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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.

134
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;
} 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;
/* 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;
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;
}
@ -199,9 +199,9 @@ 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. */
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)
{
@ -220,7 +220,6 @@ g_qsort_with_data (gconstpointer pbase,
/* Push larger left partition indices. */
PUSH (lo, right_ptr);
lo = left_ptr;
}
else
{
@ -232,25 +231,25 @@ g_qsort_with_data (gconstpointer pbase,
}
/* 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)
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)
@ -262,9 +261,7 @@ 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;
@ -278,8 +275,7 @@ g_qsort_with_data (gconstpointer pbase,
char c = *trav;
char *hi, *lo;
for (hi = lo = trav;
(lo -= size) >= tmp_ptr; hi = lo)
for (hi = lo = trav; (lo -= size) >= tmp_ptr; hi = lo)
*hi = *lo;
*hi = c;
}