freebsd-skq/lib/libc/stdlib/merge.c
Pedro F. Giffuni 8a16b7a18f General further adoption of SPDX licensing ID tags.
Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.
2017-11-20 19:49:47 +00:00

362 lines
9.3 KiB
C

/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Peter McIlroy.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)merge.c 8.2 (Berkeley) 2/14/94";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/*
* Hybrid exponential search/linear search merge sort with hybrid
* natural/pairwise first pass. Requires about .3% more comparisons
* for random data than LSMS with pairwise first pass alone.
* It works for objects as small as two bytes.
*/
#define NATURAL
#define THRESHOLD 16 /* Best choice for natural merge cut-off. */
/* #define NATURAL to get hybrid natural merge.
* (The default is pairwise merging.)
*/
#include <sys/types.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#ifdef I_AM_MERGESORT_B
#include "block_abi.h"
#define DECLARE_CMP DECLARE_BLOCK(int, cmp, const void *, const void *)
typedef DECLARE_BLOCK(int, cmp_t, const void *, const void *);
#define CMP(x, y) CALL_BLOCK(cmp, x, y)
#else
typedef int (*cmp_t)(const void *, const void *);
#define CMP(x, y) cmp(x, y)
#endif
static void setup(u_char *, u_char *, size_t, size_t, cmp_t);
static void insertionsort(u_char *, size_t, size_t, cmp_t);
#define ISIZE sizeof(int)
#define PSIZE sizeof(u_char *)
#define ICOPY_LIST(src, dst, last) \
do \
*(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE; \
while(src < last)
#define ICOPY_ELT(src, dst, i) \
do \
*(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE; \
while (i -= ISIZE)
#define CCOPY_LIST(src, dst, last) \
do \
*dst++ = *src++; \
while (src < last)
#define CCOPY_ELT(src, dst, i) \
do \
*dst++ = *src++; \
while (i -= 1)
/*
* Find the next possible pointer head. (Trickery for forcing an array
* to do double duty as a linked list when objects do not align with word
* boundaries.
*/
/* Assumption: PSIZE is a power of 2. */
#define EVAL(p) (u_char **) \
((u_char *)0 + \
(((u_char *)p + PSIZE - 1 - (u_char *) 0) & ~(PSIZE - 1)))
#ifdef I_AM_MERGESORT_B
int mergesort_b(void *, size_t, size_t, cmp_t);
#else
int mergesort(void *, size_t, size_t, cmp_t);
#endif
/*
* Arguments are as for qsort.
*/
int
#ifdef I_AM_MERGESORT_B
mergesort_b(void *base, size_t nmemb, size_t size, cmp_t cmp)
#else
mergesort(void *base, size_t nmemb, size_t size, cmp_t cmp)
#endif
{
size_t i;
int sense;
int big, iflag;
u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2;
u_char *list2, *list1, *p2, *p, *last, **p1;
if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */
errno = EINVAL;
return (-1);
}
if (nmemb == 0)
return (0);
/*
* XXX
* Stupid subtraction for the Cray.
*/
iflag = 0;
if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE))
iflag = 1;
if ((list2 = malloc(nmemb * size + PSIZE)) == NULL)
return (-1);
list1 = base;
setup(list1, list2, nmemb, size, cmp);
last = list2 + nmemb * size;
i = big = 0;
while (*EVAL(list2) != last) {
l2 = list1;
p1 = EVAL(list1);
for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) {
p2 = *EVAL(p2);
f1 = l2;
f2 = l1 = list1 + (p2 - list2);
if (p2 != last)
p2 = *EVAL(p2);
l2 = list1 + (p2 - list2);
while (f1 < l1 && f2 < l2) {
if (CMP(f1, f2) <= 0) {
q = f2;
b = f1, t = l1;
sense = -1;
} else {
q = f1;
b = f2, t = l2;
sense = 0;
}
if (!big) { /* here i = 0 */
while ((b += size) < t && CMP(q, b) >sense)
if (++i == 6) {
big = 1;
goto EXPONENTIAL;
}
} else {
EXPONENTIAL: for (i = size; ; i <<= 1)
if ((p = (b + i)) >= t) {
if ((p = t - size) > b &&
CMP(q, p) <= sense)
t = p;
else
b = p;
break;
} else if (CMP(q, p) <= sense) {
t = p;
if (i == size)
big = 0;
goto FASTCASE;
} else
b = p;
while (t > b+size) {
i = (((t - b) / size) >> 1) * size;
if (CMP(q, p = b + i) <= sense)
t = p;
else
b = p;
}
goto COPY;
FASTCASE: while (i > size)
if (CMP(q,
p = b + (i >>= 1)) <= sense)
t = p;
else
b = p;
COPY: b = t;
}
i = size;
if (q == f1) {
if (iflag) {
ICOPY_LIST(f2, tp2, b);
ICOPY_ELT(f1, tp2, i);
} else {
CCOPY_LIST(f2, tp2, b);
CCOPY_ELT(f1, tp2, i);
}
} else {
if (iflag) {
ICOPY_LIST(f1, tp2, b);
ICOPY_ELT(f2, tp2, i);
} else {
CCOPY_LIST(f1, tp2, b);
CCOPY_ELT(f2, tp2, i);
}
}
}
if (f2 < l2) {
if (iflag)
ICOPY_LIST(f2, tp2, l2);
else
CCOPY_LIST(f2, tp2, l2);
} else if (f1 < l1) {
if (iflag)
ICOPY_LIST(f1, tp2, l1);
else
CCOPY_LIST(f1, tp2, l1);
}
*p1 = l2;
}
tp2 = list1; /* swap list1, list2 */
list1 = list2;
list2 = tp2;
last = list2 + nmemb*size;
}
if (base == list2) {
memmove(list2, list1, nmemb*size);
list2 = list1;
}
free(list2);
return (0);
}
#define swap(a, b) { \
s = b; \
i = size; \
do { \
tmp = *a; *a++ = *s; *s++ = tmp; \
} while (--i); \
a -= size; \
}
#define reverse(bot, top) { \
s = top; \
do { \
i = size; \
do { \
tmp = *bot; *bot++ = *s; *s++ = tmp; \
} while (--i); \
s -= size2; \
} while(bot < s); \
}
/*
* Optional hybrid natural/pairwise first pass. Eats up list1 in runs of
* increasing order, list2 in a corresponding linked list. Checks for runs
* when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL
* is defined. Otherwise simple pairwise merging is used.)
*/
void
setup(u_char *list1, u_char *list2, size_t n, size_t size, cmp_t cmp)
{
int i, length, size2, tmp, sense;
u_char *f1, *f2, *s, *l2, *last, *p2;
size2 = size*2;
if (n <= 5) {
insertionsort(list1, n, size, cmp);
*EVAL(list2) = (u_char*) list2 + n*size;
return;
}
/*
* Avoid running pointers out of bounds; limit n to evens
* for simplicity.
*/
i = 4 + (n & 1);
insertionsort(list1 + (n - i) * size, i, size, cmp);
last = list1 + size * (n - i);
*EVAL(list2 + (last - list1)) = list2 + n * size;
#ifdef NATURAL
p2 = list2;
f1 = list1;
sense = (CMP(f1, f1 + size) > 0);
for (; f1 < last; sense = !sense) {
length = 2;
/* Find pairs with same sense. */
for (f2 = f1 + size2; f2 < last; f2 += size2) {
if ((CMP(f2, f2+ size) > 0) != sense)
break;
length += 2;
}
if (length < THRESHOLD) { /* Pairwise merge */
do {
p2 = *EVAL(p2) = f1 + size2 - list1 + list2;
if (sense > 0)
swap (f1, f1 + size);
} while ((f1 += size2) < f2);
} else { /* Natural merge */
l2 = f2;
for (f2 = f1 + size2; f2 < l2; f2 += size2) {
if ((CMP(f2-size, f2) > 0) != sense) {
p2 = *EVAL(p2) = f2 - list1 + list2;
if (sense > 0)
reverse(f1, f2-size);
f1 = f2;
}
}
if (sense > 0)
reverse (f1, f2-size);
f1 = f2;
if (f2 < last || CMP(f2 - size, f2) > 0)
p2 = *EVAL(p2) = f2 - list1 + list2;
else
p2 = *EVAL(p2) = list2 + n*size;
}
}
#else /* pairwise merge only. */
for (f1 = list1, p2 = list2; f1 < last; f1 += size2) {
p2 = *EVAL(p2) = p2 + size2;
if (CMP (f1, f1 + size) > 0)
swap(f1, f1 + size);
}
#endif /* NATURAL */
}
/*
* This is to avoid out-of-bounds addresses in sorting the
* last 4 elements.
*/
static void
insertionsort(u_char *a, size_t n, size_t size, cmp_t cmp)
{
u_char *ai, *s, *t, *u, tmp;
int i;
for (ai = a+size; --n >= 1; ai += size)
for (t = ai; t > a; t -= size) {
u = t - size;
if (CMP(u, t) <= 0)
break;
swap(u, t);
}
}