core.h

是一个手机功能的模拟程序

/******************************************************************************
 * Flash File System (ffs)
 * Idea, design and coding by Mads Meisner-Jensen, [e-mail]
 *
 * ffs core functions
 *
 * $Id: core.h,v 1.1.1.1 2004/06/19 06:00:30 root Exp $
 *
 ******************************************************************************/
#include "rv_defined_swe.h"


/******************************************************************************
 * Compile option switches
 ******************************************************************************/

// FFS compiled with extra test functionality
#define FFS_TEST 1

// Default size of working buffer used by stream i/o functions
#define FFS_FD_BUF_SIZE 8192

// Default max number of simultaneous open files
#ifdef RVM_MSFE_SWE
#define FFS_FD_MAX 20
#else
#define FFS_FD_MAX 4
#endif

#define FFS_RECLAIM_NEW 1

/******************************************************************************
 * Compile constants
 ******************************************************************************/

// FFS API version (in four-digit BCD format)
#define FFS_API_VERSION ((uint16) 0x0641)

// FFS_DRV_VERSION is in drv.h

// TMFFS protocol version is in tmffs.h

// Magic for determining (formatted) file system version. First two digits
// represent major version, bottom two digits represent minor version. An
// ffs code compiled for one major version X is compatible with any other
// format version with major = X. Minor version is incremented when adding
// new features that does not break compatibility.
#define FFS_FORMAT_VERSION (0x0210)
#define BLOCK_MAGIC_LOW    ('f'<<8|'F') // "Ffs#"
#define BLOCK_MAGIC_HIGH   ('#'<<8|'s')
#define BLOCK_MAGIC        ((BLOCK_MAGIC_HIGH << 8)|(BLOCK_MAGIC_LOW))

// Absolute maximum number of inodes allowed
#define FFS_INODES_MAX 2048

// Default maximum number of inodes allowed
#define FFS_INODES_MAX_DEFAULT 1024

// Default number of path components (limit due to recursiveness of
// inodes_reclaim())
#define FFS_PATH_DEPTH_MAX 6

// Maximum number of blocks (flash sectors) in a ffs system. FFS_BLOCKS_MAX
// must be >= the number of blocks in the largest flash device memory
// map. It is used to allocate the number of entries in the static bstat
// array.
#define FFS_BLOCKS_MAX 128
// Default size of journal file (represented as 256'ths of the blocksize)
#define FFS_JOURNAL_SIZE_IN256THS 16  // one 16'ths of the block size. 

// Without the min size will the maximum of files (fs.blocks_files_max) in
// one block be 32 files if the blocksize is 8kB!
#define FFS_JOURNAL_SIZE_MIN 1024

#define FFS_JOURNAL_NAME ".journal"

// Default max size of file name (excluding null terminator)
#define FFS_FILENAME_MAX 20

// Maximum distance in age between youngest and oldest blocks
#define FFS_DAGE_MAX 256
#define FFS_DAGE_GAIN_MIN (FFS_DAGE_MAX / 4)
#define FFS_DAGE_EARLY_WIDTH 64

// Offset on file descriptors 
#define FFS_FD_OFFSET '1'

// Macros to set flags and test bits in flash memory words (negative logic)
#define BIT_SET(value, bits) ((value) & (~bits))
#define IS_BIT_SET(value, bits) (~(value) & (bits))

// Number of free inodes and journal entries to keep for "emergencies"
#define FFS_INODES_MARGIN  4
#define FFS_JOURNAL_MARGIN 4


/******************************************************************************
 * Macros used in both drv.c and core.c
 ******************************************************************************/

// Convert a offset_t value to a block index
#define offset2block(offset) (((uint32) offset) >> dev.binfo[0].size_ld)
 
// Convert between offset and address
#define offset2addr(offset) (dev.base + (offset))

// Size of a block
#define blocksize(block) (1 << dev.binfo[block].size_ld)

// Test if flag is set
#define is_open_option(options, flags) ((options & flags) == flags)

// Amount of reserved space. 
#define	RESERVED_LOW  2 * fs.journal_size 
#define RESERVED_NONE 0

// We have to saturate because a recently reclaimed inodes block could
// theoretically possess a high age
#define saturate_dage(dage) (dage > (2*FFS_DAGE_MAX) ? (2*FFS_DAGE_MAX) : dage) 

/******************************************************************************
 * External declarations
 ******************************************************************************/

extern struct fs_s fs;
extern struct block_stat_s bstat[FFS_BLOCKS_MAX];

extern struct ffs_stats_s stats;

extern const struct block_info_s *binfo;


/******************************************************************************
 * Block Types
 ******************************************************************************/

// Block age, ie. number of times block has been erased
typedef uint16 age_t;

// Maximum age a block can have
#define BLOCK_AGE_MAX 0xFFFF

// ffs block status flags. These are stored in the first 2 bytes of
// the ffs block in the flash sector.
enum BLOCK_FLAGS {
    BF_LOST        =  0x80,  // block is lost and will soon be erased
    BF_FREE        =  0x40,  // free (preformatted and with block magic)
    BF_DATA        =  0x02,  // data
    BF_CLEANING    =  0x01,  // block is being cleaned
    BF_INODES      =  0x10,  // block contains inodes
    BF_COPYING     =  0x04   // block is a coming inodes block
};
enum BLOCK_STATES {
    BF_IS_EMPTY       = ~(0),
    BF_IS_FREE        = ~(BF_FREE),
    BF_IS_DATA        = ~(BF_FREE | BF_DATA),
    BF_IS_CLEANING    = ~(BF_FREE | BF_DATA | BF_CLEANING),
    BF_IS_COPYING     = ~(BF_FREE | BF_COPYING),
    BF_IS_INODES      = ~(BF_FREE | BF_COPYING | BF_INODES),
    BF_IS_INODES_LOST = ~(BF_FREE | BF_COPYING | BF_INODES | BF_LOST)
};

// Header of each FFS block
struct block_header_s {
    uint16 magic_low;  // 32-bit magic number
    uint16 magic_high;
    uint16 version;    // FFS_FORMAT_VERSION used for formatting
    age_t  age;        // number of times this block has been erased
    uint16 flags;      // status flags of this block (BLOCK_FLAGS)
    uint16 reserved0;
    uint16 reserved1;
    uint16 reserved2;
};

// Important the below define MUST fit to the size of the header that is written
#define BHEADER_SIZE sizeof(struct block_header_s)

#define OLD_BLOCK_MAGIC_LOW    ('S'<<8|'F') // "FS"
#define OLD_FFS_FORMAT_VERSION (0x0100)     // 1.00 (in four-digit BCD format)

// Old header of each FFS block. From old/previous FFS format version
struct block_header_old_s {
    uint8  flags;
    uint8  copied;
    uint8  magicflags;
    uint8  reserved0;
    uint16 magic_low;
    uint16 magic_high;
    uint16 reserved1;
    uint16 reserved2;
};

// Block status. This struct holds the status of one ffs block This relation
// is always valid: <block size> = <used> + <lost> + <free>. The block size
// is obtained from the corresponding block_info structure. <used> and
// <lost> variables always holds a value which is a multiple of
// FFS_GRANULARITY.  For inodes, <used> is number of inodes in active use,
// <lost> is number of deleted/lost inodes, <numfiles> is the index of the
// first free inode.
struct block_stat_s {
    blocksize_t used;    // number of used bytes
    blocksize_t lost;    // number of lost bytes
    uint16      flags;   // flash block flags (first 16 bits of each block)
    uint16      objects; // number of valid objects
};


/******************************************************************************
 * Object Types
 ******************************************************************************/

// This enum MUST be in sync with the one in ffs.h.
enum OBJECT_TYPE_E {
    // remaining filetypes are in ffs.h
    OT_ERASED  = 0,
    OT_NULL    = 7,
    OT_MASK    = 7,
    OT_MAX     = 4
};

// This enum MUST be in sync with the one in ffs.h.
enum OBJECT_FLAGS_E {
    // remaining object flags are in ffs.h
    OF_UNDEF0   = 1<<5,
    OF_UNDEF1   = 1<<6,
    OF_EXACT    = 1<<7, // used by control()/update_commit() interaction. This
                        // is *not* an object flag!
    OF_ALL      = OF_READONLY, // all flags allowed to be changed by user
    OF_MASK     = 0xF0
};

struct inode_s {
    uint16      size;
    uint8       reserved;  // size extension?
    objflags_t  flags;
    iref_t      child;     // link to first inode in dir (this inode is a dir)
    iref_t      sibling;   // link to next inode in same directory
    location_t  location;  // location of object
    uint16      sequence;  // 
    uint16      updates;   // times this object has been updated
};

struct file_descriptor_s {      
    char    *buf;          // Write buffer 
    iref_t  seghead;       // First chunk. Contain file name and optional data 
    iref_t  wch;           // Inode of work chunk (if chunk is read to buf)
    int     fp;            // File pointer
    int     wfp;           // Work file pointer always points to start of wch
    int     size;          // Size of object (all chunks and data from buf)
    int8    options;       // Open options
    int     dirty;         // Indicate if buf contain valid data or not
};


/******************************************************************************
 * Journal types and global fs structure
 ******************************************************************************/

enum JOURNAL_FLAGS {
    JOURNAL_WRITING = 0x02,  // journal is being written to journal file
    JOURNAL_READY   = 0x04,  // journal has been written to journal file
    JOURNAL_DONE    = 0x08   // journal has been written to ffs
};

enum JOURNAL_STATES {
    JOURNAL_IS_EMPTY   = ~(0),
    JOURNAL_IS_WRITING = ~(JOURNAL_WRITING),
    JOURNAL_IS_READY   = ~(JOURNAL_WRITING | JOURNAL_READY),
    JOURNAL_IS_DONE    = ~(JOURNAL_WRITING | JOURNAL_READY | JOURNAL_DONE)
};

// Journal entry structure. Note that the state byte *MUST* be the first
// byte of the structure!
struct journal_s {
    uint8      state;    // state of journal entry.
    objflags_t flags;    // type of object
    iref_t     i;        // iref of object
    iref_t     diri;     // iref of object that is this object's parent/sibling
    iref_t     oldi;     // iref of object being replaced (only for updates)
    location_t location; // object's location
    uint16     size;     // object's size
    iref_t     repli;    // inode which is replaced
};

// Main ffs info struct (initialised by ffs_initialize())
struct fs_s {
    struct inode_s *inodes_addr; // base address of inodes
    iref_t    root;            // iref of root directory
    bref_t    inodes;          // index into bstat containing inode block
    bref_t    newinodes;       // index into bstat containing new inode block
    bref_t    blocks_free_min; // Number of spare blocks (0 or 1)
    int       filesize_max;    // Max size of object data
    int       reserved_space;  // Byte size of space reserved for journal relocation
    iref_t    inodes_max;      // Max number of inodes possible
    iref_t    inodes_high;     // number of inodes triggering an inodes_reclaim()
    iref_t    objects_max;     // Max number of objects (valid inodes) allowed