Update.
1999-10-26 Andreas Jaeger <aj@suse.de> * stdlib/msort.c: Include <alloca.h> for prototype. Remove K&R compatibility and _quicksort prototype. * stdlib/qsort.c: Make code and comments 64 bit clean; clarify some comments. Reported by Bernd Löchner <loechner@informatik.uni-kl.de>. Remove K&R compatibility. Move prototype declaration to include/stdlib.h. Include <alloca.h> for prototype; include <limits.h> for CHAR_BIT. * include/stdlib.h: Prototype declaration for _quicksort.
This commit is contained in:
Ulrich Drepper
parent
253d0b2377
commit
061d137bd7
14
ChangeLog
14
ChangeLog
|
|
@ -1,3 +1,17 @@
|
|||
1999-10-26 Andreas Jaeger <aj@suse.de>
|
||||
|
||||
* stdlib/msort.c: Include <alloca.h> for prototype.
|
||||
Remove K&R compatibility and _quicksort prototype.
|
||||
|
||||
* stdlib/qsort.c: Make code and comments 64 bit clean; clarify
|
||||
some comments.
|
||||
Reported by Bernd Löchner <loechner@informatik.uni-kl.de>.
|
||||
Remove K&R compatibility.
|
||||
Move prototype declaration to include/stdlib.h.
|
||||
Include <alloca.h> for prototype; include <limits.h> for CHAR_BIT.
|
||||
|
||||
* include/stdlib.h: Prototype declaration for _quicksort.
|
||||
|
||||
1999-10-27 Andreas Jaeger <aj@suse.de>
|
||||
|
||||
* stdlib/rand_r.c (rand_r): Really use 31 bits, the result was
|
||||
|
|
|
|||
|
|
@ -49,6 +49,10 @@ extern int __getpt (void) __THROW;
|
|||
|
||||
extern int __add_to_environ (const char *name, const char *value,
|
||||
const char *combines, int replace);
|
||||
|
||||
extern void _quicksort (void *const pbase, size_t total_elems,
|
||||
size_t size, __compar_fn_t cmp);
|
||||
|
||||
#endif
|
||||
#undef __Need_M_And_C
|
||||
|
||||
|
|
|
|||
|
|
@ -1,6 +1,6 @@
|
|||
/* An alternative to qsort, with an identical interface.
|
||||
This file is part of the GNU C Library.
|
||||
Copyright (C) 1992, 1995, 1996, 1997 Free Software Foundation, Inc.
|
||||
Copyright (C) 1992, 1995, 1996, 1997, 1999 Free Software Foundation, Inc.
|
||||
Written by Mike Haertel, September 1988.
|
||||
|
||||
The GNU C Library is free software; you can redistribute it and/or
|
||||
|
|
@ -18,21 +18,18 @@
|
|||
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
||||
Boston, MA 02111-1307, USA. */
|
||||
|
||||
#include <alloca.h>
|
||||
#include <stdlib.h>
|
||||
#include <string.h>
|
||||
#include <memcopy.h>
|
||||
#include <errno.h>
|
||||
|
||||
static void msort_with_tmp __P ((void *b, size_t n, size_t s,
|
||||
__compar_fn_t cmp, char *t));
|
||||
static void msort_with_tmp (void *b, size_t n, size_t s,
|
||||
__compar_fn_t cmp, char *t);
|
||||
|
||||
static void
|
||||
msort_with_tmp (b, n, s, cmp, t)
|
||||
void *b;
|
||||
size_t n;
|
||||
size_t s;
|
||||
__compar_fn_t cmp;
|
||||
char *t;
|
||||
msort_with_tmp (void *b, size_t n, size_t s, __compar_fn_t cmp,
|
||||
char *t)
|
||||
{
|
||||
char *tmp;
|
||||
char *b1, *b2;
|
||||
|
|
@ -88,11 +85,7 @@ msort_with_tmp (b, n, s, cmp, t)
|
|||
}
|
||||
|
||||
void
|
||||
qsort (b, n, s, cmp)
|
||||
void *b;
|
||||
size_t n;
|
||||
size_t s;
|
||||
__compar_fn_t cmp;
|
||||
qsort (void *b, size_t n, size_t s, __compar_fn_t cmp)
|
||||
{
|
||||
const size_t size = n * s;
|
||||
|
||||
|
|
@ -108,9 +101,6 @@ qsort (b, n, s, cmp)
|
|||
{
|
||||
/* Couldn't get space, so use the slower algorithm
|
||||
that doesn't need a temporary array. */
|
||||
extern void _quicksort __P ((void *const __base,
|
||||
size_t __nmemb, size_t __size,
|
||||
__compar_fn_t __compar));
|
||||
_quicksort (b, n, s, cmp);
|
||||
}
|
||||
else
|
||||
|
|
|
|||
|
|
@ -1,4 +1,4 @@
|
|||
/* Copyright (C) 1991, 1992, 1996, 1997 Free Software Foundation, Inc.
|
||||
/* Copyright (C) 1991, 1992, 1996, 1997, 1999 Free Software Foundation, Inc.
|
||||
This file is part of the GNU C Library.
|
||||
Written by Douglas C. Schmidt (schmidt@ics.uci.edu).
|
||||
|
||||
|
|
@ -17,12 +17,15 @@
|
|||
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
||||
Boston, MA 02111-1307, USA. */
|
||||
|
||||
/* If you consider tuning this algorithm, you should consult first:
|
||||
Engineering a sort function; Jon Bentley and M. Douglas McIlroy;
|
||||
Software - Practice and Experience; Vol. 23 (11), 1249-1265, 1993. */
|
||||
|
||||
#include <alloca.h>
|
||||
#include <limits.h>
|
||||
#include <stdlib.h>
|
||||
#include <string.h>
|
||||
|
||||
extern void _quicksort __P ((void *const pbase, size_t total_elems,
|
||||
size_t size, __compar_fn_t cmp));
|
||||
|
||||
/* Byte-wise swap two items of size SIZE. */
|
||||
#define SWAP(a, b, size) \
|
||||
do \
|
||||
|
|
@ -49,7 +52,11 @@ typedef struct
|
|||
} stack_node;
|
||||
|
||||
/* The next 4 #defines implement a very fast in-line stack abstraction. */
|
||||
#define STACK_SIZE (8 * sizeof(unsigned long int))
|
||||
/* The stack needs log (total_elements) entries (we could even subtract
|
||||
log(MAX_THRESH)). Since total_elements has type size_t, we get as
|
||||
upper bound for log (total_elements):
|
||||
bits per byte (CHAR_BIT) * sizeof(size_t). */
|
||||
#define STACK_SIZE (CHAR_BIT * sizeof(size_t))
|
||||
#define PUSH(low, high) ((void) ((top->lo = (low)), (top->hi = (high)), ++top))
|
||||
#define POP(low, high) ((void) (--top, (low = top->lo), (high = top->hi)))
|
||||
#define STACK_NOT_EMPTY (stack < top)
|
||||
|
|
@ -60,9 +67,10 @@ typedef struct
|
|||
|
||||
1. Non-recursive, using an explicit stack of pointer that store the
|
||||
next array partition to sort. To save time, this maximum amount
|
||||
of space required to store an array of MAX_INT is allocated on the
|
||||
stack. Assuming a 32-bit integer, this needs only 32 *
|
||||
sizeof(stack_node) == 136 bits. Pretty cheap, actually.
|
||||
of space required to store an array of SIZE_MAX is allocated on the
|
||||
stack. Assuming a 32-bit (64 bit) integer for size_t, this needs
|
||||
only 32 * sizeof(stack_node) == 256 bytes (for 64 bit: 1024 bytes).
|
||||
Pretty cheap, actually.
|
||||
|
||||
2. Chose the pivot element using a median-of-three decision tree.
|
||||
This reduces the probability of selecting a bad pivot value and
|
||||
|
|
@ -75,15 +83,12 @@ typedef struct
|
|||
|
||||
4. The larger of the two sub-partitions is always pushed onto the
|
||||
stack first, with the algorithm then concentrating on the
|
||||
smaller partition. This *guarantees* no more than log (n)
|
||||
smaller partition. This *guarantees* no more than log (total_elems)
|
||||
stack size is needed (actually O(1) in this case)! */
|
||||
|
||||
void
|
||||
_quicksort (pbase, total_elems, size, cmp)
|
||||
void *const pbase;
|
||||
size_t total_elems;
|
||||
size_t size;
|
||||
__compar_fn_t cmp;
|
||||
_quicksort (void *const pbase, size_t total_elems, size_t size,
|
||||
__compar_fn_t cmp)
|
||||
{
|
||||
register char *base_ptr = (char *) pbase;
|
||||
|
||||
|
|
@ -100,7 +105,6 @@ _quicksort (pbase, total_elems, size, cmp)
|
|||
{
|
||||
char *lo = base_ptr;
|
||||
char *hi = &lo[size * (total_elems - 1)];
|
||||
/* Largest size needed for 32-bit int!!! */
|
||||
stack_node stack[STACK_SIZE];
|
||||
stack_node *top = stack + 1;
|
||||
|
||||
|
|
@ -114,7 +118,8 @@ _quicksort (pbase, total_elems, size, cmp)
|
|||
/* Select median value from among LO, MID, and HI. Rearrange
|
||||
LO and HI so the three values are sorted. This lowers the
|
||||
probability of picking a pathological pivot value and
|
||||
skips a comparison for both the LEFT_PTR and RIGHT_PTR. */
|
||||
skips a comparison for both the LEFT_PTR and RIGHT_PTR in
|
||||
the while loops. */
|
||||
|
||||
char *mid = lo + size * ((hi - lo) / size >> 1);
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue