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indexed.c
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indexed.c
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#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "constants.h"
/* Lower bound on timings by a single memcpy
* gives ~1.19 seconds for 10 iterations, 1757 MB /0.11s ~= 1600 MB/s
[root@laptopjisk ~]# dmidecode -t 17
# dmidecode 3.1
Getting SMBIOS data from sysfs.
SMBIOS 3.0.0 present.
Handle 0x0039, DMI type 17, 40 bytes
Memory Device
Array Handle: 0x0038
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 8192 MB
Form Factor: Row Of Chips
Set: None
Locator: System Board Memory
Bank Locator: BANK 0
Type: LPDDR3
Type Detail: Synchronous Unbuffered (Unregistered)
Speed: 1867 MT/s
Manufacturer: Micron
Serial Number: 00000000
Asset Tag: 9876543210
Part Number: MT52L1G32D4PG-107
Rank: 2
Configured Clock Speed: 1867 MT/s
Minimum Voltage: 1.25 V
Maximum Voltage: 1.25 V
Configured Voltage: 1.2 V
*/
/**
* 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 unsigned char *} page Ringbuffer page with interleaved data
* @param {const unsigned char *} transposed Buffer with deinterleaved data
* @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 * restrict transposed, const int ntabs, const int nchannels, const int npackets) {
int packets_processed = 0;
int tab = 0;
for (tab = 0; tab < ntabs; tab++) {
int channel_offset = 0;
for (channel_offset = 0; channel_offset < nchannels; channel_offset+=4) {
int sequence_number = 0;
for (sequence_number = 0; sequence_number < npackets; sequence_number++) {
// find start of packet, and increase counter
const unsigned char * restrict packet = &page[packets_processed * NPOLS*NCHANS*NSAMPS];
packets_processed++;
// process packet
int tn,cn,pn;
#pragma omp parallel for
for (tn = 0; tn < NSAMPS; tn++) { // 500 samples per packet
for (cn = 0; cn < NCHANS; cn++) { // 4 channels per packet
for (pn = 0; pn < NPOLS; pn++) { // 4 poliarizations per packet
transposed[
((tab * nchannels + cn + channel_offset) * NPOLS + pn) * npackets * NSAMPS +
tn + sequence_number * NSAMPS
] = packet[tn * NCHANS * NPOLS + cn * NPOLS + pn];
}
}
}
}
}
}
}