//RwL 1-14-2008
//
//   TraceStarts.c


//This program is based on the January-February 2007 awk script with a similar name.
// It has been modified for c and also to account for the 8000 Hz sampling in the
// Trace2_8_all2.dat file
//
//The plan is to recognize bundles of energy, basically Bill Menger's approach
// but to review the locations of the bundles making decisions as to 
// which are actually trace starts.  The traces start times from the summer
// 2006 Excel effort seemed to be a little more than 4 s apart, perhaps
// averaging somewhere in the 4.1 to 4.2 range.  Energy bundles not separated
// by this much will be deemed to be on the same trace.
//
//After the starts of the bundles are highgraded,then will be used as pointers 
// to recover the actual traces in a separate program.


//
// When this is compiled, you need to compile with large file support.  The
// following command seems to work.
//
// gcc -o TraceStarts -D_FILE_OFFSET_BITS=64 TraceStarts.c
//


#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>

int main()
{

FILE *fileIn, *fileOut;
int i, j=0;
float value[250];			//value is the input signal amplitude
double time[250];			//sample time on the tape. 
double lastStart=0.;		//this is the time of the start of the last trace.
							// The next trace must be 3+ seconds later than this time.
float sum;					//this is the energy accumulater

	// Open the data file and the output start times file
	fileOut = fopen ("Starts.dat","w");
	fileIn = fopen ("Track4_8_all2.dat","r");
	// Read in 30*8 (240) samples.  This is scaled up from the 1000 Hz that was
	// the basis of the awk script.
	for (i=1; i<=240; ++i)
		{
		 fscanf (fileIn, "%lf %e", &time[i], &value[i]); 
		} 	

	// Set up a do-while loop to step through the data file one time sample in 
	// each pass through the loop.
	do 
	{
	// Calculate the energy
	sum = 0.;
	for (i=1; i<=240; ++i)
		{
		 sum = sum + fabsf(value[i]);
		}

	// Test the energy level.  In the awk script for 1000 Hz sampling, the magic
	// threshold value was 0.85.  This was for 30 samples.  Increasing the number
	// of samples by 8x might suggest the threshold for the 8000 Hz sampling
	// should be 6.8.  Other values might be usable.

	if (sum >= 8.3 && time[1]>lastStart)
		{
		 fprintf (fileOut, "%lf\n", time[1]);
		 lastStart = time[1] + 3.8;
		 printf ("Trace %d  Time %lf  Energy %f  Last %lf\n", ++j, time[1], sum, lastStart);	 			 
		}

		// Slide the time and value elements up 1 in the arrays and
		// read in a new value for the end of the array.
		 for (i=1; i<=239; ++i)
			{
			 time[i] = time[i+1];
			 value[i] = value[i+1];
			}	
		fscanf (fileIn, "%lf %e", &time[i], &value[i]);
		

	} while (!feof(fileIn));

	fclose (fileIn);
	fclose (fileOut);
 	return 0;
} //end of main()