79 lines
1.8 KiB
C++
79 lines
1.8 KiB
C++
/*****************************************************************************
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* Qwt Examples - Copyright (C) 2002 Uwe Rathmann
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* This file may be used under the terms of the 3-clause BSD License
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*****************************************************************************/
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#include "CircularBuffer.h"
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#include <QwtMath>
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CircularBuffer::CircularBuffer( double interval, size_t numPoints )
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: m_y( NULL )
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, m_referenceTime( 0.0 )
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, m_startIndex( 0 )
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, m_offset( 0.0 )
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{
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fill( interval, numPoints );
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}
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void CircularBuffer::fill( double interval, size_t numPoints )
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{
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if ( interval <= 0.0 || numPoints < 2 )
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return;
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m_values.resize( numPoints );
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m_values.fill( 0.0 );
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if ( m_y )
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{
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m_step = interval / ( numPoints - 2 );
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for ( size_t i = 0; i < numPoints; i++ )
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m_values[i] = m_y( i * m_step );
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}
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m_interval = interval;
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}
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void CircularBuffer::setFunction( double ( * y )( double ) )
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{
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m_y = y;
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}
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void CircularBuffer::setReferenceTime( double timeStamp )
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{
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m_referenceTime = timeStamp;
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const double startTime = std::fmod( m_referenceTime, m_values.size() * m_step );
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m_startIndex = int( startTime / m_step ); // floor
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m_offset = std::fmod( startTime, m_step );
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}
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double CircularBuffer::referenceTime() const
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{
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return m_referenceTime;
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}
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size_t CircularBuffer::size() const
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{
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return m_values.size();
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}
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QPointF CircularBuffer::sample( size_t i ) const
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{
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const int size = m_values.size();
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int index = m_startIndex + i;
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if ( index >= size )
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index -= size;
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const double x = i * m_step - m_offset - m_interval;
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const double y = m_values.data()[index];
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return QPointF( x, y );
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}
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QRectF CircularBuffer::boundingRect() const
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{
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return QRectF( -1.0, -m_interval, 2.0, m_interval );
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}
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