#include <stdio.h>
#include <cvl/cvl.h>
/*
 * THEAD takes a CVL picture header and checks it for consistency and
 * completeness. If all is fine, 0 is returned. If some things are
 * odd, but can be fixed as stated in the cvl header description, 
 * 1 is returned. If it can not be fixed, -1 is returned.
 * If flag is true, error messages will be printed to stderr 
 * when -1 is returned.
 *  Only the following fields are checked:
 * bits-per-pixel
 * bands-per-pixel
 * sigbits-per-band
 * sigbits-per-pixel
 * bits-per-band
 *
 * Andrew Jewell        1/4/87         cc -O -c thead.c
 */

int thead (area, flag)
struct cvl_p *area;
       int   flag;
{
   int returnflag = 0;

   if (area->cv_bp <= 0) {
      if (flag)
         fprintf(stderr,"Bits per pixel <= 0\n");
      return(-1);
   }

   if (area->cv_sbp == 0) {
      if (area->cv_sbb == 0) {
         area->cv_sbb = area->cv_bb;
         returnflag = 1;
      }
      area->cv_sbp = area->cv_bp;
      returnflag = 1;
   }


   if ((area->cv_bnds * area->cv_bb) > area->cv_bp) {
      if (flag)
         fprintf(stderr,"bands*bits-per-band exceeds bits-per-pixel\n");
      return(-1);
   }

   if ((area->cv_bnds * area->cv_bb) > area->cv_sbp) {
      area->cv_sbp = area->cv_bb * area->cv_bnds;
      returnflag = 1;
   }

   if (area->cv_bp < area->cv_sbp) {
      area->cv_sbp = area->cv_bp;
      returnflag = 1;
   }

   if (area->cv_bb < area->cv_sbb) {
      area->cv_sbb = area->cv_bb;
      returnflag = 1;
   }

   return(returnflag);
}