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forced_unroll.c
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forced_unroll.c
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#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "constants.h"
/**
* Deinterleave (transpose) an IQUV ring buffer page to the ordering needed for FITS files
* Note that this is probably a slow function, and is not meant to be run real-time
*
* data in: tab, channel/4, time/500 packets of time,channel,pn
* data out: tab, channel, pol, time
*
* Suggested use is:
* 1. realtime: ringbuffer -> [trigger] -> dada_dbdisk
* 2. offline: dada_dbdisk -> ringbuffer -> dadafits
*
* @param {const char *} page Ringbuffer page with interleaved data
* @param {const char *} transposed
* @param {int} ntabs Number of tabs
* @param {int} nchannels Number of channels
* @param {int} npackets Number of packets per sequence
*/
void deinterleave (const unsigned char *page, unsigned char *transposed, const int ntabs, const int nchannels, const int npackets) {
const unsigned char *packet = page;
int tab = 0;
for (tab = 0; tab < ntabs; tab++) {
int channel_offset = 0;
for (channel_offset = 0; channel_offset < nchannels; channel_offset+=4) {
unsigned char *intermediate = &transposed[(tab * nchannels + channel_offset)*NPOLS*npackets*NSAMPS];
int sequence_number = 0;
for (sequence_number = 0; sequence_number < npackets; sequence_number++) {
// process packet:
int tn;
#pragma omp parallel for
for (tn = 0; tn < NSAMPS; tn++) { // 500 samples per packet
intermediate[( 0 * NPOLS + 0) * npackets * NSAMPS + tn] = *packet++;
intermediate[( 0 * NPOLS + 1) * npackets * NSAMPS + tn] = *packet++;
intermediate[( 0 * NPOLS + 2) * npackets * NSAMPS + tn] = *packet++;
intermediate[( 0 * NPOLS + 3) * npackets * NSAMPS + tn] = *packet++;
intermediate[( 1 * NPOLS + 0) * npackets * NSAMPS + tn] = *packet++;
intermediate[( 1 * NPOLS + 1) * npackets * NSAMPS + tn] = *packet++;
intermediate[( 1 * NPOLS + 2) * npackets * NSAMPS + tn] = *packet++;
intermediate[( 1 * NPOLS + 3) * npackets * NSAMPS + tn] = *packet++;
intermediate[( 2 * NPOLS + 0) * npackets * NSAMPS + tn] = *packet++;
intermediate[( 2 * NPOLS + 1) * npackets * NSAMPS + tn] = *packet++;
intermediate[( 2 * NPOLS + 2) * npackets * NSAMPS + tn] = *packet++;
intermediate[( 2 * NPOLS + 3) * npackets * NSAMPS + tn] = *packet++;
intermediate[( 3 * NPOLS + 0) * npackets * NSAMPS + tn] = *packet++;
intermediate[( 3 * NPOLS + 1) * npackets * NSAMPS + tn] = *packet++;
intermediate[( 3 * NPOLS + 2) * npackets * NSAMPS + tn] = *packet++;
intermediate[( 3 * NPOLS + 3) * npackets * NSAMPS + tn] = *packet++;
} // tn
} // sequence number
} // channel_offset
} // tab
}