Good Morning,
the former message was too big for this list due to the large grid file -- what
to do with this example? The rest should be OK and explain the grid format a
bit:
> > Back in university I could attach a simple program of mine that computes
> > the averaged spectrum.
> >
>
Please see the attachment grid-spectravg.cpp, the interesting parts are
commented specially.
Yours,
--
Robb Bean <Robb underline Bean at gmx dot net>
Projects:
http://applaunch.sourceforge.net/
http://laymansys.sourceforge.net/
#include <cstdio>
#include <stdint.h>
#include <cstdlib>
#include <cstddef>
#include <climits>
uint16_t swapShort(const uint16_t s);
int main(int argc, char *argv[]) {
if (argc < 3) {
std::fprintf(stderr,
"Usage: %s FILE NUM_SPECTRA NUM_DATAPOINTS\n",
*argv);
return 1;
}
FILE *f;
uint32_t nSpectra, // number of spectra
nDataPoints; // number of data points per spectrum
if (! (f = std::fopen(argv[1], "rb"))) {
std::perror(argv[1]);
return 1;
}
// some command line handling, should be read from the parameter
// file
nSpectra = std::strtoul(argv[2], NULL, 0);
nDataPoints = std::strtoul(argv[3], NULL, 0);
if (nSpectra == 0 || nSpectra == ULONG_MAX ||
nDataPoints == 0 || nDataPoints == ULONG_MAX)
{
perror("NUM_SPECTRA or NUM_DATAPOINTS");
std::fclose(f);
return 1;
}
// The interesting part starts here:
uint16_t *frame = new uint16_t[nSpectra];
double specPoint; // one point of the spectrum
// Read the first frame containing the first spectroscopy point
// of all spectra:
std::fread(frame, sizeof(uint16_t), nSpectra, f);
for (uint32_t i = 0;
i < nDataPoints && !(std::feof(f) || std::ferror(f));
++i)
{
specPoint = 0.;
for (uint32_t j = 0; j < nSpectra; ++j) {
specPoint += swapShort(frame[j]);
// The byte swapping is only necessary
// on little endian machines. I don't know
// if windows has ntohs, so I reimplemented
// its functionality.
}
printf("%u %.8f\n", i, specPoint / nSpectra /* averaging
*/);
// TODO: Using the values from the parameter file, we here
// could compute the physical values:
//
// Parameter = Start point spectroscopy + i * Increment point
spectroscopy
// Channel = specPoint / nSpectra * Resolution
// Read the next frame:
std::fread(frame, sizeof(uint16_t), nSpectra, f);
}
delete[] frame;
std::fclose(f);
return 0;
}
uint16_t swapShort(const uint16_t s) {
static const uint16_t hi = 0xff00;
static const uint16_t lo = 0x00ff;
return ((s & hi) >> 8) | ((s & lo) << 8);
}
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