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/*
Copyright (C) 2010 EPFL (Ecole Polytechnique Fédérale de Lausanne)
Laboratory CNBI (Chair in Non-Invasive Brain-Machine Interface)
Nicolas Bourdaud <nicolas.bourdaud@epfl.ch>
This program 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, either version 3 of the License, or
(at your option) any later version.
This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
/* Example : create_bdf.c
*
* This program demonstrates how to write a BDF file. In particular it shows
* how to initialize a xDF file, and setup the channels and feed the data
*
* It creates 3 blocks of channels:
* - NEEG channels containing each a sine wave of 1 to NEEG Hz of float
* - NSENS channels containing each a sine wave of 1 to NSENS Hz of double
* - 1 channel containing a integer value of 0xF0 every 0.5 seconds
*/
#include <stdint.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <xdfio.h>
#include <math.h>
const char filename[] = "signal.bdf";
#define NS 8
#define NEEG 64
#define NSENS 8
#define FS 512
#define DURATION 10
#define TOTAL_NS (FS*DURATION)
/* Buffers holding the data to be written on the file */
#define NARRAYS 3
float eeg[NS*NEEG];
double sens[NS*NSENS];
int32_t trigger[NS];
const char eeglabels[64][8] = {
"Fp1", "AF7", "AF3", "F1", "F3", "F5", "F7", "FT7",
"FC5", "FC3", "FC1", "C1", "C3", "C5", "T7", "TP7",
"CP5", "CP3", "CP1", "P1", "P3", "P5", "P7", "P9",
"PO7", "PO3", "O1", "Iz", "Oz", "POz", "Pz", "CPz",
"Fpz", "Fp2", "AF8", "AF4", "AFz", "Fz", "F2", "F4",
"F6", "F8", "FT8", "FC6", "FC4", "FC2", "FCz", "Cz",
"C2", "C4", "C6", "T8", "TP8", "CP6", "CP4", "CP2",
"P2", "P4", "P6", "P8", "P10", "PO8", "PO4", "O2"
};
const char senslabels[8][8] = {
"EXG1", "EXG2", "EXG3", "EXG4", "EXG5", "EXG6", "EXG7", "EXG8"
};
const char stepmsg[][128] = {
"creating the file",
"configuring the channels",
"preparing the transfer",
"writing the data"
};
static int generate_signal(unsigned int neeg, float *eeg,
unsigned int nsens, double* sens,
int32_t* triggers,
float ffs, unsigned int ns)
{
unsigned int j, i;
static int k = 0;
for (j=0; j<ns; j++) {
for (i=0; i<neeg; i++)
eeg[j*neeg+i] = sin(6.28*(i+1)*(j+k)/ffs);
for (i=0; i<nsens; i++)
sens[j*nsens+i] = sin((6.28*(i+1)*(j+k)/ffs));
triggers[j] = (j+k % (int)(ffs/2.0)) ? 0 : 0xF0;
}
k += ns;
return ns;
}
int configure_channels(struct xdf* xdf, unsigned int neeg, unsigned int nsens)
{
unsigned int i;
struct xdfch* ch = NULL;
/* Set the default settings of the next channels.
There is no need to setup the stored data type (XDF_CF_STOTYPE)
neither the digital min or max since BDF supports only int24 data
type and those settings are thus set by default */
xdf_set_conf(xdf, XDF_CF_ARRTYPE, XDFFLOAT,
XDF_CF_ARRINDEX, 0,
XDF_CF_ARROFFSET, 0,/* starting offset (will be
automatically incremented
after a channel is added) */
XDF_CF_TRANSDUCTER, "Active Electrode",
XDF_CF_PREFILTERING, "HP: DC; LP: 100 Hz",
XDF_CF_PMIN, -2.0,
XDF_CF_PMAX, 2.0,
XDF_CF_UNIT, "uV",
XDF_CF_RESERVED, "EEG",
XDF_NOF);
/* Add EEG channels */
for (i = 0; i < neeg; i++)
if (xdf_add_channel(xdf, eeglabels[i]) == NULL)
return -1;;
/* Setup and add sensor channels */
xdf_set_conf(xdf, XDF_CF_ARRTYPE, XDFDOUBLE,
XDF_CF_ARRINDEX, 1,
XDF_CF_ARROFFSET, 0,
XDF_NOF);
for (i = 0; i < nsens; i++)
if (xdf_add_channel(xdf, senslabels[i]) == NULL)
return -1;
/* Add and setup trigger channel
(show another way to setup a channel) */
ch = xdf_add_channel(xdf, "Status");
if (ch == NULL)
return -1;
xdf_set_chconf(ch, XDF_CF_ARRTYPE, XDFINT32,
XDF_CF_ARRINDEX, 2,
XDF_CF_ARROFFSET, 0,
XDF_CF_TRANSDUCTER, "Triggers and Status",
XDF_CF_PREFILTERING, "No filtering",
XDF_CF_PMIN, -8388608.0,
XDF_CF_PMAX, 8388607.0,
XDF_CF_UNIT, "Boolean",
XDF_CF_RESERVED, "TRI", XDF_NOF);
return 0;
}
int main(int argc, char *argv[])
{
(void) argc;
(void) argv;
struct xdf *xdf = NULL;
int step, retval = EXIT_FAILURE;
unsigned int ns, i;
size_t strides[NARRAYS] = {
NEEG*sizeof(eeg[0]),
NSENS*sizeof(sens[0]),
sizeof(trigger[0])
};
/*************************************************
* File preparation *
*************************************************/
step = 0;
xdf = xdf_open(filename, XDF_WRITE, XDF_BDF);
if (xdf == NULL)
goto exit;
xdf_set_conf(xdf, XDF_F_SAMPLING_FREQ, FS, XDF_NOF);
step++;
if (configure_channels(xdf, NEEG, NSENS))
goto exit;
step++;
if (xdf_define_arrays(xdf, NARRAYS, strides)
|| xdf_prepare_transfer(xdf) )
goto exit;
/************************************************
* Writing loop *
*************************************************/
step++;
for (i=0; i<TOTAL_NS; i+=NS) {
ns = ((TOTAL_NS - i) >= NS) ? NS : (TOTAL_NS - i);
generate_signal(NEEG, eeg, NSENS, sens, trigger, FS, ns);
if (xdf_write(xdf, ns, eeg, sens, trigger) < 0)
goto exit;
}
retval = EXIT_SUCCESS;
exit:
if (retval != EXIT_SUCCESS) {
fprintf(stderr, "Error while %s : (%i) %s\n",
stepmsg[step], errno, strerror(errno));
}
xdf_close(xdf);
return retval;
}
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