#include "stdio.h"
#include "stdlib.h"
#include "math.h"
  
/*
   Minimal conversion program of Westmead EEG files to ascii
   The output file is as follows
   First line:      nchannels adcrate nevents nsamples
   Second line:     "sample event elec_1 elec_2 .... elec_nchannels"
   Rest of file:    sample event# sample_1 sample_2 .... sample_nchannels

   Note: this program is more complicated than it woul dneed to be if
   it was running from a PeeCee (or at least from a machine with the
   same byte ordering. In that case the binary data coule be read with
   a single "fread()". This code is primarily for UNIX machines with the
   opposite byte ordering to PeeCees, for example, an SGI.
*/

/* Prototytpes */
int ReadShort(FILE *, short int *, int);
void SkipLine(FILE *);

#define TRUE  1
#define FALSE 0

int main(int argc,char **argv)
{
   int c,i,j,readok,offset,nevent=0,nchannels,adc;
   short event,channels[200];
   long filesize=0;
   long nsamples;
   char s[128],label[128];
   FILE *fptr;

   /* Do we have enough arguments */
   if (argc < 2) {
      fprintf(stderr,"Usage: %s filename\n",argv[0]);
      exit(0);
   }

   /* Attempt to open the file */
   if ((fptr = fopen(argv[1],"r")) == NULL) {
      fprintf(stderr,"Unable to open file <%s>\n",argv[1]);
      exit(0);
   }
   
   /* 
      Calculate the file size.
      There are better "non portable" ways of doing this 
   */
   while ((c = fgetc(fptr)) != EOF)
      filesize++;

   /* 
      Check the header 
      label should be "EEG2"
   */
   rewind(fptr);
   for (i=0;i<32;i++) {
      s[i] = fgetc(fptr);
      s[i+1] = '\0';
   }
   if (sscanf(s,"%s %d",label,&offset) != 2) {
      fprintf(stderr,"Failed to read identifer and offset\n");
      exit(0);
   }

   /* Read the number of channels */
   rewind(fptr);
   nchannels = 0;
   while (fscanf(fptr,"%s",s) == 1) {
      if (strstr(s,"NumChans") != NULL) {
         SkipLine(fptr);
         SkipLine(fptr);
         SkipLine(fptr);
         SkipLine(fptr);
         fscanf(fptr,"%s %d",s,&nchannels);
         break;
      }
   }
   nchannels--;      /* Last channel holds the events */
   if (nchannels < 10) {
      fprintf(stderr,"Unexpected number of channels <%d>\n",nchannels);
      exit(0);
   }
   printf("%d ",nchannels);

   /* Read the ADC rate */
   rewind(fptr);
   adc = 0;
   while (fscanf(fptr,"%s",s) == 1) {
      if (strstr(s,"[SamRate") != NULL) {
         SkipLine(fptr);
         SkipLine(fptr);
         SkipLine(fptr);
         SkipLine(fptr);
         fscanf(fptr,"%s %d",s,&adc);
         break;
      }
   }
   if (adc < 10) {
      fprintf(stderr,"Unexpected ADC rate <%d>\n",adc);
      exit(0);
   }
   printf("%d ",adc);

   /* Determine the number of events, not done correctly! */
   printf("%d ",nevent);

   /* Calculate the number of expected samples */
   nsamples = (filesize - 512*offset) / (2*(nchannels + 1));
   printf("%ld\n",nsamples);
   if (nsamples < 1) {
      fprintf(stderr,"Unexpected number of samples <%ld>\n",nsamples);
      exit(0);
   }

   /* Read the electrode names */
   printf("sample event ");
   rewind(fptr);
   while (fscanf(fptr,"%s",s) == 1) {
      if (strstr(s,"[Label") != NULL) {
         SkipLine(fptr);
         SkipLine(fptr);
         SkipLine(fptr);
         SkipLine(fptr);
         for (i=0;i<nchannels;i++) {
            if (fscanf(fptr,"%s %s",s,label) != 2) {
               fprintf(stderr,"Error reading channel names\n");
               exit(0);
            }
            printf("%s ",label);
         }
         break;
      }
   }
   printf("\n");

   /* Read past the header */
   rewind(fptr);
   for (i=0;i<512*offset;i++)
      c = fgetc(fptr);

   /* Read the samples and write results */
   for (i=0;i<nsamples;i++) {

      /* The first column is the sample counter */
      printf("%ld ",i);

      for (j=0;j<nchannels;j++) {
         if (!ReadShort(fptr,&channels[j],TRUE)) {
            fprintf(stderr,"Error reading the %ldth sample\n",i);
            exit(0);
         }
      }
      if (!ReadShort(fptr,&event,TRUE)) {
         fprintf(stderr,"Error reading the %ldth event\n",i);
         exit(0);
      }

      /* The second column is the event flag */
      printf("%d ",event);

      /* The remaining channels are the samples */
      for (j=0;j<nchannels;j++) 
         printf("%d ",channels[j]);

      printf("\n");
   }

   fclose(fptr);
}

void SkipLine(FILE *fptr)
{
   int c;

   while ((c = fgetc(fptr)) != '\n' && c != EOF)
      ;
}

/*
   Change this depending on whether you need byte swapping or not.
   The following work on SGI and machines with the opposite byte
   ordering to a PeeCee.
*/
int ReadShort(FILE * fptr,short int *n,int swap)
{
   unsigned char *cptr,tmp;

   if (fread(n,2,1,fptr) != 1)
      return(FALSE);
   if (swap) {
      cptr = (unsigned char *)n;
      tmp = cptr[0];
      cptr[0] = cptr[1];
      cptr[1] = tmp;
   }
   return(TRUE);
}