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utilities: bsearch and qsort with additional user_data pointer argument

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This commit is contained in:
Celine Mercier
2017-01-31 16:45:47 +01:00
parent c0bcdce724
commit 651c1d7845
2 changed files with 227 additions and 0 deletions
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190
src/utils.c
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@ -116,3 +116,193 @@ void* obi_get_memory_aligned_on_16(int size, int* shift)
return (memory); return (memory);
} }
/*
* A generic implementation of binary search for the Linux kernel
*
* Copyright (C) 2008-2009 Ksplice, Inc.
* Author: Tim Abbott <tabbott@ksplice.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; version 2.
*/
void* bsearch_user_data(const void* key, const void* base, size_t num, size_t size, const void* user_data,
int (*cmp)(const void *key, const void *elt, const void* user_data))
{
size_t start = 0;
size_t end = num;
size_t mid;
int result;
while (start < end)
{
mid = start + (end - start) / 2;
result = cmp(key, base + mid * size, user_data);
if (result < 0)
end = mid;
else if (result > 0)
start = mid + 1;
else
return (void*)base + mid * size;
}
return NULL;
}
/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* 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.
*/
/*
* Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
*/
#define MIN(a,b) ((a) < (b) ? a : b)
#define swapcode(TYPE, parmi, parmj, n) { \
long i = (n) / sizeof (TYPE); \
register TYPE *pi = (TYPE *) (parmi); \
register TYPE *pj = (TYPE *) (parmj); \
do { \
register TYPE t = *pi; \
*pi++ = *pj; \
*pj++ = t; \
} while (--i > 0); \
}
#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
static __inline void
swapfunc(char *a, char *b, int n, int swaptype)
{
if (swaptype <= 1)
swapcode(long, a, b, n)
else
swapcode(char, a, b, n)
}
#define swap(a, b) \
if (swaptype == 0) { \
long t = *(long *)(a); \
*(long *)(a) = *(long *)(b); \
*(long *)(b) = t; \
} else \
swapfunc(a, b, es, swaptype)
#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
static __inline char *
med3(char *a, char *b, char *c, const void *user_data, int (*cmp)(const void *, const void *, const void *))
{
return cmp(a, b, user_data) < 0 ?
(cmp(b, c, user_data) < 0 ? b : (cmp(a, c, user_data) < 0 ? c : a ))
:(cmp(b, c, user_data) > 0 ? b : (cmp(a, c, user_data) < 0 ? a : c ));
}
void
qsort_user_data(void *aa, size_t n, size_t es, const void *user_data, int (*cmp)(const void *, const void *, const void *))
{
char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
int d, r, swaptype, swap_cnt;
register char *a = aa;
loop: SWAPINIT(a, es);
swap_cnt = 0;
if (n < 7) {
for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
for (pl = pm; pl > (char *) a && cmp(pl - es, pl, user_data) > 0;
pl -= es)
swap(pl, pl - es);
return;
}
pm = (char *)a + (n / 2) * es;
if (n > 7) {
pl = (char *)a;
pn = (char *)a + (n - 1) * es;
if (n > 40) {
d = (n / 8) * es;
pl = med3(pl, pl + d, pl + 2 * d, user_data, cmp);
pm = med3(pm - d, pm, pm + d, user_data, cmp);
pn = med3(pn - 2 * d, pn - d, pn, user_data, cmp);
}
pm = med3(pl, pm, pn, user_data, cmp);
}
swap(a, pm);
pa = pb = (char *)a + es;
pc = pd = (char *)a + (n - 1) * es;
for (;;) {
while (pb <= pc && (r = cmp(pb, a, user_data)) <= 0) {
if (r == 0) {
swap_cnt = 1;
swap(pa, pb);
pa += es;
}
pb += es;
}
while (pb <= pc && (r = cmp(pc, a, user_data)) >= 0) {
if (r == 0) {
swap_cnt = 1;
swap(pc, pd);
pd -= es;
}
pc -= es;
}
if (pb > pc)
break;
swap(pb, pc);
swap_cnt = 1;
pb += es;
pc -= es;
}
if (swap_cnt == 0) { /* Switch to insertion sort */
for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
for (pl = pm; pl > (char *) a && cmp(pl - es, pl, user_data) > 0;
pl -= es)
swap(pl, pl - es);
return;
}
pn = (char *)a + n * es;
r = MIN(pa - (char *)a, pb - pa);
vecswap(a, pb - r, r);
r = MIN((long)(pd - pc), (long)(pn - pd - es));
vecswap(pb, pn - r, r);
if ((r = pb - pa) > (int)es)
qsort_user_data(a, r / es, es, user_data, cmp);
if ((r = pd - pc) > (int)es) {
/* Iterate rather than recurse to save stack space */
a = pn - r;
n = r / es;
goto loop;
}
/* qsort(pn - r, r / es, es, cmp);*/
}

37
src/utils.h
View File

@ -74,4 +74,41 @@ char* obi_format_date(time_t date);
void* obi_get_memory_aligned_on_16(int size, int* shift); void* obi_get_memory_aligned_on_16(int size, int* shift);
/**
* @brief Version of quick sort modified to allow the user to provide an
* additional pointer sent to the comparison function.
*
* @param key This is the pointer to the object that serves as key for the search, type-casted as a void*.
* @param base This is the pointer to the first object of the array where the search is performed, type-casted as a void*.
* @param num This is the number of elements in the array pointed by base.
* @param size This is the size in bytes of each element in the array.
* @param user_data This is an additional pointer passed to the comparison function.
* @param cmp This is the function that compares two elements, eventually with an additional pointer.
*
* @returns A pointer to an entry in the array that matches the search key.
* @retval NULL if key is not found.
*
* @since January 2017
* @author original code modified by Celine Mercier (celine.mercier@metabarcoding.org)
*/
void* bsearch_user_data(const void* key, const void* base, size_t num, size_t size, const void* user_data,
int (*cmp)(const void *key, const void *elt, const void* user_data));
/**
* @brief Version of quick sort modified to allow the user to provide an
* additional pointer sent to the comparison function.
*
* @param aa This is the pointer to the first element of the array to be sorted.
* @param n This is the number of elements in the array pointed by base.
* @param es This is the size in bytes of each element in the array.
* @param user_data This is an additional pointer passed to the comparison function.
* @param cmp This is the function that compares two elements, eventually with an additional pointer.
*
* @since January 2017
* @author original code modified by Celine Mercier (celine.mercier@metabarcoding.org)
*/
void qsort_user_data(void *aa, size_t n, size_t es, const void *user_data, int (*cmp)(const void *, const void *, const void *));
#endif /* UTILS_H_ */ #endif /* UTILS_H_ */