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Sync to glibc. (#133994, Morten Welinder, patch by Kjartan Maraas)

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2005-01-13  Matthias Clasen  <mclasen@redhat.com>

	* glib/gqsort.c: Sync to glibc.  (#133994, Morten Welinder,
	patch by Kjartan Maraas)
This commit is contained in:
Matthias Clasen 2005-01-13 18:04:18 +00:00 committed by Matthias Clasen
parent 9bd80d9cb4
commit 158f95a4bd
5 changed files with 126 additions and 110 deletions
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5
ChangeLog
View File

@ -1,3 +1,8 @@
2005-01-13 Matthias Clasen <mclasen@redhat.com>
* glib/gqsort.c: Sync to glibc. (#133994, Morten Welinder,
patch by Kjartan Maraas)
2005-01-11 Owen Taylor <otaylor@redhat.com>
* configure.in: Add gmodule-export-2.0.pc to AC_CONFIG_FILES.

5
ChangeLog.pre-2-10
View File

@ -1,3 +1,8 @@
2005-01-13 Matthias Clasen <mclasen@redhat.com>
* glib/gqsort.c: Sync to glibc. (#133994, Morten Welinder,
patch by Kjartan Maraas)
2005-01-11 Owen Taylor <otaylor@redhat.com>
* configure.in: Add gmodule-export-2.0.pc to AC_CONFIG_FILES.

5
ChangeLog.pre-2-12
View File

@ -1,3 +1,8 @@
2005-01-13 Matthias Clasen <mclasen@redhat.com>
* glib/gqsort.c: Sync to glibc. (#133994, Morten Welinder,
patch by Kjartan Maraas)
2005-01-11 Owen Taylor <otaylor@redhat.com>
* configure.in: Add gmodule-export-2.0.pc to AC_CONFIG_FILES.

5
ChangeLog.pre-2-8
View File

@ -1,3 +1,8 @@
2005-01-13 Matthias Clasen <mclasen@redhat.com>
* glib/gqsort.c: Sync to glibc. (#133994, Morten Welinder,
patch by Kjartan Maraas)
2005-01-11 Owen Taylor <otaylor@redhat.com>
* configure.in: Add gmodule-export-2.0.pc to AC_CONFIG_FILES.

216
glib/gqsort.c
View File

@ -1,5 +1,5 @@
/* GLIB - Library of useful routines for C programming
* Copyright (C) 1991, 1992, 1996, 1997 Free Software Foundation, Inc.
* Copyright (C) 1991, 1992, 1996, 1997,1999,2004 Free Software Foundation, Inc.
* Copyright (C) 2000 Eazel, Inc.
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
@ -34,12 +34,14 @@
#include "config.h"
#include <alloca.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include "galias.h"
#include "glib.h"
/* Byte-wise swap two items of size SIZE. */
#define SWAP(a, b, size) \
do \
@ -60,42 +62,45 @@
/* Stack node declarations used to store unfulfilled partition obligations. */
typedef struct
{
char *lo;
char *hi;
}
stack_node;
{
char *lo;
char *hi;
} 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)
/* Order size using quicksort. This implementation incorporates
* four optimizations discussed in Sedgewick:
*
* 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.
*
* 2. Chose the pivot element using a median-of-three decision tree. This
* reduces the probability of selecting a bad pivot value and eliminates
* certain * extraneous comparisons.
*
* 3. Only quicksorts TOTAL_ELEMS / MAX_THRESH partitions, leaving insertion
* sort to order the MAX_THRESH items within each partition. This is a big
* win, since insertion sort is faster for small, mostly sorted array
* segments.
*
* 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) stack size is needed (actually O(1)
* in this case)!
*/
four optimizations discussed in Sedgewick:
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 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
eliminates certain extraneous comparisons.
3. Only quicksorts TOTAL_ELEMS / MAX_THRESH partitions, leaving
insertion sort to order the MAX_THRESH items within each partition.
This is a big win, since insertion sort is faster for small, mostly
sorted array segments.
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 (total_elems)
stack size is needed (actually O(1) in this case)! */
/**
* g_qsort_with_data:
@ -118,10 +123,6 @@ g_qsort_with_data (gconstpointer pbase,
{
register char *base_ptr = (char *) pbase;
/* Allocating SIZE bytes for a pivot buffer facilitates a better
* algorithm below since we can do comparisons directly on the pivot.
*/
char *pivot_buffer = (char *) g_alloca (size);
const size_t max_thresh = MAX_THRESH * size;
g_return_if_fail (total_elems >= 0);
@ -129,27 +130,28 @@ g_qsort_with_data (gconstpointer pbase,
g_return_if_fail (compare_func != NULL);
if (total_elems == 0)
/* Avoid lossage with unsigned arithmetic below. */
return;
if (total_elems > MAX_THRESH)
{
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;
stack_node *top = stack;
PUSH (NULL, NULL);
while (STACK_NOT_EMPTY)
{
char *left_ptr;
char *right_ptr;
char *pivot = pivot_buffer;
{
char *left_ptr;
char *right_ptr;
/* 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. */
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 in
the while loops. */
char *mid = lo + size * ((hi - lo) / size >> 1);
@ -162,30 +164,28 @@ g_qsort_with_data (gconstpointer pbase,
if ((*compare_func) ((void *) mid, (void *) lo, user_data) < 0)
SWAP (mid, lo, size);
jump_over:;
memcpy (pivot, mid, size);
pivot = pivot_buffer;
left_ptr = lo + size;
left_ptr = lo + size;
right_ptr = hi - size;
/* Here's the famous ``collapse the walls'' section of quicksort.
* Gotta like those tight inner loops! They are the main reason
* that this algorithm runs much faster than others. */
Gotta like those tight inner loops! They are the main reason
that this algorithm runs much faster than others. */
do
{
while ((*compare_func)
((void *) left_ptr, (void *) pivot,
user_data) < 0)
while ((*compare_func) ((void *) left_ptr, (void *) mid, user_data) < 0)
left_ptr += size;
while ((*compare_func)
((void *) pivot, (void *) right_ptr,
user_data) < 0)
while ((*compare_func) ((void *) mid, (void *) right_ptr, user_data) < 0)
right_ptr -= size;
if (left_ptr < right_ptr)
{
SWAP (left_ptr, right_ptr, size);
if (mid == left_ptr)
mid = right_ptr;
else if (mid == right_ptr)
mid = left_ptr;
left_ptr += size;
right_ptr -= size;
}
@ -198,60 +198,59 @@ g_qsort_with_data (gconstpointer pbase,
}
while (left_ptr <= right_ptr);
/* Set up pointers for next iteration. First determine whether
* left and right partitions are below the threshold size. If so,
* ignore one or both. Otherwise, push the larger partition's
* bounds on the stack and continue sorting the smaller one. */
/* Set up pointers for next iteration. First determine whether
left and right partitions are below the threshold size. If so,
ignore one or both. Otherwise, push the larger partition's
bounds on the stack and continue sorting the smaller one. */
if ((size_t) (right_ptr - lo) <= max_thresh)
{
if ((size_t) (hi - left_ptr) <= max_thresh)
if ((size_t) (right_ptr - lo) <= max_thresh)
{
if ((size_t) (hi - left_ptr) <= max_thresh)
/* Ignore both small partitions. */
POP (lo, hi);
else
POP (lo, hi);
else
/* Ignore small left partition. */
lo = left_ptr;
}
else if ((size_t) (hi - left_ptr) <= max_thresh)
/* Ignore small right partition. */
hi = right_ptr;
else if ((right_ptr - lo) > (hi - left_ptr))
{
/* Push larger left partition indices. */
PUSH (lo, right_ptr);
lo = left_ptr;
}
else
{
/* Push larger right partition indices. */
PUSH (left_ptr, hi);
hi = right_ptr;
}
}
lo = left_ptr;
}
else if ((size_t) (hi - left_ptr) <= max_thresh)
/* Ignore small right partition. */
hi = right_ptr;
else if ((right_ptr - lo) > (hi - left_ptr))
{
/* Push larger left partition indices. */
PUSH (lo, right_ptr);
lo = left_ptr;
}
else
{
/* Push larger right partition indices. */
PUSH (left_ptr, hi);
hi = right_ptr;
}
}
}
/* Once the BASE_PTR array is partially sorted by quicksort the rest
* is completely sorted using insertion sort, since this is efficient
* for partitions below MAX_THRESH size. BASE_PTR points to the beginning
* of the array to sort, and END_PTR points at the very last element in
* the array (*not* one beyond it!). */
is completely sorted using insertion sort, since this is efficient
for partitions below MAX_THRESH size. BASE_PTR points to the beginning
of the array to sort, and END_PTR points at the very last element in
the array (*not* one beyond it!). */
#define min(x, y) ((x) < (y) ? (x) : (y))
{
char *const end_ptr = &base_ptr[size * (total_elems - 1)];
char *tmp_ptr = base_ptr;
char *thresh = MIN (end_ptr, base_ptr + max_thresh);
char *thresh = min(end_ptr, base_ptr + max_thresh);
register char *run_ptr;
/* Find smallest element in first threshold and place it at the
* array's beginning. This is the smallest array element,
* and the operation speeds up insertion sort's inner loop. */
array's beginning. This is the smallest array element,
and the operation speeds up insertion sort's inner loop. */
for (run_ptr = tmp_ptr + size; run_ptr <= thresh;
run_ptr +=
size) if ((*compare_func) ((void *) run_ptr, (void *) tmp_ptr,
user_data) < 0)
tmp_ptr = run_ptr;
for (run_ptr = tmp_ptr + size; run_ptr <= thresh; run_ptr += size)
if ((*compare_func) ((void *) run_ptr, (void *) tmp_ptr, user_data) < 0)
tmp_ptr = run_ptr;
if (tmp_ptr != base_ptr)
SWAP (tmp_ptr, base_ptr, size);
@ -262,28 +261,25 @@ g_qsort_with_data (gconstpointer pbase,
while ((run_ptr += size) <= end_ptr)
{
tmp_ptr = run_ptr - size;
while ((*compare_func)
((void *) run_ptr, (void *) tmp_ptr,
user_data) < 0)
while ((*compare_func) ((void *) run_ptr, (void *) tmp_ptr, user_data) < 0)
tmp_ptr -= size;
tmp_ptr += size;
if (tmp_ptr != run_ptr)
{
char *trav;
if (tmp_ptr != run_ptr)
{
char *trav;
trav = run_ptr + size;
while (--trav >= run_ptr)
{
char c = *trav;
char *hi, *lo;
{
char c = *trav;
char *hi, *lo;
for (hi = lo = trav;
(lo -= size) >= tmp_ptr; hi = lo)
*hi = *lo;
*hi = c;
}
}
for (hi = lo = trav; (lo -= size) >= tmp_ptr; hi = lo)
*hi = *lo;
*hi = c;
}
}
}
}
}