diff saitools/trigger.c @ 0:5242703e91d3 tip

Initial checkin for AIM92 aimR8.2 (last updated May 1997).

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/saitools/trigger.c	Fri May 20 15:19:45 2011 +0100
@@ -0,0 +1,136 @@
+/*
+    Copyright (c) Applied Psychology Unit, Medical Research Council. 1993
+    ===========================================================================
+
+    Permission to use, copy, modify, and distribute this software without fee 
+    is hereby granted for research purposes, provided that this copyright 
+    notice appears in all copies and in all supporting documentation, and that 
+    the software is not redistributed for any fee (except for a nominal 
+    shipping charge). Anyone wanting to incorporate all or part of this 
+    software in a commercial product must obtain a license from the Medical 
+    Research Council.
+
+    The MRC makes no representations about the suitability of this 
+    software for any purpose.  It is provided "as is" without express or 
+    implied warranty.
+ 
+    THE MRC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING 
+    ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL 
+    THE A.P.U. BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES 
+    OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, 
+    WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, 
+    ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 
+    SOFTWARE.
+*/
+
+/* trigger.c
+*
+* Part of the temporal regularity programs
+*
+* M.Akeroyd. Summer 1993. Revised Winter 1994.
+*/
+
+
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+#include "tip.h"
+
+
+
+
+extern struct Peak peak[MAX_PEAKS];    /* all channels */
+
+extern int framewidth_samples;      /* pwidth + nwidth * samplerate */
+extern int pwidth;                  /* in msecs */
+extern int nwidth;                  /* in msecs: NEGATIVE */
+extern int samplerate;              /* samples per sec */
+
+
+extern char progname[MAX_STRING_LENGTH];
+
+
+
+
+
+
+int find_trigger(int frame, int channel, int total_peaks)
+{
+
+  /* What this code does: 
+   * 
+   * it looks for trigger peaks, at or near ImageTime = 0.
+   * First, it looks for a peak reasonably
+   * close to where the trigger-peak SHOULD be. If there isn't one there, then it reports 
+   * a failure, and crashes.
+   * (No it doesn't: in fact it takes the fisrt peak to the right of the pre-defined trigger point).
+   *
+   * The peaknumber of the trigger_peak is RETURNed.
+   *
+   * Version of 1st June 1993.
+   */
+
+
+  int n_1; 
+  int channel_1;
+  int trigger_sample;       /* where the trigger of channel_1 is */
+  double trigger_double;
+  int trigger_found = OFF;
+  int trigger_peak;          /* THIS IS RETURNED */
+
+
+  /* hack ... */
+  if (total_peaks == 0)
+    return 0;
+
+  /* First, find out where the trigger-point is :
+   * pwidth is in msecs, so divide that by 1000, multiply by sample, and you get pwidth in 
+   * samples.
+   * So, trigger = that - 1 (-1 because the indexing is 0 to (framewidth_samples -1)) 
+   * Hope this integer arithemetic works */
+
+  trigger_double = (double) ((double) pwidth * (double) samplerate) / 1000.0 - 1;
+  trigger_sample = (int) trigger_double;
+  n_1 = total_peaks + 1;
+
+  /* find first peak to RIGHT of trigger (reverse, remember) */
+  while ((peak[--n_1].sample < trigger_sample)) 
+    ;
+
+  /* the next peak will be the trigger, at least on today's definition */
+  trigger_found  = ON;
+  trigger_sample = peak[n_1].sample;
+  trigger_peak = n_1; 
+  
+  if (trigger_found == OFF ) {
+    fprintf(stderr, "%s: unable to find trigger point: frame  %i  channel %i\n", progname, frame, channel_1);
+    exit(-1);}
+
+  return trigger_peak;
+}
+
+
+
+/* The End .........................................................................*/
+/*..................................................................................*/
+
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