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402 lines
11 KiB
C
402 lines
11 KiB
C
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//$ nobt
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//$ nocpp
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/**
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* @file CDSPHBDownsampler.h
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*
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* @brief Half-band downsampling convolver class.
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*
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* This file includes half-band downsampling convolver class.
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*
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* r8brain-free-src Copyright (c) 2013-2022 Aleksey Vaneev
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* See the "LICENSE" file for license.
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*/
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#ifndef R8B_CDSPHBDOWNSAMPLER_INCLUDED
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#define R8B_CDSPHBDOWNSAMPLER_INCLUDED
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#include "CDSPHBUpsampler.h"
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namespace r8b {
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/**
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* @brief Half-band downsampler class.
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*
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* Class implements brute-force half-band 2X downsampling that uses small
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* sparse symmetric FIR filters. The output has 2.0 gain.
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*/
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class CDSPHBDownsampler : public CDSPProcessor
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{
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public:
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/**
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* Constructor initalizes the half-band downsampler.
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*
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* @param ReqAtten Required half-band filter attentuation.
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* @param SteepIndex Steepness index - 0=steepest. Corresponds to general
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* downsampling ratio, e.g. at 4x downsampling 0 is used, at 8x
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* downsampling 1 is used, etc.
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* @param IsThird "True" if 1/3 resampling is performed.
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* @param PrevLatency Latency, in samples (any value >=0), which was left
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* in the output signal by a previous process. Whole-number latency will
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* be consumed by *this object while remaining fractional latency can be
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* obtained via the getLatencyFrac() function.
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*/
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CDSPHBDownsampler( const double ReqAtten, const int SteepIndex,
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const bool IsThird, const double PrevLatency )
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{
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static const CConvolveFn FltConvFn[ 14 ] = {
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&CDSPHBDownsampler :: convolve1, &CDSPHBDownsampler :: convolve2,
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&CDSPHBDownsampler :: convolve3, &CDSPHBDownsampler :: convolve4,
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&CDSPHBDownsampler :: convolve5, &CDSPHBDownsampler :: convolve6,
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&CDSPHBDownsampler :: convolve7, &CDSPHBDownsampler :: convolve8,
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&CDSPHBDownsampler :: convolve9, &CDSPHBDownsampler :: convolve10,
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&CDSPHBDownsampler :: convolve11, &CDSPHBDownsampler :: convolve12,
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&CDSPHBDownsampler :: convolve13,
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&CDSPHBDownsampler :: convolve14 };
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int fltt;
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double att;
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if( IsThird )
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{
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CDSPHBUpsampler :: getHBFilterThird( ReqAtten, SteepIndex, fltp,
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fltt, att );
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}
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else
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{
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CDSPHBUpsampler :: getHBFilter( ReqAtten, SteepIndex, fltp, fltt,
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att );
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}
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convfn = FltConvFn[ fltt - 1 ];
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fll = fltt * 2 - 1;
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fl2 = fll;
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flo = fll + fl2;
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flb = BufLen - fll;
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BufRP = Buf + fll;
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LatencyFrac = PrevLatency * 0.5;
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Latency = (int) LatencyFrac;
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LatencyFrac -= Latency;
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R8BASSERT( Latency >= 0 );
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R8BCONSOLE( "CDSPHBDownsampler: taps=%i third=%i att=%.1f io=1/2\n",
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fltt, (int) IsThird, att );
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clear();
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}
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virtual int getLatency() const
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{
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return( 0 );
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}
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virtual double getLatencyFrac() const
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{
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return( LatencyFrac );
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}
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virtual int getMaxOutLen( const int MaxInLen ) const
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{
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R8BASSERT( MaxInLen >= 0 );
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return(( MaxInLen + 1 ) >> 1 );
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}
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virtual void clear()
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{
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LatencyLeft = Latency;
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BufLeft = 0;
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WritePos = 0;
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ReadPos = flb; // Set "read" position to account for filter's latency.
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memset( &Buf[ ReadPos ], 0, ( BufLen - flb ) * sizeof( Buf[ 0 ]));
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}
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virtual int process( double* ip, int l, double*& op0 )
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{
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R8BASSERT( l >= 0 );
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double* op = op0;
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while( l > 0 )
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{
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// Add new input samples to both halves of the ring buffer.
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const int b = min( min( l, BufLen - WritePos ), flb - BufLeft );
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double* const wp1 = Buf + WritePos;
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memcpy( wp1, ip, b * sizeof( wp1[ 0 ]));
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if( WritePos < flo )
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{
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const int c = min( b, flo - WritePos );
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memcpy( wp1 + BufLen, wp1, c * sizeof( wp1[ 0 ]));
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}
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ip += b;
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WritePos = ( WritePos + b ) & BufLenMask;
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l -= b;
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BufLeft += b;
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// Produce output.
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if( BufLeft > fl2 )
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{
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const int c = ( BufLeft - fl2 + 1 ) >> 1;
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double* const opend = op + c;
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( *convfn )( op, opend, fltp, BufRP, ReadPos );
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op = opend;
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const int c2 = c + c;
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ReadPos = ( ReadPos + c2 ) & BufLenMask;
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BufLeft -= c2;
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}
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}
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int ol = (int) ( op - op0 );
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if( LatencyLeft != 0 )
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{
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if( LatencyLeft >= ol )
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{
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LatencyLeft -= ol;
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return( 0 );
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}
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ol -= LatencyLeft;
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op0 += LatencyLeft;
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LatencyLeft = 0;
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}
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return( ol );
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}
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private:
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static const int BufLenBits = 10; ///< The length of the ring buffer,
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///< expressed as Nth power of 2. This value can be reduced if it is
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///< known that only short input buffers will be passed to the
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///< interpolator. The minimum value of this parameter is 5, and
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///< 1 << BufLenBits should be at least 3 times larger than the
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///< FilterLen.
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///<
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static const int BufLen = 1 << BufLenBits; ///< The length of the ring
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///< buffer. The actual length is twice as long to allow "beyond max
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///< position" positioning.
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///<
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static const int BufLenMask = BufLen - 1; ///< Mask used for quick buffer
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///< position wrapping.
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///<
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double Buf[ BufLen + 54 ]; ///< The ring buffer, including overrun
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///< protection for the largest filter.
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///<
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const double* fltp; ///< Half-band filter taps.
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///<
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int fll; ///< Input latency.
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///<
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int fl2; ///< Right-side filter length.
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///<
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int flo; ///< Overrun length.
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///<
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int flb; ///< Initial read position and maximal buffer write length.
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///<
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const double* BufRP; ///< Offseted Buf pointer at ReadPos=0.
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///<
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int Latency; ///< Initial latency that should be removed from the output.
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///<
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double LatencyFrac; ///< Fractional latency left on the output.
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///<
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int BufLeft; ///< The number of samples left in the buffer to process.
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///< When this value is below FilterLenD2Plus1, the interpolation
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///< cycle ends.
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///<
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int WritePos; ///< The current buffer write position. Incremented together
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///< with the BufLeft variable.
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///<
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int ReadPos; ///< The current buffer read position.
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///<
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int LatencyLeft; ///< Latency left to remove.
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///<
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typedef void( *CConvolveFn )( double* op, double* const opend,
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const double* const flt, const double* const rp0, int rpos ); ///<
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///< Convolution function type.
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///<
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CConvolveFn convfn; ///< Convolution function in use.
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///<
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#define R8BHBC1( fn ) \
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static void fn( double* op, double* const opend, const double* const flt, \
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const double* const rp0, int rpos ) \
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{ \
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while( op != opend ) \
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{ \
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const double* const rp = rp0 + rpos; \
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*op = rp[ 0 ] +
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#define R8BHBC2 \
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rpos = ( rpos + 2 ) & BufLenMask; \
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op++; \
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} \
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}
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R8BHBC1( convolve1 )
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flt[ 0 ] * ( rp[ 1 ] + rp[ -1 ]);
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R8BHBC2
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R8BHBC1( convolve2 )
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flt[ 0 ] * ( rp[ 1 ] + rp[ -1 ]) +
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flt[ 1 ] * ( rp[ 3 ] + rp[ -3 ]);
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R8BHBC2
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R8BHBC1( convolve3 )
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flt[ 0 ] * ( rp[ 1 ] + rp[ -1 ]) +
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flt[ 1 ] * ( rp[ 3 ] + rp[ -3 ]) +
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flt[ 2 ] * ( rp[ 5 ] + rp[ -5 ]);
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R8BHBC2
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R8BHBC1( convolve4 )
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flt[ 0 ] * ( rp[ 1 ] + rp[ -1 ]) +
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flt[ 1 ] * ( rp[ 3 ] + rp[ -3 ]) +
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flt[ 2 ] * ( rp[ 5 ] + rp[ -5 ]) +
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flt[ 3 ] * ( rp[ 7 ] + rp[ -7 ]);
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R8BHBC2
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R8BHBC1( convolve5 )
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flt[ 0 ] * ( rp[ 1 ] + rp[ -1 ]) +
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flt[ 1 ] * ( rp[ 3 ] + rp[ -3 ]) +
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flt[ 2 ] * ( rp[ 5 ] + rp[ -5 ]) +
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flt[ 3 ] * ( rp[ 7 ] + rp[ -7 ]) +
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flt[ 4 ] * ( rp[ 9 ] + rp[ -9 ]);
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R8BHBC2
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R8BHBC1( convolve6 )
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flt[ 0 ] * ( rp[ 1 ] + rp[ -1 ]) +
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flt[ 1 ] * ( rp[ 3 ] + rp[ -3 ]) +
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flt[ 2 ] * ( rp[ 5 ] + rp[ -5 ]) +
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flt[ 3 ] * ( rp[ 7 ] + rp[ -7 ]) +
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flt[ 4 ] * ( rp[ 9 ] + rp[ -9 ]) +
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flt[ 5 ] * ( rp[ 11 ] + rp[ -11 ]);
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R8BHBC2
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R8BHBC1( convolve7 )
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flt[ 0 ] * ( rp[ 1 ] + rp[ -1 ]) +
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flt[ 1 ] * ( rp[ 3 ] + rp[ -3 ]) +
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flt[ 2 ] * ( rp[ 5 ] + rp[ -5 ]) +
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flt[ 3 ] * ( rp[ 7 ] + rp[ -7 ]) +
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flt[ 4 ] * ( rp[ 9 ] + rp[ -9 ]) +
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flt[ 5 ] * ( rp[ 11 ] + rp[ -11 ]) +
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flt[ 6 ] * ( rp[ 13 ] + rp[ -13 ]);
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R8BHBC2
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R8BHBC1( convolve8 )
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flt[ 0 ] * ( rp[ 1 ] + rp[ -1 ]) +
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flt[ 1 ] * ( rp[ 3 ] + rp[ -3 ]) +
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flt[ 2 ] * ( rp[ 5 ] + rp[ -5 ]) +
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flt[ 3 ] * ( rp[ 7 ] + rp[ -7 ]) +
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flt[ 4 ] * ( rp[ 9 ] + rp[ -9 ]) +
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flt[ 5 ] * ( rp[ 11 ] + rp[ -11 ]) +
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flt[ 6 ] * ( rp[ 13 ] + rp[ -13 ]) +
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flt[ 7 ] * ( rp[ 15 ] + rp[ -15 ]);
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R8BHBC2
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R8BHBC1( convolve9 )
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flt[ 0 ] * ( rp[ 1 ] + rp[ -1 ]) +
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flt[ 1 ] * ( rp[ 3 ] + rp[ -3 ]) +
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flt[ 2 ] * ( rp[ 5 ] + rp[ -5 ]) +
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flt[ 3 ] * ( rp[ 7 ] + rp[ -7 ]) +
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flt[ 4 ] * ( rp[ 9 ] + rp[ -9 ]) +
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flt[ 5 ] * ( rp[ 11 ] + rp[ -11 ]) +
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flt[ 6 ] * ( rp[ 13 ] + rp[ -13 ]) +
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flt[ 7 ] * ( rp[ 15 ] + rp[ -15 ]) +
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flt[ 8 ] * ( rp[ 17 ] + rp[ -17 ]);
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R8BHBC2
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R8BHBC1( convolve10 )
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flt[ 0 ] * ( rp[ 1 ] + rp[ -1 ]) +
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flt[ 1 ] * ( rp[ 3 ] + rp[ -3 ]) +
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flt[ 2 ] * ( rp[ 5 ] + rp[ -5 ]) +
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flt[ 3 ] * ( rp[ 7 ] + rp[ -7 ]) +
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flt[ 4 ] * ( rp[ 9 ] + rp[ -9 ]) +
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flt[ 5 ] * ( rp[ 11 ] + rp[ -11 ]) +
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flt[ 6 ] * ( rp[ 13 ] + rp[ -13 ]) +
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flt[ 7 ] * ( rp[ 15 ] + rp[ -15 ]) +
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flt[ 8 ] * ( rp[ 17 ] + rp[ -17 ]) +
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flt[ 9 ] * ( rp[ 19 ] + rp[ -19 ]);
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R8BHBC2
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R8BHBC1( convolve11 )
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flt[ 0 ] * ( rp[ 1 ] + rp[ -1 ]) +
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flt[ 1 ] * ( rp[ 3 ] + rp[ -3 ]) +
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flt[ 2 ] * ( rp[ 5 ] + rp[ -5 ]) +
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flt[ 3 ] * ( rp[ 7 ] + rp[ -7 ]) +
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flt[ 4 ] * ( rp[ 9 ] + rp[ -9 ]) +
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flt[ 5 ] * ( rp[ 11 ] + rp[ -11 ]) +
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flt[ 6 ] * ( rp[ 13 ] + rp[ -13 ]) +
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flt[ 7 ] * ( rp[ 15 ] + rp[ -15 ]) +
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flt[ 8 ] * ( rp[ 17 ] + rp[ -17 ]) +
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flt[ 9 ] * ( rp[ 19 ] + rp[ -19 ]) +
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flt[ 10 ] * ( rp[ 21 ] + rp[ -21 ]);
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R8BHBC2
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R8BHBC1( convolve12 )
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flt[ 0 ] * ( rp[ 1 ] + rp[ -1 ]) +
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flt[ 1 ] * ( rp[ 3 ] + rp[ -3 ]) +
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flt[ 2 ] * ( rp[ 5 ] + rp[ -5 ]) +
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flt[ 3 ] * ( rp[ 7 ] + rp[ -7 ]) +
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flt[ 4 ] * ( rp[ 9 ] + rp[ -9 ]) +
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flt[ 5 ] * ( rp[ 11 ] + rp[ -11 ]) +
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flt[ 6 ] * ( rp[ 13 ] + rp[ -13 ]) +
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flt[ 7 ] * ( rp[ 15 ] + rp[ -15 ]) +
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flt[ 8 ] * ( rp[ 17 ] + rp[ -17 ]) +
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flt[ 9 ] * ( rp[ 19 ] + rp[ -19 ]) +
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flt[ 10 ] * ( rp[ 21 ] + rp[ -21 ]) +
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flt[ 11 ] * ( rp[ 23 ] + rp[ -23 ]);
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R8BHBC2
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R8BHBC1( convolve13 )
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flt[ 0 ] * ( rp[ 1 ] + rp[ -1 ]) +
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flt[ 1 ] * ( rp[ 3 ] + rp[ -3 ]) +
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||
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flt[ 2 ] * ( rp[ 5 ] + rp[ -5 ]) +
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||
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flt[ 3 ] * ( rp[ 7 ] + rp[ -7 ]) +
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||
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flt[ 4 ] * ( rp[ 9 ] + rp[ -9 ]) +
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||
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flt[ 5 ] * ( rp[ 11 ] + rp[ -11 ]) +
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flt[ 6 ] * ( rp[ 13 ] + rp[ -13 ]) +
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||
|
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flt[ 7 ] * ( rp[ 15 ] + rp[ -15 ]) +
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||
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flt[ 8 ] * ( rp[ 17 ] + rp[ -17 ]) +
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||
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flt[ 9 ] * ( rp[ 19 ] + rp[ -19 ]) +
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||
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|
flt[ 10 ] * ( rp[ 21 ] + rp[ -21 ]) +
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||
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flt[ 11 ] * ( rp[ 23 ] + rp[ -23 ]) +
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||
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flt[ 12 ] * ( rp[ 25 ] + rp[ -25 ]);
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||
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R8BHBC2
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||
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|
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||
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|
R8BHBC1( convolve14 )
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||
|
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flt[ 0 ] * ( rp[ 1 ] + rp[ -1 ]) +
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||
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flt[ 1 ] * ( rp[ 3 ] + rp[ -3 ]) +
|
||
|
|
flt[ 2 ] * ( rp[ 5 ] + rp[ -5 ]) +
|
||
|
|
flt[ 3 ] * ( rp[ 7 ] + rp[ -7 ]) +
|
||
|
|
flt[ 4 ] * ( rp[ 9 ] + rp[ -9 ]) +
|
||
|
|
flt[ 5 ] * ( rp[ 11 ] + rp[ -11 ]) +
|
||
|
|
flt[ 6 ] * ( rp[ 13 ] + rp[ -13 ]) +
|
||
|
|
flt[ 7 ] * ( rp[ 15 ] + rp[ -15 ]) +
|
||
|
|
flt[ 8 ] * ( rp[ 17 ] + rp[ -17 ]) +
|
||
|
|
flt[ 9 ] * ( rp[ 19 ] + rp[ -19 ]) +
|
||
|
|
flt[ 10 ] * ( rp[ 21 ] + rp[ -21 ]) +
|
||
|
|
flt[ 11 ] * ( rp[ 23 ] + rp[ -23 ]) +
|
||
|
|
flt[ 12 ] * ( rp[ 25 ] + rp[ -25 ]) +
|
||
|
|
flt[ 13 ] * ( rp[ 27 ] + rp[ -27 ]);
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||
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R8BHBC2
|
||
|
|
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||
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|
#undef R8BHBC1
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||
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|
#undef R8BHBC2
|
||
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|
};
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||
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||
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// ---------------------------------------------------------------------------
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} // namespace r8b
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#endif // R8B_CDSPHBDOWNSAMPLER_INCLUDED
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