#! /usr/bin/env isis-script
%--------------------------------------------------------
% Program:  clear_bits
%  Author:  John Houck  <houck@space.mit.edu>
% Purpose:  clear specified status bits in an event file.
%
%   WARNING:  THE EVENT FILE IS MODIFIED IN PLACE.
%             If you want to keep the original file
%             unmodified, make a copy!
%
%  Examples:
%
%  1) To clear the afterglow bits, do:
%
%       clear_bits event_file.fits afterglow
%
%  2) To clear streak bits _and_ afterglow bits, do:
%
%       clear_bits event_file.fits afterglow streak
%
%--------------------------------------------------------

static variable Mask_Bits = Assoc_Type[];% bits
Mask_Bits["badpix"]       = 0x3 shl  4;  %  4:5
Mask_Bits["badbias"]      = 0x7 shl  6;  %  6:8
Mask_Bits["badoverclock"] = 0x3 shl  9;  %  9:10
Mask_Bits["badcorner"]    = 0xf shl 11;  % 11:14
Mask_Bits["streak"]       = 0x1 shl 15;  % 15
Mask_Bits["afterglow"]    = 0xf shl 16;  % 16:19

static define pgm_usage ()
{
   vmessage ("Usage:  clear_bits FILE mask_name [mask_name ...]");
   exit(0);
}

if (__argc < 3)
  pgm_usage ();

static define clear_status_bits (fp, mask)
{
   variable col, flags, hs;

   () = _fits_get_colnum (fp, "status", &col);
   flags = fits_read_col (fp, "status");

   flags &= ~mask;

   () = _fits_write_col (fp, col, 1, 1, flags);
   hs = sprintf ("clear_bits: mask = %x", mask);
   () = _fits_write_history (fp, hs);
}

static define get_mask (args)
{
   variable m, mask = 0;

   foreach (args)
     {
	m = strlow();
	mask |= Mask_Bits[m];
     }

   return mask;
}

variable file = __argv[1];
if (0 == is_substr (file, "[")
    and 0 == is_substr (file, "+"))
  file += "[1]";

variable fp, mask;

fp = fits_open_file (file, "w");
mask = get_mask (__argv[[2:]]);

clear_status_bits (fp, mask);

fp = 0;  % close the file