Qt 4.8
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concurrent
qtconcurrentmedian.h
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#ifndef QTCONCURRENT_MEDIAN_H
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#define QTCONCURRENT_MEDIAN_H
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#include <QtCore/qglobal.h>
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#ifndef QT_NO_CONCURRENT
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#include <QtCore/qvector.h>
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#include <QtCore/qalgorithms.h>
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QT_BEGIN_HEADER
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QT_BEGIN_NAMESPACE
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QT_MODULE
(Core)
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#ifndef qdoc
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namespace
QtConcurrent
{
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template
<
typename
T>
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class
Median
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{
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public
:
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Median(
int
_bufferSize)
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: currentMedian(), bufferSize(_bufferSize), currentIndex(0), valid(false), dirty(true)
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{
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values
.resize(bufferSize);
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}
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void
reset
()
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{
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values
.fill(0);
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currentIndex = 0;
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valid =
false
;
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dirty =
true
;
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}
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void
addValue(T value)
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{
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currentIndex = ((currentIndex + 1) % bufferSize);
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if
(valid ==
false
&& currentIndex % bufferSize == 0)
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valid =
true
;
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// Only update the cached median value when we have to, that
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// is when the new value is on then other side of the median
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// compared to the current value at the index.
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const
T currentIndexValue =
values
[currentIndex];
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if
((currentIndexValue > currentMedian && currentMedian > value)
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|| (currentMedian > currentIndexValue && value > currentMedian)) {
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dirty =
true
;
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}
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values
[currentIndex] = value;
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}
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bool
isMedianValid()
const
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{
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return
valid;
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}
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T median()
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{
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if
(dirty) {
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dirty =
false
;
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QVector<T>
sorted =
values
;
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qSort
(sorted);
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currentMedian = sorted.
at
(bufferSize / 2 + 1);
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}
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return
currentMedian;
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}
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private
:
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QVector<T>
values
;
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T currentMedian;
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int
bufferSize;
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int
currentIndex;
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bool
valid;
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bool
dirty;
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};
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}
// namespace QtConcurrent
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#endif //qdoc
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QT_END_NAMESPACE
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QT_END_HEADER
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#endif // QT_NO_CONCURRENT
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#endif
QT_END_NAMESPACE
#define QT_END_NAMESPACE
This macro expands to.
Definition:
qglobal.h:90
QT_MODULE
#define QT_MODULE(x)
Definition:
qglobal.h:2783
QT_BEGIN_HEADER
#define QT_BEGIN_HEADER
Definition:
qglobal.h:136
reset
Q_CORE_EXPORT QTextStream & reset(QTextStream &s)
QVector
The QVector class is a template class that provides a dynamic array.
Definition:
qdatastream.h:64
QT_BEGIN_NAMESPACE
#define QT_BEGIN_NAMESPACE
This macro expands to.
Definition:
qglobal.h:89
values
quint16 values[128]
Definition:
qsimplecodec.cpp:55
qSort
void qSort(RandomAccessIterator start, RandomAccessIterator end)
Definition:
qalgorithms.h:177
QVector::at
const T & at(int i) const
Returns the item at index position i in the vector.
Definition:
qvector.h:350
QtConcurrent
The QtConcurrent namespace provides high-level APIs that make it possible to write multi-threaded pro...
Definition:
qtconcurrentexception.cpp:125
QT_END_HEADER
#define QT_END_HEADER
Definition:
qglobal.h:137
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