 0) { /* Switch to insertion sort */ 157 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) 158 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; 159 pl -= es) 160 swap(pl, pl - es); 161 return; 162 } 163 164 pn = (char *) a + n * es; 165 r = min(pa - (char *) a, pb - pa); 166 vecswap(a, pb - r, r); 167 r = min((size_t)(pd - pc), pn - pd - es); 168 vecswap(pb, pn - r, r); 169 if ((r = pb - pa) > es) { 170 void *_l = a, *_r = ((unsigned char*)a)+r-1; 171 if (!((lrange < _l && rrange < _l) || 172 (lrange > _r && rrange > _r))) 173 _pqsort(a, r / es, es, cmp, lrange, rrange); 174 } 175 if ((r = pd - pc) > es) { 176 void *_l, *_r; 177 178 /* Iterate rather than recurse to save stack space */ 179 a = pn - r; 180 n = r / es; 181 182 _l = a; 183 _r = ((unsigned char*)a)+r-1; 184 if (!((lrange < _l && rrange < _l) || 185 (lrange > _r && rrange > _r))) 186 goto loop; 187 } 188 /* qsort(pn - r, r / es, es, cmp);*/ 189 } 190 191 void 192 pqsort(void *a, size_t n, size_t es, 193 int (*cmp) (const void *, const void *), size_t lrange, size_t rrange) 194 { 195 _pqsort(a,n,es,cmp,((unsigned char*)a)+(lrange*es), 196 ((unsigned char*)a)+((rrange+1)*es)-1); 197 } 198