| 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 | } |