62 lines
1.5 KiB
C++
62 lines
1.5 KiB
C++
// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; tab-width: 8 -*-
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// this version expands convolve8_cpp by making Vec mimic the structure of
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// NumericVector. It peforms well, so this is is not the structure of
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// NumericVector that is the problem. So what is it then ?
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//
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// could it be because NumericVector is in a different library than
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// this code, so that operator[] is not inlined ?
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//
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// clues:
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// - http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.faqs/ka3538.html
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#include <Rcpp.h>
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class Cache{
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public:
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typedef double& proxy ;
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typedef double* iterator ;
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Cache( iterator data_) : data(data_){}
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inline proxy ref(int i){ return data[i] ; }
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inline proxy ref(int i) const { return data[i] ; }
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private:
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iterator data ;
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} ;
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class Vec {
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public:
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typedef double& proxy ;
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Vec( double* data_ ) : cache(data_){}
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inline proxy operator[]( int i){ return cache.ref(i) ; }
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inline proxy operator[]( int i) const { return cache.ref(i) ; }
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private:
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Cache cache ;
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} ;
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RcppExport SEXP convolve9cpp(SEXP a, SEXP b){
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Rcpp::NumericVector xa(a);
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Rcpp::NumericVector xb(b);
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int n_xa = xa.size() ;
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int n_xb = xb.size() ;
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int nab = n_xa + n_xb - 1;
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Rcpp::NumericVector xab(nab);
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Vec vab(xab.begin()), va(xa.begin()), vb(xb.begin()) ;
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for (int i = 0; i < n_xa; i++)
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for (int j = 0; j < n_xb; j++)
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vab[i + j] += va[i] * vb[j];
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return xab ;
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}
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#include "loopmacro.h"
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LOOPMACRO_CPP(convolve9cpp)
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