| 1 | /*-
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| 2 | * Copyright (c) 1992, 1993
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| 3 | * The Regents of the University of California. All rights reserved.
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| 4 | *
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| 5 | * This code is derived from software contributed to Berkeley by
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| 6 | * Peter McIlroy.
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| 7 | *
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| 8 | * Redistribution and use in source and binary forms, with or without
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| 9 | * modification, are permitted provided that the following conditions
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| 10 | * are met:
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| 11 | * 1. Redistributions of source code must retain the above copyright
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| 12 | * notice, this list of conditions and the following disclaimer.
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| 13 | * 2. Redistributions in binary form must reproduce the above copyright
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| 14 | * notice, this list of conditions and the following disclaimer in the
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| 15 | * documentation and/or other materials provided with the distribution.
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| 16 | * 3. All advertising materials mentioning features or use of this software
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| 17 | * must display the following acknowledgement:
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| 18 | * This product includes software developed by the University of
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| 19 | * California, Berkeley and its contributors.
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| 20 | * 4. Neither the name of the University nor the names of its contributors
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| 21 | * may be used to endorse or promote products derived from this software
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| 22 | * without specific prior written permission.
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| 23 | *
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| 24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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| 25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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| 26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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| 27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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| 28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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| 29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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| 30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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| 31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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| 32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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| 33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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| 34 | * SUCH DAMAGE.
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| 35 | */
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| 36 |
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| 37 | #if defined(LIBC_SCCS) && !defined(lint)
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| 38 | static char sccsid[] = "@(#)merge.c 8.2 (Berkeley) 2/14/94";
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| 39 | #endif /* LIBC_SCCS and not lint */
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| 40 | #include <sys/cdefs.h>
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| 41 | __FBSDID("$FreeBSD: src/lib/libc/stdlib/merge.c,v 1.6 2002/03/21 22:48:42 obrien Exp $");
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| 42 |
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| 43 | /*
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| 44 | * Hybrid exponential search/linear search merge sort with hybrid
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| 45 | * natural/pairwise first pass. Requires about .3% more comparisons
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| 46 | * for random data than LSMS with pairwise first pass alone.
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| 47 | * It works for objects as small as two bytes.
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| 48 | */
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| 49 |
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| 50 | #define NATURAL
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| 51 | #define THRESHOLD 16 /* Best choice for natural merge cut-off. */
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| 52 |
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| 53 | /* #define NATURAL to get hybrid natural merge.
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| 54 | * (The default is pairwise merging.)
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| 55 | */
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| 56 |
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| 57 | #include <sys/types.h>
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| 58 |
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| 59 | #include <errno.h>
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| 60 | #include <stdlib.h>
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| 61 | #include <string.h>
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| 62 |
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| 63 | static void setup(u_char *, u_char *, size_t, size_t, int (*)());
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| 64 | static void insertionsort(u_char *, size_t, size_t, int (*)());
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| 65 |
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| 66 | #define ISIZE sizeof(int)
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| 67 | #define PSIZE sizeof(u_char *)
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| 68 | #define ICOPY_LIST(src, dst, last) \
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| 69 | do \
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| 70 | *(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE; \
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| 71 | while(src < last)
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| 72 | #define ICOPY_ELT(src, dst, i) \
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| 73 | do \
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| 74 | *(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE; \
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| 75 | while (i -= ISIZE)
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| 76 |
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| 77 | #define CCOPY_LIST(src, dst, last) \
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| 78 | do \
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| 79 | *dst++ = *src++; \
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| 80 | while (src < last)
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| 81 | #define CCOPY_ELT(src, dst, i) \
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| 82 | do \
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| 83 | *dst++ = *src++; \
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| 84 | while (i -= 1)
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| 85 |
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| 86 | /*
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| 87 | * Find the next possible pointer head. (Trickery for forcing an array
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| 88 | * to do double duty as a linked list when objects do not align with word
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| 89 | * boundaries.
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| 90 | */
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| 91 | /* Assumption: PSIZE is a power of 2. */
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| 92 | #define EVAL(p) (u_char **) \
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| 93 | ((u_char *)0 + \
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| 94 | (((u_char *)p + PSIZE - 1 - (u_char *) 0) & ~(PSIZE - 1)))
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| 95 |
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| 96 | /*
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| 97 | * Arguments are as for qsort.
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| 98 | */
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| 99 | int
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| 100 | mergesort(base, nmemb, size, cmp)
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| 101 | void *base;
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| 102 | size_t nmemb;
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| 103 | size_t size;
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| 104 | int (*cmp)(const void *, const void *);
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| 105 | {
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| 106 | int i, sense;
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| 107 | int big, iflag;
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| 108 | u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2;
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| 109 | u_char *list2, *list1, *p2, *p, *last, **p1;
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| 110 |
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| 111 | if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */
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| 112 | errno = EINVAL;
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| 113 | return (-1);
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| 114 | }
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| 115 |
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| 116 | if (nmemb == 0)
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| 117 | return (0);
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| 118 |
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| 119 | /*
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| 120 | * XXX
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| 121 | * Stupid subtraction for the Cray.
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| 122 | */
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| 123 | iflag = 0;
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| 124 | if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE))
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| 125 | iflag = 1;
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| 126 |
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| 127 | if ((list2 = malloc(nmemb * size + PSIZE)) == NULL)
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| 128 | return (-1);
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| 129 |
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| 130 | list1 = base;
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| 131 | setup(list1, list2, nmemb, size, cmp);
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| 132 | last = list2 + nmemb * size;
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| 133 | i = big = 0;
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| 134 | while (*EVAL(list2) != last) {
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| 135 | l2 = list1;
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| 136 | p1 = EVAL(list1);
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| 137 | for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) {
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| 138 | p2 = *EVAL(p2);
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| 139 | f1 = l2;
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| 140 | f2 = l1 = list1 + (p2 - list2);
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| 141 | if (p2 != last)
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| 142 | p2 = *EVAL(p2);
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| 143 | l2 = list1 + (p2 - list2);
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| 144 | while (f1 < l1 && f2 < l2) {
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| 145 | if ((*cmp)(f1, f2) <= 0) {
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| 146 | q = f2;
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| 147 | b = f1, t = l1;
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| 148 | sense = -1;
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| 149 | } else {
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| 150 | q = f1;
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| 151 | b = f2, t = l2;
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| 152 | sense = 0;
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| 153 | }
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| 154 | if (!big) { /* here i = 0 */
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| 155 | while ((b += size) < t && cmp(q, b) >sense)
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| 156 | if (++i == 6) {
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| 157 | big = 1;
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| 158 | goto EXPONENTIAL;
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| 159 | }
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| 160 | } else {
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| 161 | EXPONENTIAL: for (i = size; ; i <<= 1)
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| 162 | if ((p = (b + i)) >= t) {
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| 163 | if ((p = t - size) > b &&
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| 164 | (*cmp)(q, p) <= sense)
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| 165 | t = p;
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| 166 | else
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| 167 | b = p;
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| 168 | break;
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| 169 | } else if ((*cmp)(q, p) <= sense) {
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| 170 | t = p;
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| 171 | if (i == size)
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| 172 | big = 0;
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| 173 | goto FASTCASE;
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| 174 | } else
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| 175 | b = p;
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| 176 | while (t > b+size) {
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| 177 | i = (((t - b) / size) >> 1) * size;
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| 178 | if ((*cmp)(q, p = b + i) <= sense)
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| 179 | t = p;
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| 180 | else
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| 181 | b = p;
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| 182 | }
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| 183 | goto COPY;
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| 184 | FASTCASE: while (i > size)
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| 185 | if ((*cmp)(q,
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| 186 | p = b + (i >>= 1)) <= sense)
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| 187 | t = p;
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| 188 | else
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| 189 | b = p;
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| 190 | COPY: b = t;
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| 191 | }
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| 192 | i = size;
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| 193 | if (q == f1) {
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| 194 | if (iflag) {
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| 195 | ICOPY_LIST(f2, tp2, b);
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| 196 | ICOPY_ELT(f1, tp2, i);
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| 197 | } else {
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| 198 | CCOPY_LIST(f2, tp2, b);
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| 199 | CCOPY_ELT(f1, tp2, i);
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| 200 | }
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| 201 | } else {
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| 202 | if (iflag) {
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| 203 | ICOPY_LIST(f1, tp2, b);
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| 204 | ICOPY_ELT(f2, tp2, i);
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| 205 | } else {
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| 206 | CCOPY_LIST(f1, tp2, b);
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| 207 | CCOPY_ELT(f2, tp2, i);
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| 208 | }
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| 209 | }
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| 210 | }
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| 211 | if (f2 < l2) {
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| 212 | if (iflag)
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| 213 | ICOPY_LIST(f2, tp2, l2);
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| 214 | else
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| 215 | CCOPY_LIST(f2, tp2, l2);
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| 216 | } else if (f1 < l1) {
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| 217 | if (iflag)
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| 218 | ICOPY_LIST(f1, tp2, l1);
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| 219 | else
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| 220 | CCOPY_LIST(f1, tp2, l1);
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| 221 | }
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| 222 | *p1 = l2;
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| 223 | }
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| 224 | tp2 = list1; /* swap list1, list2 */
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| 225 | list1 = list2;
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| 226 | list2 = tp2;
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| 227 | last = list2 + nmemb*size;
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| 228 | }
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| 229 | if (base == list2) {
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| 230 | memmove(list2, list1, nmemb*size);
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| 231 | list2 = list1;
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| 232 | }
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| 233 | free(list2);
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| 234 | return (0);
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| 235 | }
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| 236 |
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| 237 | #define swap(a, b) { \
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| 238 | s = b; \
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| 239 | i = size; \
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| 240 | do { \
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| 241 | tmp = *a; *a++ = *s; *s++ = tmp; \
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| 242 | } while (--i); \
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| 243 | a -= size; \
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| 244 | }
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| 245 | #define reverse(bot, top) { \
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| 246 | s = top; \
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| 247 | do { \
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| 248 | i = size; \
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| 249 | do { \
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| 250 | tmp = *bot; *bot++ = *s; *s++ = tmp; \
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| 251 | } while (--i); \
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| 252 | s -= size2; \
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| 253 | } while(bot < s); \
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| 254 | }
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| 255 |
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| 256 | /*
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| 257 | * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of
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| 258 | * increasing order, list2 in a corresponding linked list. Checks for runs
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| 259 | * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL
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| 260 | * is defined. Otherwise simple pairwise merging is used.)
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| 261 | */
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| 262 | void
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| 263 | setup(list1, list2, n, size, cmp)
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| 264 | size_t n, size;
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| 265 | int (*cmp)(const void *, const void *);
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| 266 | u_char *list1, *list2;
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| 267 | {
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| 268 | int i, length, size2, tmp, sense;
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| 269 | u_char *f1, *f2, *s, *l2, *last, *p2;
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| 270 |
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| 271 | size2 = size*2;
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| 272 | if (n <= 5) {
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| 273 | insertionsort(list1, n, size, cmp);
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| 274 | *EVAL(list2) = (u_char*) list2 + n*size;
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| 275 | return;
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| 276 | }
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| 277 | /*
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| 278 | * Avoid running pointers out of bounds; limit n to evens
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| 279 | * for simplicity.
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| 280 | */
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| 281 | i = 4 + (n & 1);
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| 282 | insertionsort(list1 + (n - i) * size, i, size, cmp);
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| 283 | last = list1 + size * (n - i);
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| 284 | *EVAL(list2 + (last - list1)) = list2 + n * size;
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| 285 |
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| 286 | #ifdef NATURAL
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| 287 | p2 = list2;
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| 288 | f1 = list1;
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| 289 | sense = (cmp(f1, f1 + size) > 0);
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| 290 | for (; f1 < last; sense = !sense) {
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| 291 | length = 2;
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| 292 | /* Find pairs with same sense. */
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| 293 | for (f2 = f1 + size2; f2 < last; f2 += size2) {
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| 294 | if ((cmp(f2, f2+ size) > 0) != sense)
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| 295 | break;
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| 296 | length += 2;
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| 297 | }
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| 298 | if (length < THRESHOLD) { /* Pairwise merge */
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| 299 | do {
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| 300 | p2 = *EVAL(p2) = f1 + size2 - list1 + list2;
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| 301 | if (sense > 0)
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| 302 | swap (f1, f1 + size);
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| 303 | } while ((f1 += size2) < f2);
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| 304 | } else { /* Natural merge */
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| 305 | l2 = f2;
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| 306 | for (f2 = f1 + size2; f2 < l2; f2 += size2) {
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| 307 | if ((cmp(f2-size, f2) > 0) != sense) {
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| 308 | p2 = *EVAL(p2) = f2 - list1 + list2;
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| 309 | if (sense > 0)
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| 310 | reverse(f1, f2-size);
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| 311 | f1 = f2;
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| 312 | }
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| 313 | }
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| 314 | if (sense > 0)
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| 315 | reverse (f1, f2-size);
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| 316 | f1 = f2;
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| 317 | if (f2 < last || cmp(f2 - size, f2) > 0)
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| 318 | p2 = *EVAL(p2) = f2 - list1 + list2;
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| 319 | else
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| 320 | p2 = *EVAL(p2) = list2 + n*size;
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| 321 | }
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| 322 | }
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| 323 | #else /* pairwise merge only. */
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| 324 | for (f1 = list1, p2 = list2; f1 < last; f1 += size2) {
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| 325 | p2 = *EVAL(p2) = p2 + size2;
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| 326 | if (cmp (f1, f1 + size) > 0)
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| 327 | swap(f1, f1 + size);
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| 328 | }
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| 329 | #endif /* NATURAL */
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| 330 | }
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| 331 |
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| 332 | /*
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| 333 | * This is to avoid out-of-bounds addresses in sorting the
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| 334 | * last 4 elements.
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| 335 | */
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| 336 | static void
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| 337 | insertionsort(a, n, size, cmp)
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| 338 | u_char *a;
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| 339 | size_t n, size;
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| 340 | int (*cmp)(const void *, const void *);
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| 341 | {
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| 342 | u_char *ai, *s, *t, *u, tmp;
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| 343 | int i;
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| 344 |
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| 345 | for (ai = a+size; --n >= 1; ai += size)
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| 346 | for (t = ai; t > a; t -= size) {
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| 347 | u = t - size;
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| 348 | if (cmp(u, t) <= 0)
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| 349 | break;
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| 350 | swap(u, t);
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| 351 | }
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| 352 | }
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