/*****************************************************************************/
/* decerror.c        Reports or changes the following shared memory (wiro.h) */
/*   variable:                                                               */
/*   #define DEC_ERR_COEFF  tinfo->dec_enc_err_coeff                         */
/*   double dec_enc_err_coeff;                                               */
/*                         a constant equal to (Dec Encoder Error / DES_DEC) */
/*  Syntax: decerror [new DEC_ERR_COEFF]                                     */
/*  Synopsis: Without the optional argument, decerror returns the current    */
/*   DEC_ERR_COEFF.  If the optional argument is provided, decerror over-    */
/*   writes the current value for DEC_ERR_COEFF with the value of the        */
/*   argument.  If the syntax or coefficient are unexpected then this help is*/
/*   printed.                                                                */
/*  Argument: a double within the range -0.005 to +0.005. Dimensionless.     */
/*   Obtained by first zeroing DEC_ERR_COEFF. Use two stars of different     */
/*   declination near zenith whose positions are well known. Center and icol */
/*   on the first. Follow the second. Offset as required to center the second*/
/*   star.  Divide the dec offset by the known distance in dec to obtain     */
/*   DEC_ERR_COEFF.                                                          */
/*  Background: Telescope gearing requires that one turn of a telescope      */
/*   encoder correspond to 0.5 degree on-sky.  Both telescope encoders are   */
/*   Heidenhain ROQ-437. Ideally, the counting periodicity of an encoder's   */
/*   digital outputs should equal the angular periodicity of an encoder's    */
/*   shaft. This is not the case for the ROQ-437. Seperate scale factors for */
/*   RA and Dec are stored within the ACU at SiteSetup>EncoderOffsetWindow.  */
/*   If the value of the scale factor is properly selected, then the         */
/*   encoder's digital periodicity will equal the encoder's shaft            */
/*   periodicity.                                                            */
/*  Diagnosis: This scaling algorithm is broken for Dec.                     */
/*  New Algorithm: When tracking utilities "follow", "fixed" or "planet"     */
/*   precipitate a slew to a new object, the trackloop pre-compensates for   */
/*   the dec encoder error by pre-loading the appropriate dec encoder-offset */
/*   within the ACU at SiteSetup>EncoderOffsetWindow.  This encoder-offset is*/
/*   calculated by multiplying DEC_EFF_COEFF times DES_DEC. The ACU adds the */
/*   encoder-offset to the actual Dec coordinate before the slew begins.  No */
/*   evidence of the offset remains after the slew is completed except within*/
/*   the SiteSetup>EncoderOffsetWindow.  The encoder-offset will be changed  */
/*   again before the next slew.                              JSW 23May2011  */
/*****************************************************************************/

#include <ctype.h>
#include <slang/slang.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <termios.h>

#include "wirotypes.h"
#include "track.h"
#include "GPIBports.h"
#include "wiro.h"

void log_entry( char *comment );
struct  wiro_memory *tinfo, *get_tinfo();

main( int argc, char *argv[] ) {

  double val;
  char	log_message[ 64 ];

  tinfo = get_tinfo();

  if( argc < 2 ) {
    printf("\n%9.6f    \n", DEC_ERR_COEFF);
    exit( 0 );
  }

  else if( argc == 2 ) {
    if( sscanf( argv[ 1 ], "%lf", &val ) != 1 ) {
      help();
      exit( 1 );
    }
    if(( val < -0.005 ) || ( +0.005 < val )) {
      printf("\nArgument is out-of-range: %s\n", argv[ 1 ]);
      help();
      exit( 2 );
    }
    DEC_ERR_COEFF = val;
    sprintf( log_message,
	   "Load new Dec encoder offset: %9.6f\n", DEC_ERR_COEFF);
    log_entry( log_message );
  }

  else if (argc > 2) {
    printf("\nToo many arguments.\n");
    help( );
    exit( 5 );
  }

  exit( 0 );
}

/* end main */


help( ) {
  printf("\ndecerror.c  Reports or changes the following shared memory\n");
  printf("  (wiro.h) variable:\n");
  printf("  #define DEC_ERR_COEFF  tinfo->dec_enc_err_coeff\n");
  printf("  double dec_enc_err_coeff;\n");
  printf("       \\* a constant equal to (Dec Encoder Error / DES_DEC) *\\\n");
  printf(" Command Syntax: decerror [new DEC_ERR_COEFF]\n");
  printf(" Synopsis: Without the optional argument, decerror returns the\n");
  printf("  current DEC_ERR_COEFF.  If the optional argument is provided,\n");
  printf("  decerror overwrites the current value for DEC_ERR_COEFF with\n");
  printf("  the value of the argument.  If the syntax or coefficient are\n");
  printf("  unexpected then this help is printed.\n");
  printf(" Argument: a double within the range -0.005 to +0.005.\n");
  printf("  Dimensionless.  Obtained by first zeroing DEC_ERR_COEFF. Use\n");
  printf("  two stars of different declination near zenith whose positions\n");
  printf("  are well known. Center and icol on the first. Follow the\n");
  printf("  second. Offset as required to center the second star.  Divide\n");
  printf("  the dec offset by the known distance in dec to obtain\n");
  printf("  DEC_ERR_COEFF.\n");
  printf(" Background: Telescope gearing requires that one turn of a\n");
  printf("  telescope encoder correspond to 0.5 degree on-sky.  Both\n");
  printf("  telescope encoders are Heidenhain ROQ-437. Ideally, the\n");
  printf("  counting periodicity of an encoder\'s digital outputs should\n");
  printf("  equal the angular periodicity of an encoder\'s shaft. This is\n");
  printf("  not the case for the ROQ-437. Seperate scale factors for RA\n");
  printf("  and Dec are stored within the ACU at\n");
  printf("  SiteSetup>EncoderOffsetWindow.  If the value of the scale\n");
  printf("  factor is properly selected, then the encoder\'s digital\n");
  printf("  periodicity will equal the encoder\'s shaft periodicity.\n");
  printf(" Diagnosis: This scaling algorithm is broken for Dec.\n");
  printf(" New Algorithm: When tracking utilities \"follow\", \"fixed\" or\n");
  printf("  \"planet\" precipitate a slew to a new object, the trackloop\n");
  printf("  pre-compensates for the dec encoder error by pre-loading the\n");
  printf("  appropriate dec encoder-offset within the ACU at\n");
  printf("  SiteSetup>EncoderOffsetWindow.  This encoder-offset is\n");
  printf("  calculated by multiplying DEC_EFF_COEFF times DES_DEC. The ACU\n");
  printf("  adds the encoder-offset to the actual Dec coordinate before\n");
  printf("  the slew begins.  No evidence of the offset remains after the\n");
  printf("  slew is completed except within the\n");
  printf("  SiteSetup>EncoderOffsetWindow.  The encoder-offset will be\n");
  printf("  changed again before the next slew.            JSW 23May2011\n\n");
}