/* --------------------------------------------------------------------- 
** Figure 18.20:  Declarations for the skylight controller: skylight.h.
** Figure 18.21:  A skylight controller.
** Figure 18.22:  Operations for the skylight controller.
** --------------------------------------------------------------------- 
*/
#include "tools.h"

/* -----------------------------------------------------------------
** Definitions of the registers on the multifunction chip
*/
typedef struct REG_BYTE {
  unsigned int : 4;
  unsigned int fully_open : 1;
  unsigned int fully_closed : 1;
  unsigned int motor_power : 1;
  unsigned int motor_direction : 1;
} reg_byte;

typedef volatile reg_byte* device_pointer;

/* -----------------------------------------------------------------
** Definitions of the codes for the multifunction chip
*/
enum power_values      { motor_off = 0,     motor_on = 1 };
enum direction_values  { motor_forward = 0, motor_reverse = 1 };

string 
position_labels[] = { "fully closed", "partially open", "fully open" };
typedef enum { fully_closed, part_open, fully_open } position;

/* -----------------------------------------------------------------
** Attach to hardware addresses and create initialization constants.
*/
device_pointer const DR  = (device_pointer)0xffff7100;
device_pointer const DDR = (device_pointer)0xffff7101;
const reg_byte DDR_mask = {0,0,1,1}; /* select output bits */
const reg_byte DR_init = {0,0,0,0};  /* initialize motor off */

/* -----------------------------------------------------------------
** Prototypes for the control operations. 
*/
position skylight_status( void );
void open_skylight( void );
void close_skylight( void );

/* ---------------------------------------------------------------- */
void main( void )
{
    char choice;
    string menu[] = { "O: Open skylight", "C: Close skylight", 
                      "R: Report on position", "Q: Quit" };

    /* Initialize chip registers used by application. ------ */
    *DDR = DDR_mask;     /* Designate input and output bits. */
    *DR = DR_init;       /* Make sure motor is turned off.   */
   
    for (;;) {
        choice = toupper( menu_c( " Select operation:", 4, menu ) );
        if (choice == 'Q') break;
        switch (choice) {
          case 'O': open_skylight();          break;
          case 'C': close_skylight();         break;
          case 'R': /* Report on position */
                printf ( " Louver is %s\n", position_labels[skylight_status()] );             
                                              break; 
          default: puts( " Incorrect choice, try again." ); 
        }
    }
    puts( " Skylight controller terminated.\n" ); 
}

/* -----------------------------------------------------------------
** Return skylight position
*/ 
position
skylight_status( void )
{
  if (DR->fully_closed) return fully_closed;
  else if (DR->fully_open) return fully_open;
       else return part_open;
}

/* ----------------------------------------------------------------
** Open skylight
*/
void
open_skylight( void )
{
  reg_byte dr = { 0, 0, motor_on, motor_forward };

  if (DR->fully_open) return;   /* don't start motor if already open */
  *DR = dr;
  while (!(DR->fully_open));    /* delay until open */
  dr.motor_power = motor_off;
  *DR = dr;
}

/* ----------------------------------------------------------------
** Close skylight
*/
void
close_skylight( void )
{
  reg_byte dr = { 0, 0, motor_on, motor_reverse };

  if (DR->fully_closed) return;   /* don't start motor if already closed */
  *DR = dr;
  while (!(DR->fully_closed));    /* delay until closed */
  dr.motor_power = motor_off;
  *DR = dr;
}


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