tomwalters@0: /*
tomwalters@0:     Copyright (c) Applied Psychology Unit, Medical Research Council. 1993
tomwalters@0:     ===========================================================================
tomwalters@0: 
tomwalters@0:     Permission to use, copy, modify, and distribute this software without fee 
tomwalters@0:     is hereby granted for research purposes, provided that this copyright 
tomwalters@0:     notice appears in all copies and in all supporting documentation, and that 
tomwalters@0:     the software is not redistributed for any fee (except for a nominal 
tomwalters@0:     shipping charge). Anyone wanting to incorporate all or part of this 
tomwalters@0:     software in a commercial product must obtain a license from the Medical 
tomwalters@0:     Research Council.
tomwalters@0: 
tomwalters@0:     The MRC makes no representations about the suitability of this 
tomwalters@0:     software for any purpose.  It is provided "as is" without express or 
tomwalters@0:     implied warranty.
tomwalters@0:  
tomwalters@0:     THE MRC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING 
tomwalters@0:     ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL 
tomwalters@0:     THE A.P.U. BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES 
tomwalters@0:     OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, 
tomwalters@0:     WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, 
tomwalters@0:     ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 
tomwalters@0:     SOFTWARE.
tomwalters@0: */
tomwalters@0: 
tomwalters@0: /* trigger.c
tomwalters@0: *
tomwalters@0: * Part of the temporal regularity programs
tomwalters@0: *
tomwalters@0: * M.Akeroyd. Summer 1993. Revised Winter 1994.
tomwalters@0: */
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: #include <stdio.h>
tomwalters@0: #include <string.h>
tomwalters@0: #include <stdlib.h>
tomwalters@0: 
tomwalters@0: #include "tip.h"
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: extern struct Peak peak[MAX_PEAKS];    /* all channels */
tomwalters@0: 
tomwalters@0: extern int framewidth_samples;      /* pwidth + nwidth * samplerate */
tomwalters@0: extern int pwidth;                  /* in msecs */
tomwalters@0: extern int nwidth;                  /* in msecs: NEGATIVE */
tomwalters@0: extern int samplerate;              /* samples per sec */
tomwalters@0: 
tomwalters@0: 
tomwalters@0: extern char progname[MAX_STRING_LENGTH];
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: int find_trigger(int frame, int channel, int total_peaks)
tomwalters@0: {
tomwalters@0: 
tomwalters@0:   /* What this code does: 
tomwalters@0:    * 
tomwalters@0:    * it looks for trigger peaks, at or near ImageTime = 0.
tomwalters@0:    * First, it looks for a peak reasonably
tomwalters@0:    * close to where the trigger-peak SHOULD be. If there isn't one there, then it reports 
tomwalters@0:    * a failure, and crashes.
tomwalters@0:    * (No it doesn't: in fact it takes the fisrt peak to the right of the pre-defined trigger point).
tomwalters@0:    *
tomwalters@0:    * The peaknumber of the trigger_peak is RETURNed.
tomwalters@0:    *
tomwalters@0:    * Version of 1st June 1993.
tomwalters@0:    */
tomwalters@0: 
tomwalters@0: 
tomwalters@0:   int n_1; 
tomwalters@0:   int channel_1;
tomwalters@0:   int trigger_sample;       /* where the trigger of channel_1 is */
tomwalters@0:   double trigger_double;
tomwalters@0:   int trigger_found = OFF;
tomwalters@0:   int trigger_peak;          /* THIS IS RETURNED */
tomwalters@0: 
tomwalters@0: 
tomwalters@0:   /* hack ... */
tomwalters@0:   if (total_peaks == 0)
tomwalters@0:     return 0;
tomwalters@0: 
tomwalters@0:   /* First, find out where the trigger-point is :
tomwalters@0:    * pwidth is in msecs, so divide that by 1000, multiply by sample, and you get pwidth in 
tomwalters@0:    * samples.
tomwalters@0:    * So, trigger = that - 1 (-1 because the indexing is 0 to (framewidth_samples -1)) 
tomwalters@0:    * Hope this integer arithemetic works */
tomwalters@0: 
tomwalters@0:   trigger_double = (double) ((double) pwidth * (double) samplerate) / 1000.0 - 1;
tomwalters@0:   trigger_sample = (int) trigger_double;
tomwalters@0:   n_1 = total_peaks + 1;
tomwalters@0: 
tomwalters@0:   /* find first peak to RIGHT of trigger (reverse, remember) */
tomwalters@0:   while ((peak[--n_1].sample < trigger_sample)) 
tomwalters@0:     ;
tomwalters@0: 
tomwalters@0:   /* the next peak will be the trigger, at least on today's definition */
tomwalters@0:   trigger_found  = ON;
tomwalters@0:   trigger_sample = peak[n_1].sample;
tomwalters@0:   trigger_peak = n_1; 
tomwalters@0:   
tomwalters@0:   if (trigger_found == OFF ) {
tomwalters@0:     fprintf(stderr, "%s: unable to find trigger point: frame  %i  channel %i\n", progname, frame, channel_1);
tomwalters@0:     exit(-1);}
tomwalters@0: 
tomwalters@0:   return trigger_peak;
tomwalters@0: }
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: /* The End .........................................................................*/
tomwalters@0: /*..................................................................................*/
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: 
tomwalters@0: