#ifndef __DISK_H__
#define __DISK_H__

/* 
 * disk.h
 *       This module simulates a SCSI harddrive
 */

/* get the correct version of Windows NT recognized */
#define _WIN32_WINNT 0x0400
#include <windows.h>
#include <stdio.h>

#include "defs.h"
#include "interrupts.h"

#define DISK_INTERRUPT_TYPE 4

#define DISK_BLOCK_SIZE 4096
#define MAX_PENDING_DISK_REQUESTS 128

/* global variables that control the behavior of the disk */
extern double crash_rate;
extern double failure_rate;
extern double reordering_rate;

typedef enum {
  DISK_READWRITE=0,
  DISK_READONLY=1
} disk_flags_t;
 
typedef struct {
  int size;    /* in blocks */
  int flags;
} disk_layout_t;

typedef enum { DISK_RESET, /* required after disk crash */
	       DISK_SHUTDOWN,
	       DISK_READ,
	       DISK_WRITE } disk_request_type_t ;

typedef enum { DISK_REPLY_OK,
	       DISK_REPLY_FAILED, /* disk failed on this request for no apparent reason */
	       DISK_REPLY_ERROR, /* disk nonexistent or block outside disk requested */ 
	       DISK_REPLY_CRASHED } disk_reply_t;

/* 
 * Datastructure used to make and receive replies to disk
 * requests.
*/

typedef struct {
  int blocknum;
  char* buffer; /* pointer to the memory buffer */
  disk_request_type_t type; /* type of disk request */
} disk_request_t; 

typedef struct disk_queue_elem_t {
  disk_request_t request;
  struct disk_queue_elem_t* next;
} disk_queue_elem_t ;

/* Do not modify by hand elements of type disk_t since sincronization
   is required
*/

typedef struct {
  disk_layout_t layout;
  FILE* file;
  disk_queue_elem_t* queue;
  disk_queue_elem_t* last;
  HANDLE semaphore; /* the semaphore should be signaled when something is added to the queue */
} disk_t;

/* structure used to pass arguments through interrupts */
typedef struct {
  disk_t* disk;
  disk_request_t request;
  disk_reply_t reply;
} disk_interrupt_arg_t;


typedef void (*disk_handler_t)(disk_t* disk, disk_request_t, disk_reply_t);

int 
disk_send_request(disk_t*, int, char*,disk_request_type_t);

int
disk_create(disk_t* disk, char* name, int size, int flags);

int
disk_startup(disk_t* disk, char* name);

int
disk_shutdown(disk_t* disk);

void
disk_set_flags(disk_t* disk, int flags);

void
disk_unset_flags(disk_t* disk, int flags);

int
disk_read_block(disk_t* disk, int blocknum, char* buffer);

int
disk_write_block(disk_t* disk, int blocknum, char* buffer);

void
install_disk_handler(interrupt_handler_t disk_handler);

#endif