MATLAB toolbox for Brain-Computer Interfacing (BCI).zip

/* read_bv.c This file defines a mex-Function to load an eeg-File from a location. data = read_bv(file, HDR, OPT); read_bv(file, HDR, OPT); / with opt.data and opt.dataPos set Arguments: file - Name of EEG file (.eeg) is appended) HDR - Information about the file (read from the *.vhdr header file) .fs - Sampling rate .nChans - Number of channels .nPoints - Number of data points in the file (optional) .scale - Scaling factors for each channel .endian - Byte ordering: 'l' little or 'b' big OPT - Struct with following fields .chanidx - Indices of the channels that are to be read .fs - Down sample to this sampling rate .filt_b - Filter coefficients of IIR filter applied to raw data (b part) (optional) .filt_a - Filter coefficients of IIR filter applied to raw data (a part) (optional) .filt_subsample - Filter coefficients of FIR filter used for sub sampling (optional) .data - A matrix where the data is stored (optional) .dataPos - The position in the matrix[dataStart dataEnd fileStart fileend](optional) The filter parts of the OPT structure are optional fields. The default for the filt_subsample is a filter which takes the last value of filtered block e.g. [0 ... 0 1] 2008/04/07 - Max Sagebaum - file created 2008/04/25 - Max Sagebaum - the char buffer was allocated with mxCalloc and freed this was wrong I changed it to malloc 2008/05/20 - Max Sagebaum - checked for linux compatibly - fixed some errors in argument checking 2008/06/20/ - Max Sagebaum - added option to load data into matrix (c) Fraunhofer FIRST.IDA 2008 */ #include <stdio.h> #include "mex.h" /* * Define statements */ #define INT_16_SIZE 2 /* sizeof(short) */ #define mwSize int /* not available in Matlab 6 */ /* the field names for HDR and OPT*/ const char *FS_FIELD = "fs"; const char *N_CHANS_FIELD = "nChans"; const char *N_POINTS_FIELD = "nPoints"; const char *SCALE_FIELD = "scale"; const char *ENDIAN_FIELD = "endian"; const char *CHAN_ID_X_FIELD = "chanidx"; const char *FILT_A_FIELD = "filt_a"; const char *FILT_B_FIELD = "filt_b"; const char *FILT_SUBSAMPLE_FIELD = "filt_subsample"; const char *DATA = "data"; const char *DATA_POS = "dataPos"; /* the handle for the eeg-file */ static FILE *eegFile; /* hdr data values */ static double rawDataSamplingRate; static int rawDataChannelCount; static double *rawDataScale; static char rawDataEndian; static int rawDataPoints; /* opt non optional values */ static double *optChannelSelect; static int optChannelSelectCount; static double optSamplingRate; /* the values for the IIR filter */ static int iirFilterSize = 0; /* the size of the IIR filter */ static int iirFilterOffset = 0; /* we access the buffers toroidal */ static double *bFilter; /* the b part of the IIR filter */ static double *aFilter; /* the a part of the IIR filter */ static double *xBuffer; /* the buffer for the unfiltered values */ static double *yBuffer; /* the buffer for the filtered values */ /* the values for the FIR filter */ static double *firFilter; /* a filter for the re sampling of the data */ static int firFilterPosition; /* the position in the filter */ static int firFilterSize; /* the size of the filter */ static double firFilterSum; /* the sum of the values in the filter */ static double *firFilterValues; /* the current values for the re sampling */ /* the positions of the samples when we write in a matrix*/ static double* dataPtr; static int dataPtrSize; /* the number of rows in the data */ static int dataStart; /* the position of the first sample in the data*/ static int dataEnd; /* the position of the last sample in the data*/ static int fileStart; /* the first position of the data in the file*/ static int fileEnd; /* the last position of the data in the file*/ /* * FORWARD DECLARATIONS */ static void rbv_init(int nrhs,const mxArray *prhs[]); static bool rbv_readDataBlock(double *dataBlock, short* dataBuffer, int channelCount ,bool swap); static void rbv_readData( int nlhs, mxArray *plhs[]); static double rbv_filterDataIIR(double value, int channel) ; static void rbv_cleanup(); static void rbv_assert(bool aValue,const char* text); /************************************************************ * * mexFunction * ************************************************************/ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) { /* First check of argument counts and output */ rbv_assert(nrhs == 3, "Exactly three input arguments required."); rbv_assert(nlhs <= 1, "One or two output arguments required."); /* check the argument values and setup the filter, values, ... */ rbv_init(nrhs,prhs); rbv_readData(nlhs,plhs); rbv_cleanup(); } /************************************************************* * * a quick and dirty solution for the file size * I got it from http:/*bytes.com/forum/thread221370.html * They mention that it will work with binary data(which is fine for us) * but not with textual data. * * The function is only used, when HDR.nPoints was not set * * returns the length of a file (in bytes) * *************************************************************/ static int file_length(FILE *f) { int pos; int end; pos = ftell (f); fseek (f, 0, SEEK_END); end = ftell (f); fseek (f, pos, SEEK_SET); return end; } /************************************************************ * * Checks if the input values are valid and sets up the values * for reading the eeg-file * ************************************************************/ static void rbv_init(int nrhs, const mxArray *prhs[]) { const mxArray *FILE_NAME; const mxArray *HDR; const mxArray *OPT; mxArray *tempPointer; bool isAFilter, isBFilter; /* to check if filt_a and filt_b was set */ int lag; /* the difference between the sampling rate of the raw data and and the sampling rate of the requested data */ int i; /* temp counting value */ double* tempDataPtr; /* pointer for OPT.dataPos */ char *charBuf; /* buffer for char reading (please free after usage) */ mwSize charBufLength; /* the size of the buffer */ /* * opening the eeg file */ FILE_NAME = prhs[0]; charBufLength = mxGetNumberOfElements(FILE_NAME) + 1; charBuf = malloc(charBufLength * sizeof(char)); if (mxGetString(FILE_NAME, charBuf, charBufLength) != 0) { free(charBuf); charBuf = 0; mexErrMsgTxt("Could not read file name."); return; } eegFile = fopen(charBuf,"rb"); /* only r will cause an error rb stands */ /* for read binary */ rbv_assert(NULL != eegFile, "Could not open eeg file."); free(charBuf); charBuf = 0; /* * HDR loading */ HDR = prhs[1]; rbv_assert(mxIsStruct(HDR),"HDR has to be a struct."); /* see if we have our fields */ rbv_assert(mxGetFieldNumber(HDR,FS_FIELD) != -1,"The field HDR.fs was not set"); rbv_assert(mxGetFieldNumber(HDR,N_CHANS_FIELD) != -1,"The field HDR.nChans was not set"); rbv_assert(mxGetFieldNumber(HDR,SCALE_FIELD) != -1,"The field HDR.scale was not set"); rbv_assert(mxGetFieldNumber(HDR,ENDIAN_FIELD) != -1,"The field HDR.endian was not set"); /* * load the field HDR.fs */ tempPointer = mxGetField(HDR,0,FS_FIELD); rbv_assert(mxIsNumeric(tempPointer), "HDR.fs must b