/* C device driver header */

#ifndef I8086D
int x = WRONG_MEMORY_MODEL;
#endif

/* byte has been misspelled to prevent a conflict with DOS.H */

typedef unsigned char bite;
typedef unsigned int word;

#ifndef NULL
#define NULL 0L
#endif

/* format of device header */

struct device_header {
  struct device_header *next;
  word attributes;
  word strategy_entry;
  word interrupt_entry;
  char name[8];
  };

/* device header attributes */

#define CHAR_DEVICE_ATTRIBUTE     0x8000
#define STI_DEVICE_ATTRIBUTE      0x0001
#define STO_DEVICE_ATTRIBUTE      0x0002
#define NUL_DEVICE_ATTRIBUTE      0x0004
#define CLOCK_DEVICE_ATTRIBUTE    0x0008
#define SPECIAL_ATTRIBUTE         0x0010
#define IOCTL_ATTRIBUTE           0x4000
#define NON_IBM_FORMAT_ATTRIBUTE  0x2000

/* format of BPB (block devices only) */

struct bpb {
  word bytes_per_sector;
  bite sectors_per_allocation_unit;
  word reserved_sectors;
  bite FATs;
  word root_directory_entries;
  word total_sectors;
  bite media_descriptor;
  word sectors_per_FAT;
  word sectors_per_track;
  word heads;
  word hidden_sectors;
  };
  
/* format of request header and functional data */

struct request_header {
  bite length;
  bite unit_code;
  bite command_code;
  int status;
  bite reserved[8];
  union {
    struct {
      bite number_of_units;
      char *end_of_driver;
      union {
        char *command_line;
        struct bpb **bpb_table;
        } pointer;
      } init ;
    struct {
      bite media_descriptor;
      bite returned;
      } media_check ;
    struct {
      bite media_descriptor;
      char *transfer_address;
      struct bpb *bpb;
      } build_bpb ;
    struct {
      bite media_descriptor;
      char *transfer_address;
      word count;
      word starting_sector;
      } io ; /* for ioctl_input
                    input
                    output
                    output_with_verify
                    ioctl_output        */
    struct {
      bite character;
      } nondestructive_input ;
    } x;
  };

/* structure used by date_and_time() function */

struct date_and_time {
  word days;
  bite minutes;
  bite hours;
  bite hundredths;
  bite seconds;
  };

/* status bits returned by driver */

#define ERROR_STATUS  0x8000
#define BUSY_STATUS   0x0200
#define DONE_STATUS   0x0100

/* error numbers added to ERROR_STATUS */

#define WRITE_PROTECT_VIOLATION             0
#define UNKNOWN_UNIT                        1
#define DRIVE_NOT_READY                     2
#define UNKNOWN_COMMAND                     3
#define CRC_ERROR                           4
#define BAD_DRIVE_REQUEST_STRUCTURE_LENGTH  5
#define SEEK_ERROR                          6
#define UNKNOWN_MEDIA                       7
#define SECTOR_NOT_FOUND                    8
#define PRINTER_OUT_OF_PAPER                9
#define WRITE_FAULT                         10
#define READ_FAULT                          11
#define GENERAL_FAILURE                     12

/* functions that must be defined in driver */

extern void init(void);
extern void media_check(void);
extern void build_bpb(void);
extern void ioctl_input(void);
extern void input(void);
extern void nondestructive_input(void);
extern void input_status(void);
extern void input_flush(void);
extern void output(void);
extern void output_with_verify(void);
extern void output_status(void);
extern void output_flush(void);
extern void ioctl_output(void);

/* external items defined in startup code */

extern void bad_device_driver_function(void);
extern struct request_header *request_header;
extern struct device_header *device_header;
extern void exit(void);

/* external items defined in other modules */

extern int date_and_time(struct date_and_time *);
extern void call_driver(struct device_header *, struct request_header *);
extern char *argument(int);
extern void putchar(int);
extern void puts(char *);