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/***************************************************************************
* Copyright (C) 2008 by Benjamin Knispel, Holger Pletsch *
* benjamin.knispel[AT]aei.mpg.de *
* Copyright (C) 2009, 2010 by Oliver Bock *
* oliver.bock[AT]aei.mpg.de *
* Copyright (C) 2009, 2010 by Heinz-Bernd Eggenstein *
* *
* This file is part of Einstein@Home (Radio Pulsar Edition). *
* *
* Description: *
* harmonic summing core implementation. This is the main function *
* used for CPU variant, but is also called by the CUDA variant for *
* fixing boundary values. Derived from ABP2 code for harmonic summing *
* *
* Einstein@Home is free software: you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published *
* by the Free Software Foundation, version 2 of the License. *
* *
* Einstein@Home is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License *
* along with Einstein@Home. If not, see <http://www.gnu.org/licenses/>. *
* *
***************************************************************************/
#include "hs_common.h"
extern "C" {
int harmonic_summing(float ** const sumspec,
int32_t ** const dirty,
const float * const powerspectrum,
const unsigned int window_2,
const unsigned int fundamental_idx_hi,
const unsigned int harmonic_idx_hi,
const float * const thr) {
// loop over frequency bins and maximize the summed power at each bin for each number of summed harmonics
// Semantics of "dirty" array:
// if element at the ith index of powerspectrum of 2^k th harmonic is exceeding the threshold thr[k],
// mark the surrounding "page" of (2^LOG_PS_PAGE_SIZE) elements as "dirty" by setting
// dirty[k][i >> LOG_PS_PAGE_SIZE]
// The rationale is that only blocks of (2^LOG_PS_PAGE_SIZE) elements indicated by correctponding entries in dirty[][]
// need to be inspected in the signal toplist candidate selection phase which is following after
// the harmonic summing
// but first ... some precomputations
// compute idx16[l] = i *l + 8 , start with i = window_2
// note that floor(idx16[l] / 16 ) = floor(i* l/16 +0.5) , without any floating point math
unsigned int i,l;
unsigned int idx16[16];
float sum1=0.0f;
unsigned int j1;
float sum2=0.0f;
unsigned int j2;
float sum3=0.0f;
unsigned int j3;
float sum4=0.0f;
unsigned int j4;
for(l=0;l < 16 ; l++) {
idx16[l] = window_2 * l + 8;
}
for(i = window_2; i < harmonic_idx_hi; i++)
{
float sum;
float power;
unsigned int j;
// first harmonic
sum = powerspectrum[i];
if((sum > thr[0]) && (i < fundamental_idx_hi)) {dirty[0][i >> LOG_PS_PAGE_SIZE]=1; };
// up to second harmonic at j
j = idx16[8] >> 4;
sum += powerspectrum[j];
// if we visit a new summspec cell, reset the cached sum
if(j != j1) {sum1 = 0.0;}
if(j < fundamental_idx_hi) {
power=(sum > sum1) ? sum : sum1;
if (power > thr[1]) {
sumspec[1][j]=power;
dirty[1][j >> LOG_PS_PAGE_SIZE]=1;
}else {
// make sure the sumspec value is initialized even if no threshold
// is passed
if(j != j1) {sumspec[1][j]=power;}
}
}
j1=j;
sum1=power;
// up to fourth harmonic at j
j = idx16[4] >> 4;
sum += powerspectrum[idx16[12]>>4] + powerspectrum[j];
if(j != j2) {sum2 = 0.0;}
if(j < fundamental_idx_hi) {
power=(sum > sum2) ? sum : sum2;
if (power > thr[2]) {
sumspec[2][j]=power;
dirty[2][j >> LOG_PS_PAGE_SIZE]=1;
} else {
// make sure the sumspec value is initialized even if no threshold
// is passed
if(j != j2) {sumspec[2][j]=power;}
}
}
j2=j;
sum2=power;
// up to eighth harmonic at j
j = idx16[2] >>4;
sum += powerspectrum[idx16[14] >>4] + powerspectrum[idx16[10] >>4] + \
powerspectrum[idx16[6] >>4] + powerspectrum[j];
if(j != j3) {sum3 = 0.0;}
if(j < fundamental_idx_hi) {
power=(sum > sum3) ? sum : sum3;
if (power > thr[3]) {
sumspec[3][j]=power;
dirty[3][j >> LOG_PS_PAGE_SIZE]=1;
} else {
// make sure the sumspec value is initialized even if no threshold
// is passed
if(j != j3) {sumspec[3][j]=power;}
}
}
j3=j;
sum3=power;
// up to sixteenth harmonic at j
j = idx16[1] >>4;
sum += powerspectrum[idx16[15] >>4] + powerspectrum[idx16[13] >>4] + \
powerspectrum[idx16[11] >>4] + powerspectrum[idx16[9] >>4] + \
powerspectrum[idx16[7] >>4] + powerspectrum[idx16[5] >>4] + \
powerspectrum[idx16[3] >>4] + powerspectrum[j];
if(j != j4) {sum4 = 0.0;}
if(j < fundamental_idx_hi) {
power=(sum > sum4) ? sum : sum4;
if (power > thr[4]) {
sumspec[4][j]=power;
dirty[4][j >> LOG_PS_PAGE_SIZE]=1;
}else {
// make sure the sumspec value is initialized even if no threshold
// is passed
if(j != j4) {sumspec[4][j]=power;}
}
}
j4=j;
sum4=power; // update the indices
for(l=0;l < 16 ; l++) {
idx16[l]+=l;
}
}// end of loop over frequency bins
return 0;
}
} /* extern "C" */
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