43fa6fe319
identifier namespace by renaming non standard functions and variables such that they have a leading underscore. The library will use those names internally. Weak aliases are used to provide the original names to the API. This is only the first part of this change. It is most of the functions which are implemented in C for all NetBSD ports. Subsequent changes are to add the same support to the remaining C files, to assembly files, and to the automagically generated assembly source used for system calls. When all of the above is done, ports with weak alias support should add a definition for __weak_alias to <sys/cdefs.h>.
368 lines
9.5 KiB
C
368 lines
9.5 KiB
C
/* $NetBSD: merge.c,v 1.5 1997/07/21 14:08:56 jtc Exp $ */
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/*-
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* Copyright (c) 1992, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Peter McIlroy.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#if defined(LIBC_SCCS) && !defined(lint)
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#if 0
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static char sccsid[] = "from: @(#)merge.c 8.2 (Berkeley) 2/14/94";
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#else
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__RCSID("$NetBSD: merge.c,v 1.5 1997/07/21 14:08:56 jtc Exp $");
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#endif
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#endif /* LIBC_SCCS and not lint */
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/*
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* Hybrid exponential search/linear search merge sort with hybrid
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* natural/pairwise first pass. Requires about .3% more comparisons
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* for random data than LSMS with pairwise first pass alone.
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* It works for objects as small as two bytes.
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*/
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#define NATURAL
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#define THRESHOLD 16 /* Best choice for natural merge cut-off. */
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/* #define NATURAL to get hybrid natural merge.
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* (The default is pairwise merging.)
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*/
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#include "namespace.h"
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#include <sys/types.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#ifdef __weak_alias
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__weak_alias(mergesort,_mergesort);
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#endif
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static void setup __P((u_char *, u_char *, size_t, size_t,
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int (*)(const void *, const void *)));
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static void insertionsort __P((u_char *, size_t, size_t,
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int (*)(const void *, const void *)));
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#define ISIZE sizeof(int)
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#define PSIZE sizeof(u_char *)
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#define ICOPY_LIST(src, dst, last) \
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do \
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*(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE; \
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while(src < last)
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#define ICOPY_ELT(src, dst, i) \
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do \
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*(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE; \
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while (i -= ISIZE)
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#define CCOPY_LIST(src, dst, last) \
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do \
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*dst++ = *src++; \
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while (src < last)
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#define CCOPY_ELT(src, dst, i) \
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do \
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*dst++ = *src++; \
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while (i -= 1)
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/*
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* Find the next possible pointer head. (Trickery for forcing an array
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* to do double duty as a linked list when objects do not align with word
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* boundaries.
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*/
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/* Assumption: PSIZE is a power of 2. */
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#define EVAL(p) (u_char **) \
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((u_char *)0 + \
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(((u_char *)p + PSIZE - 1 - (u_char *) 0) & ~(PSIZE - 1)))
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/*
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* Arguments are as for qsort.
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*/
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int
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mergesort(base, nmemb, size, cmp)
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void *base;
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size_t nmemb;
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register size_t size;
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int (*cmp) __P((const void *, const void *));
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{
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register int i, sense;
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int big, iflag;
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register u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2;
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u_char *list2, *list1, *p2, *p, *last, **p1;
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if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */
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errno = EINVAL;
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return (-1);
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}
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/*
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* XXX
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* Stupid subtraction for the Cray.
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*/
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iflag = 0;
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if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE))
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iflag = 1;
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if ((list2 = malloc(nmemb * size + PSIZE)) == NULL)
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return (-1);
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list1 = base;
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setup(list1, list2, nmemb, size, cmp);
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last = list2 + nmemb * size;
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i = big = 0;
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while (*EVAL(list2) != last) {
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l2 = list1;
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p1 = EVAL(list1);
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for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) {
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p2 = *EVAL(p2);
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f1 = l2;
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f2 = l1 = list1 + (p2 - list2);
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if (p2 != last)
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p2 = *EVAL(p2);
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l2 = list1 + (p2 - list2);
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while (f1 < l1 && f2 < l2) {
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if ((*cmp)(f1, f2) <= 0) {
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q = f2;
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b = f1, t = l1;
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sense = -1;
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} else {
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q = f1;
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b = f2, t = l2;
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sense = 0;
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}
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if (!big) { /* here i = 0 */
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#if 0
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LINEAR:
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#endif
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while ((b += size) < t && cmp(q, b) >sense)
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if (++i == 6) {
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big = 1;
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goto EXPONENTIAL;
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}
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} else {
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EXPONENTIAL: for (i = size; ; i <<= 1)
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if ((p = (b + i)) >= t) {
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if ((p = t - size) > b &&
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(*cmp)(q, p) <= sense)
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t = p;
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else
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b = p;
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break;
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} else if ((*cmp)(q, p) <= sense) {
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t = p;
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if (i == size)
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big = 0;
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goto FASTCASE;
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} else
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b = p;
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#if 0
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SLOWCASE:
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#endif
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while (t > b+size) {
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i = (((t - b) / size) >> 1) * size;
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if ((*cmp)(q, p = b + i) <= sense)
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t = p;
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else
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b = p;
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}
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goto COPY;
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FASTCASE: while (i > size)
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if ((*cmp)(q,
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p = b + (i >>= 1)) <= sense)
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t = p;
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else
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b = p;
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COPY: b = t;
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}
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i = size;
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if (q == f1) {
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if (iflag) {
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ICOPY_LIST(f2, tp2, b);
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ICOPY_ELT(f1, tp2, i);
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} else {
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CCOPY_LIST(f2, tp2, b);
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CCOPY_ELT(f1, tp2, i);
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}
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} else {
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if (iflag) {
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ICOPY_LIST(f1, tp2, b);
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ICOPY_ELT(f2, tp2, i);
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} else {
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CCOPY_LIST(f1, tp2, b);
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CCOPY_ELT(f2, tp2, i);
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}
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}
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}
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if (f2 < l2) {
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if (iflag)
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ICOPY_LIST(f2, tp2, l2);
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else
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CCOPY_LIST(f2, tp2, l2);
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} else if (f1 < l1) {
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if (iflag)
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ICOPY_LIST(f1, tp2, l1);
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else
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CCOPY_LIST(f1, tp2, l1);
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}
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*p1 = l2;
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}
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tp2 = list1; /* swap list1, list2 */
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list1 = list2;
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list2 = tp2;
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last = list2 + nmemb*size;
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}
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if (base == list2) {
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memmove(list2, list1, nmemb*size);
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list2 = list1;
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}
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free(list2);
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return (0);
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}
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#define swap(a, b) { \
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s = b; \
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i = size; \
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do { \
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tmp = *a; *a++ = *s; *s++ = tmp; \
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} while (--i); \
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a -= size; \
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}
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#define reverse(bot, top) { \
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s = top; \
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do { \
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i = size; \
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do { \
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tmp = *bot; *bot++ = *s; *s++ = tmp; \
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} while (--i); \
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s -= size2; \
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} while(bot < s); \
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}
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/*
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* Optional hybrid natural/pairwise first pass. Eats up list1 in runs of
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* increasing order, list2 in a corresponding linked list. Checks for runs
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* when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL
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* is defined. Otherwise simple pairwise merging is used.)
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*/
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void
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setup(list1, list2, n, size, cmp)
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size_t n, size;
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int (*cmp) __P((const void *, const void *));
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u_char *list1, *list2;
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{
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int i, length, size2, tmp, sense;
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u_char *f1, *f2, *s, *l2, *last, *p2;
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size2 = size*2;
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if (n <= 5) {
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insertionsort(list1, n, size, cmp);
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*EVAL(list2) = (u_char*) list2 + n*size;
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return;
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}
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/*
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* Avoid running pointers out of bounds; limit n to evens
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* for simplicity.
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*/
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i = 4 + (n & 1);
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insertionsort(list1 + (n - i) * size, i, size, cmp);
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last = list1 + size * (n - i);
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*EVAL(list2 + (last - list1)) = list2 + n * size;
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#ifdef NATURAL
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p2 = list2;
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f1 = list1;
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sense = (cmp(f1, f1 + size) > 0);
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for (; f1 < last; sense = !sense) {
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length = 2;
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/* Find pairs with same sense. */
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for (f2 = f1 + size2; f2 < last; f2 += size2) {
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if ((cmp(f2, f2+ size) > 0) != sense)
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break;
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length += 2;
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}
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if (length < THRESHOLD) { /* Pairwise merge */
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do {
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p2 = *EVAL(p2) = f1 + size2 - list1 + list2;
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if (sense > 0)
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swap (f1, f1 + size);
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} while ((f1 += size2) < f2);
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} else { /* Natural merge */
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l2 = f2;
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for (f2 = f1 + size2; f2 < l2; f2 += size2) {
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if ((cmp(f2-size, f2) > 0) != sense) {
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p2 = *EVAL(p2) = f2 - list1 + list2;
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if (sense > 0)
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reverse(f1, f2-size);
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f1 = f2;
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}
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}
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if (sense > 0)
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reverse (f1, f2-size);
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f1 = f2;
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if (f2 < last || cmp(f2 - size, f2) > 0)
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p2 = *EVAL(p2) = f2 - list1 + list2;
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else
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p2 = *EVAL(p2) = list2 + n*size;
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}
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}
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#else /* pairwise merge only. */
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for (f1 = list1, p2 = list2; f1 < last; f1 += size2) {
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p2 = *EVAL(p2) = p2 + size2;
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if (cmp (f1, f1 + size) > 0)
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swap(f1, f1 + size);
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}
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#endif /* NATURAL */
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}
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/*
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* This is to avoid out-of-bounds addresses in sorting the
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* last 4 elements.
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*/
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static void
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insertionsort(a, n, size, cmp)
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u_char *a;
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size_t n, size;
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int (*cmp) __P((const void *, const void *));
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{
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u_char *ai, *s, *t, *u, tmp;
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int i;
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for (ai = a+size; --n >= 1; ai += size)
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for (t = ai; t > a; t -= size) {
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u = t - size;
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if (cmp(u, t) <= 0)
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break;
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swap(u, t);
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}
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}
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