Index: /branches/eam_branches/ipp-20151113/Ohana/src/dvomerge/Makefile
===================================================================
--- /branches/eam_branches/ipp-20151113/Ohana/src/dvomerge/Makefile	(revision 39200)
+++ /branches/eam_branches/ipp-20151113/Ohana/src/dvomerge/Makefile	(revision 39201)
@@ -172,7 +172,9 @@
 $(SRC)/SetSignals.$(ARCH).o \
 $(SRC)/Shutdown.$(ARCH).o \
+$(SRC)/LoadImages.$(ARCH).o \
 $(SRC)/dvoutils.$(ARCH).o \
 $(SRC)/dvoutils_args.$(ARCH).o \
 $(SRC)/dvoutils_uniq_images.$(ARCH).o \
+$(SRC)/dvoutils_check_images.$(ARCH).o \
 $(SRC)/dvoutils_load_image_index.$(ARCH).o
 
Index: /branches/eam_branches/ipp-20151113/Ohana/src/dvomerge/include/dvoutils.h
===================================================================
--- /branches/eam_branches/ipp-20151113/Ohana/src/dvomerge/include/dvoutils.h	(revision 39200)
+++ /branches/eam_branches/ipp-20151113/Ohana/src/dvomerge/include/dvoutils.h	(revision 39201)
@@ -20,4 +20,5 @@
   DVOUTILS_NONE,
   DVOUTILS_UNIQ_IMAGES,
+  DVOUTILS_CHECK_IMAGES,
 } DVOUTILS_OP_TYPE;
 
@@ -32,8 +33,11 @@
 
 char *IMAGES_LIST;
+char *CATDIR;
+char *EXTERN_ID_LIST;
 
 int main (int argc, char **argv);
 int dvoutils_args (int *argc, char **argv);
 int dvoutils_uniq_images (char *filename);
+int dvoutils_check_images (void);
 
 ImageData *dvoutils_load_image_index (char *filename);
Index: /branches/eam_branches/ipp-20151113/Ohana/src/dvomerge/src/dvoutils.c
===================================================================
--- /branches/eam_branches/ipp-20151113/Ohana/src/dvomerge/src/dvoutils.c	(revision 39200)
+++ /branches/eam_branches/ipp-20151113/Ohana/src/dvomerge/src/dvoutils.c	(revision 39201)
@@ -13,4 +13,8 @@
       exit (0);
 
+    case DVOUTILS_CHECK_IMAGES:
+      dvoutils_check_images();
+      exit (0);
+
     default:
       fprintf (stderr, "ERROR: unknown option\n");
Index: /branches/eam_branches/ipp-20151113/Ohana/src/dvomerge/src/dvoutils_args.c
===================================================================
--- /branches/eam_branches/ipp-20151113/Ohana/src/dvomerge/src/dvoutils_args.c	(revision 39200)
+++ /branches/eam_branches/ipp-20151113/Ohana/src/dvomerge/src/dvoutils_args.c	(revision 39201)
@@ -22,4 +22,19 @@
     remove_argument (N, argc, argv);
   }
+  if ((N = get_argument (*argc, argv, "-check-images"))) {
+    DVOUTILS_OP = DVOUTILS_CHECK_IMAGES;
+    remove_argument (N, argc, argv);
+    CATDIR = strcreate (argv[N]);
+    remove_argument (N, argc, argv);
+    EXTERN_ID_LIST = strcreate (argv[N]);
+    remove_argument (N, argc, argv);
+  }
+
+  if (*argc != 1) {
+    fprintf (stderr, "USAGE: dvoutils -uniq-images (filename) [-v,-verbose]\n\n");
+    fprintf (stderr, "USAGE: dvoutils -check-images (catdir) (externIDs) [-v,-verbose]\n\n");
+    fprintf (stderr, "  -v : VERBOSE\n");
+    exit (2);
+  }
 
   if (DVOUTILS_OP == DVOUTILS_NONE) {
@@ -28,10 +43,4 @@
   }
 
-  if (*argc != 1) {
-    fprintf (stderr, "USAGE: dvoutils -uniq-images (filename) [-v,-verbose]\n\n");
-    fprintf (stderr, "  -v : VERBOSE\n");
-    exit (2);
-  }
-
   return TRUE;
 }
Index: /branches/eam_branches/ipp-20151113/Ohana/src/dvomerge/src/dvoutils_check_images.c
===================================================================
--- /branches/eam_branches/ipp-20151113/Ohana/src/dvomerge/src/dvoutils_check_images.c	(revision 39201)
+++ /branches/eam_branches/ipp-20151113/Ohana/src/dvomerge/src/dvoutils_check_images.c	(revision 39201)
@@ -0,0 +1,256 @@
+# include "dvoutils.h"
+
+static off_t *externIDs = NULL;
+static off_t *externIDc = NULL;
+
+# define STRFAIL { fprintf (stderr, "failure on image %s\n", image[i].name); continue; }
+
+void osort (off_t *value, off_t N);
+off_t load_extern_ids (char *idfile, off_t *nids);
+off_t externIDs_bisection (off_t *values, off_t threshold, off_t Nvalues);
+Image *LoadImages (FITS_DB *db, char *filename, off_t *Nimage);
+
+int dvoutils_check_images (void) {
+
+  FITS_DB db;  // database handle pointing to input image table
+
+  off_t i, k, Nimage;
+  
+  Image *image;
+
+  // load the extern_id table
+  off_t NexternIDs = 0;
+  load_extern_ids (EXTERN_ID_LIST, &NexternIDs);
+  fprintf (stderr, "loaded "OFF_T_FMT" extern IDs\n", NexternIDs);
+
+  char imageFilename[DVO_MAX_PATH];
+
+  snprintf (imageFilename, DVO_MAX_PATH, "%s/Images.dat", CATDIR);
+
+  if ((image = LoadImages (&db, imageFilename, &Nimage)) == NULL) {
+    fprintf (stderr, "error loading images\n");
+    exit (1);
+  }
+  fprintf (stderr, "loaded "OFF_T_FMT" images\n", Nimage);
+
+  off_t NzeroIDs = 0;
+  off_t Nfound = 0;
+  off_t Nmissed = 0;
+  off_t Nextmiss = 0;
+  off_t Nextdups = 0;
+
+  off_t *imageIDs = NULL;
+  off_t *imageIDc = NULL;
+  ALLOCATE (imageIDs, off_t, Nimage);
+  ALLOCATE (imageIDc, off_t, Nimage);
+  for (i = 0; i < Nimage; i++) {
+    imageIDs[i] = image[i].externID;
+    imageIDc[i] = 0;
+  }
+  osort (imageIDs, Nimage);
+
+  for (i = 0, k = 0; (i < Nimage) && (k < NexternIDs); ) {
+
+    // skip zero-valued imageIDs 
+    if (imageIDs[i] == 0) {
+      NzeroIDs ++;
+      i++;
+      continue;
+    }
+
+    // we have either found this one or not, but it is time to move on
+    if (imageIDs[i] < externIDs[k]) { i++; continue; }
+
+    // try the next extern ID
+    if (imageIDs[i] > externIDs[k]) { k++; continue; }
+    
+    // we now have imageIDs[i] == externIDs[k].  
+    // find all imageIDs which match this externID:
+
+    imageIDc[i] ++;
+    externIDc[k] ++;
+
+    // by advancing imageIDs[i], I am ignoring externIDs[k] duplicates.  these are supposed to be uniq in the db
+    i++;
+  }
+
+  FILE *fmiss = fopen ("missed.txt", "w");
+  myAssert (fmiss, "failed to open missed.txt");
+
+  for (i = 0; i < Nimage; i++) {
+    if (imageIDs[i] == 0) continue;
+    if (imageIDc[i] == 0) {
+      fprintf (fmiss, OFF_T_FMT "\n", imageIDs[i]);
+      Nmissed ++;
+    }
+    if (imageIDc[i] == 1) { Nfound ++; continue; }
+    myAssert (imageIDc[i] <= 1, "impossible");
+  }
+  fclose (fmiss);
+
+  fmiss = fopen ("missed.extern.txt", "w");
+  myAssert (fmiss, "failed to open missed.extern.txt");
+
+  FILE *fdups = fopen ("duplicate.txt", "w");
+  myAssert (fdups, "failed to open duplicate.txt");
+
+  for (i = 0; i < NexternIDs; i++) {
+    if (externIDc[i] == 1) continue;
+    if (externIDc[i] == 0) {
+      fprintf (fmiss, "missing " OFF_T_FMT "\n", externIDs[i]);
+      Nextmiss ++;
+    }
+    if (externIDc[i] > 0) {
+      fprintf (fdups, "duplicate " OFF_T_FMT " " OFF_T_FMT "\n", externIDs[i], externIDc[i]);
+      Nextdups ++;
+    }
+  }
+  fclose (fdups);
+  fclose (fmiss);
+
+  fprintf (stderr, OFF_T_FMT " in catdir zero ID\n", NzeroIDs);
+  fprintf (stderr, OFF_T_FMT " in catdir found\n", Nfound);
+  fprintf (stderr, OFF_T_FMT " in catdir not found\n", Nmissed);
+  fprintf (stderr, OFF_T_FMT " in extern not found\n", Nextmiss);
+  fprintf (stderr, OFF_T_FMT " in extern duplicate\n", Nextdups);
+
+  gfits_db_free (&db);
+  free (externIDs);
+  free (externIDc);
+  free (imageIDs);
+  free (imageIDc);
+
+  free (CATDIR);
+  free (EXTERN_ID_LIST);
+
+  ohana_memdump (TRUE);
+
+  exit (0);
+}
+
+// I'm loading a table of expected extern IDs and initing a table of their count
+off_t load_extern_ids (char *idfile, off_t *nids) {
+
+  // load the extern ids
+  FILE *f = fopen (idfile, "r");
+  myAssert (f, "failed to open idfile");
+
+  off_t NBUFFER = 30000000;
+
+  char *buffer;
+  ALLOCATE (buffer, char, NBUFFER);
+
+  off_t Nids = 0;
+  off_t NIDS = 1000;
+  ALLOCATE (externIDs, off_t, NIDS);
+  ALLOCATE (externIDc, off_t, NIDS);
+
+  off_t skipFirst = TRUE;
+
+  off_t Nstart = 0;
+  off_t Ntotal = 0;
+  while (TRUE) {
+    off_t Nbytes = NBUFFER - 1 - Nstart;
+    bzero (&buffer[Nstart], Nbytes + 1);
+
+    off_t Nread = fread (&buffer[Nstart], 1, Nbytes, f);
+
+    Ntotal += Nread;
+    fprintf (stderr, "reading block: " OFF_T_FMT " " OFF_T_FMT " " OFF_T_FMT " " OFF_T_FMT "\n", Nstart, Nbytes, Nread, Ntotal);
+
+    if (ferror (f)) {
+      perror ("error reading data file");
+      break;
+    }
+    if (Nread == 0) break; // end of the file
+
+    off_t Nlines = 0;
+
+    int bufferStatus = TRUE; 
+    char *c0 = buffer; // c0 always marks the start of a line
+    while (bufferStatus) {
+      char *c1 = strchr (c0, '\n'); // find the end of this current line
+      if (!c1) {
+	Nstart = strlen (c0);
+	memmove (buffer, c0, Nstart);
+	bufferStatus = FALSE;
+	continue;
+      }
+      *c1 = 0; // mark the end of the line 
+      Nlines ++;
+
+      if (skipFirst) {
+	skipFirst = FALSE;
+	c0 = c1 + 1;
+	continue;
+      }
+
+      off_t extern_id;
+      int Nscan = sscanf (c0, OFF_T_FMT, &extern_id);
+      myAssert (Nscan == 1, "invalid line");
+
+      externIDs[Nids] = extern_id;
+      externIDc[Nids] = 0;
+      Nids ++;
+
+      if (Nids == NIDS) {
+	NIDS += 1000;
+	REALLOCATE (externIDs, off_t, NIDS);
+	REALLOCATE (externIDc, off_t, NIDS);
+      }
+      c0 = c1 + 1;
+    }
+  }
+  free (buffer);
+  fclose (f);
+
+  osort (externIDs, Nids);
+
+  *nids = Nids;
+  return TRUE;
+}
+
+// return the index of the last value < threshold 
+off_t externIDs_bisection (off_t *values, off_t threshold, off_t Nvalues) {
+
+  off_t Nlo = 0; 
+  off_t Nhi = Nvalues - 1;
+
+  if (Nvalues < 1) return (-1);
+  if (threshold < values[Nlo]) return (-1);
+
+  if (Nvalues < 2) return (0);
+  if (threshold > values[Nhi]) return (-1);
+
+  off_t N;
+  while (Nhi - Nlo > 4) {
+    N = 0.5*(Nlo + Nhi);
+    if (values[N] < threshold) {
+      Nlo = MAX(N, 0);
+    } else {
+      Nhi = MIN(N + 1, Nvalues - 1);
+    }
+  }
+  // values[Nlo] < threshold 
+  // values[Nhi] >= threshold 
+
+  for (N = Nlo; N < Nhi; N++) {
+    if (values[N] >= threshold) {
+      return (N-1);
+    }
+  }
+  return (N);
+}
+
+void osort (off_t *value, off_t N) {
+
+# define SWAPFUNC(A,B){ off_t tmp = value[A]; value[A] = value[B]; value[B] = tmp; }
+# define COMPARE(A,B)(value[A] < value[B])
+
+  OHANA_SORT (N, COMPARE, SWAPFUNC);
+
+# undef SWAPFUNC
+# undef COMPARE
+
+}
+