disk8: Initial commit

[pdp8.git] / sw / disk8 / src / structures.h

/* Data structures used in disk8 */

#ifndef D8_STRUCTURES_H
#define D8_STRUCTURES_H

/* Our basic data type representing one 12 bit word */
typedef unsigned short int p8word;

/*
 * This represents one 256 word block system memory or file system block.
 * Contents can be accessed by the diskblocks[] member as well.
 */
typedef union {
  p8word data [0400];      
} os8_block_t;


typedef struct {
  p8word data[4];
} os8_file_name_t;


typedef union {
  p8word data[5];
  struct{
    struct{
      unsigned int device_number :4;
      unsigned int file_size : 8;  /* In system blocks */
      unsigned int dummy: 4;
    };
    os8_file_name_t file_name;
  };  
} what_was_that_t;


typedef struct {
  /* Minus the number of entries in this segment (block) */
  p8word neg_entries;  

  /* Starting block number of first file in this segment */
  p8word first_file_start; 

  /* Link to next segment, 0 if no next segment */
  p8word next_segment;    
  
  /* Flag word */
  p8word flag_word;

  /* Minus the number of additional Information words */
  p8word additional_info_neg;
  
  /* The directory data */
  p8word entry_data[0400-06];

  /* End of directory word */
  p8word end_of_dir;

} os8_directory_segment_t;


/*!
 *\brief OS/8 partition header
 *
 * This is the major structure of a device heading.
 * Normal volumes can start the data at block 007,
 * system volumes mustn't touch blocks 007-067.
 */
typedef struct {
  /* 000     */ os8_block_t           bootblock;
  /* 001-006 */ os8_directory_segment_t  directory[6];
  /* 007-012 */ os8_block_t           keyboard_monitor[4];
  /* 013-015 */ os8_block_t           usr[3];
  /* 016-025 */ os8_block_t           device_handlers[8];
  /* 026     */ os8_block_t           enter_processor;
  /* 027-050 */ os8_block_t           system_scratch[18];
  /* 051-053 */ os8_block_t           command_decoder[3];
  /* 054-055 */ os8_block_t           save_and_date_ovl[2];
  /* 056     */ os8_block_t           mon_errors;
  /* 057     */ os8_block_t           chain_processor;
  /* 060-063 */ os8_block_t           system_odt[4];
  /* 064     */ os8_block_t           reserved_for_expansion;
  /* 065     */ os8_block_t           ccl_reminiscences;
  /* 066     */ os8_block_t           td8e_resident_code;
  /* 067     */ os8_block_t           ccl_overlay;
} os8_partition_header_t;


/********************************************************************************
 * Following are "private" structures not directly related to OS/8.
 */


typedef union{
	os8_partition_header_t header;
	os8_block_t data[4096];
} os8_partition_t;

typedef enum {IT_UNKNOWN=0, IT_DISK, IT_DECTAPE} image_type_t;


/*
 * File system type
 * System is for boot images, beginning of data at block 070.
 */
#define FST_NORMAL 0
#define FST_SYSTEM 1


/*!
 *\brief Memory representation of a disk or tape image
 *
 * This structure contains all working info and data
 * associated with a disk or DECTape image.
 * The image itself \e can contain at most two complete
 * filesystems as RK05 disks are split into two partitions.
 */
typedef struct {
  
  //! Size of the image in blocks
  unsigned int size;     
  
  //! Raw byte size of the imported file
  unsigned int raw_size; 
  
  //! Type of the image, perhaps used later
  image_type_t type; 
  
  union {
    //! All blocks in the image
    os8_block_t data[2*4096]; 
    struct {
      //! The first (and - on tape - only) partition
      os8_partition_t part0; 
      //! The second partition of a disk
      os8_partition_t part1; 
    };
  };
} image_t;


/*
 * OS/8 file types
 * 
 * Tentative files should not occur at the moment!
 */
typedef enum{
  FT_EMPTY=0,   //!< A \e unused file 
  FT_PERMANENT, //!< A normal fixed file
  FT_TENTATIVE  //!< A Open file (for writing)
} os8_filetype_t;

/* Maximal number of additional information words in a directory entry */
#define MAX_ADDITIONAL_INFO 0200

typedef struct os8_dir_entry_s os8_direntry_t;

struct os8_dir_entry_s  {
  os8_filetype_t type;  //!< Filetype
  char name[10];        //!< ASCII file name, not used on empty files
  int  size_blocks;     //!< Size of the file in blocks
  int start_block;      //!< First block of the file
  os8_direntry_t *next; //!< Pointer to next entry
  os8_direntry_t *prev; //!< Pointer to previous entry
  p8word additional_info[MAX_ADDITIONAL_INFO];
};



typedef struct {
  os8_direntry_t* entries; //!< Linked list of entries in this directory
  int additional_info;  //!< Size of additional info in each entry
} directory_t;


#endif