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还是一个词法分析程序

               1        Inheritance flag, File private to      3.0
                        current process
    ---------------------------------------------------------------
    StringSeg - Segment address of ASCIIZ file spec.
    StringOfs - Offset within StringSeg of file spec.
Output
    If function successful:
        Carry flag - clear
        ax - file handle
    If function failed
        Carry flag - set
        ax - error code:
            1 - Function number invalid
            2 - File not found
            3 - Path not found or file doesn't exist
            4 - No handle available
            5 - Access denied
          OCH - File access code invalid
Registers modified: ax, dx, ds, Flags
Syntax: OpenFile  AccessMode, StringSeg, StringOfs

CloseFile
---------
Function: Closes a file associated with a file handle.
DOS Function: 3Eh
DOS Versions: 2, 3
Input
    Handle - File handle of file to close
Output
    If function successful:
        Carry flag - clear
    If function failed:
        Carry flag - set
        ax - error code:
            6 - handle invalid or not open
Registers modified: ax, bx, Flags
Syntax: CloseFile   Handle

ReadFile
--------
Function: Reads Count bytes from the file referenced by the file handle.
DOS Function: 3Fh
DOS Versions: 2, 3
Input
    Handle - DOS file handle of file to read from
    Count - # of bytes to read
    StringSeg - Segment address of buffer to store data in
    StringOfs - offset within StringSeg of storage buffer
Output
    If function successful:
        Carry flag - clear
        ax - # of bytes read(0 if EOF)
    If function failed
        Carry flag - set
        ax - error code:
            5 - Access denied
            6 - Invalid handle or file not open
Registers modified: ax, bx, cx, ds, Flags
Syntax: ReadFile    Handle, Count, StringSeg, StringOfs

WriteFile
---------
Function: Writes Count bytes to the file referenced by the file handle.
DOS Function: 40h
DOS Versions: 2, 3
Input
    Handle - DOS file handle of file to write to
    Count - # of bytes to write
    StringSeg - Segment address of buffer storing data
    StringOfs - offset within StringSeg of storage buffer
Output
    If function successful:
        Carry flag - clear
        ax - # of bytes read(0 if disk full)
    If function failed
        Carry flag - set
        ax - error code:
            5 - Access denied
            6 - Invalid handle or file not open
Registers modified: ax, bx, cx, ds, Flags
Syntax: WriteFile    Handle, Count, StringSeg, StringOfs

DeleteFile
----------
Function: Deletes the file pointed to by StringSeg:StringOfs.
DOS Function: 41h
DOS Versions: 2, 3
Input
    StringSeg - segment address of the filename
    StringOfs - offset from StringSeg of the filename
Output
    If function successful:
        Carry flag - clear
    If function failed
        Carry flag - set
        ax - error code:
            2 - File not found
            5 - Access denied
Registers modified: ax, dx, ds, Flags
Syntax: DeleteFile  StringSeg, StringOfs

MoveFilePtr
-----------
Function: Positions the file pointer in the file referenced by Handle.
DOS Function: 42h
DOS Versions: 2, 3
Input
    Mode - Offset method as defined below
    MODE    FUNCTION
    ----    -----------------------------------------------------------
      0     absolute byte offset from beginning of file(always unsigned
            long integer)
      1     byte offset from current location(signed long integer)
      2     byte offset from end of file(signed long integer)
    -------------------------------------------------------------------
    Handle - File handle
    OffsetHigh - Most significant word of offset
    OffsetLow  - Least significant word of offset
Output
    If function successful:
        Carry flag - clear
        dx - most significant word of new pointer
        ax - least significant word of new pointer
    If function failed
        Carry flag - set
        ax - error code:
            1 - Function number invalid
            6 - Handle invalid or not open
Registers modified: ax, bx, cx, dx, Flags
Syntax: MoveFilePtr Mode, Handle, OffsetHigh, OffsetLow

GetSetAttributes
----------------
Function: Gets or sets the file attributes.
DOS Function: 43h
DOS Versions: 2, 3
Input
    Mode
        0 - Get file attributes
        1 - Set file attributes
    Attributes - New attributes or location to store file's current
                 attributes.
    StringSeg - Segment address of the filename to check/modify
    StringOfs - Offset within StringSeg of the filename
Output
    If function successful:
        Carry flag - clear
        If al = 0 on call
            cx - attribute
    If function failed:
        Carry flag - set
        ax - error code:
            1 - Function code invalid
            2 - File not found
            3 - Path not found or file doesn't exist
            5 - Attribute can't be changed
Registers modified: ax, cx, dx, ds, Flags
Syntax: GetSetAttributes    Mode, Attributes, StringSeg, StringOfs

IOCTL
-----
Function: Passes control information to a device driver. Note that you must
          provide either the buffer address parameters or the device
          information parameter but not both.
DOS Function: 44h
DOS Versions: 2, 3
Input
    Function - What to do as defined below:
    FUNCTION    RESULT
    -----------------------------------------------------------------------
        00h     Get device information
        01h     Set device information
        02h     Read from character device control channel to a buffer
        03h     Write to a character device control channel from a buffer
        04h     Read from block device control channel to a buffer
        05h     Write to a block device control channel from a buffer
        06h     Get the input status
        07h     Get output status
        08h     Check whether a block device is changable(DOS 3.0)
        09h     Check whether a drive is local or remote(DOS 3.1 &
                Microsoft Networks)
        0Ah     Check whether a handle is local or remote(DOS 3.1 &
                Microsoft Networks)
        0Bh     Change the sharing retry count
    -----------------------------------------------------------------------
    HandleDrive - Handle(functions 0, 1, 2, 3, 6, 7, 0Ah)
                - Drive(0 = default, 1 = A, etc.)
    Count - # of bytes to read/write
    BufSegDevInfo - Represents Segment address of the input/output
                    buffer(functions 2-5)
                  - Represents device information(function 1).
    BufferOfs - offset of the storage buffer(functions 2-5)
Output
    Carry flag = clear  - operation successful
        ax - # of bytes read/written(functions 2-5)
        al - 0 = not ready(functions 6-7)
           - 1 = ready
        ax - 0 = removable(function 8)
           - 1 = fixed
        dx - Device information(function 0)
    Carry flag = set
        ax - error code
           1 = Invalid function number
           4 = No handle available
           5 = Access denied
           6 = Invalid handle or device not open
         0Dh = Invalid data
         0Fh = Invalid drive number
Registers modified: ax, bx, cx, dx, ds, flags
Syntax: IOCTL   Function, HandleDrive, Count, BufSegDevInfo, BufferOfs

DuplicateHandle
---------------
Function: Duplicates a file handle that is associated with an open file or
          device.
DOS Function: 45h
DOS Versions: 2, 3
Input
    Handle - the handle to duplicate
Output
    carry flag = clear
        ax - new file handle
    carry flag = set
        ax - error code
           4 = No more file handles available
           6 = Invalid handle or file not open
Registers modified: ax, bx, flags
Syntax: DuplicateHandle Handle

ForceDupHandle
--------------
Function: Takes two file handles and makes the second one equal to the first.
DOS Function: 46h
DOS Versions: 2, 3
Input
    Original - Original file handle
    Copy     - Copy of the file handle
Output
    carry flag = clear - operation successful
    carry flag = set
        ax - error code
           4 = No more file handles available
           6 = Invalid handle or file not open
Registers modified: ax, bx, cx, flags
Syntax: ForceDupHandle  OriginalHandle, HandleCopy

GetCurrentDir
-------------
Function: Returns the current DOS directory on the indicated disk drive.
DOS Function: 47h
DOS Versions: 2, 3
Input
    Drive - Disk drive(0 = default, 1 = A, etc.)
    StringSeg - Segment address of 64-byte buffer to store directory
                name in
    StringOfs - Offset within StringSeg of the 64-byte buffer
Output
    If function successful:
        Carry flag - clear
        The buffer is filled with the full path
    If function failed
        Carry flag - set
        ax - error code:
          0Fh - Invalid drive specification
Registers modified: ax, dl, si, ds, Flags
Syntax: GetCurrentDir   Drive, StringSeg, StringOfs

AllocateMemory
--------------
Function: Allocates Paragraphs paragraphs of memory.
DOS Function: 48h
DOS Versions: 2, 3
Input
    Paragraphs - # of paragraphs to allocate
Output
    If function successful:
        Carry flag - clear
        ax - initial segment of allocated block
    If function failed:
        Carry flag - set
        ax - error code:
            7 - If memory control blocks destroyed
            8 - If insufficient memory
        bx - size of largest block available
Registers modified: ax, bx, Flags
Syntax: AllocateMemory  Paragraphs

FreeMemory
----------
Function: Frees a DOS memory block.
DOS Function: 49h
DOS Versions: 2, 3
Input
    BlockAddress - segment address of the memory block
Output
    If function successful:
        Carry flag - clear
    If function failed:
        Carry flag - set
        ax - error code:
            7 - If memory control blocks destroyed
            8 - If insufficient memory
        bx - size of largest block available
Registers modified: ax, es, Flags
Syntax: FreeMemory  BlockAddress

ModifyMemory
------------
Function: Modifies A DOS memory blocks size.
DOS Function: 4Ah
DOS Versions: 2, 3
Input
    Size - New block size in paragraphs
    MemoryBlock - Segment address of current DOS memory block
Output
    If function successful:
        Carry flag - clear
    If function failed
        Carry flag - set
        ax - error code:
            7 - Memory control blocks destroyed
            8 - Insufficient memory
            9 - Incorrect segment in es
        bx - maximum block size available
Registers modified: ax, bx, es, Flags
Syntax: ModifyMemory    Size, MemoryBlock

Exec
----
Function: Runs another program or loads an overlay into memory.
DOS Function: 4Bh
DOS Versions: 2, 3
InputSyntax
    Type - Indicates if the macro is running an application or loading an
           overlay
    ParmSeg - Segment address of parameter block
    ParmOfs - Offset of parameter block
    ProgramSeg - Segment address of program specification
    ProgramOfs - Offset of program specification
Output
    carry flag = clear - operation successful
        all registers except cs and ip are destroyed
    carry flag = set - operation not successful
        ax - error code
           1 = Invalid function
           2 = Program not found
           5 = Access denied
           8 = Insufficient memory to run the program
         0Ah = Invalid environment
         0Bh = Invalid format
Registers modified: ax, bx, cx, dx, si, di, bp, sp, es, ds, ss, flags
Syntax: Exec    Type, ParmSeg, ParmOfs, ProgramSeg, ProgramOfs

TerminateProgram
----------------
Function: Terminates the program. If running on DOS 1.0 or 1.1, use
          Terminate10Program.
DOS Function: 4Ch
DOS Versions: 2, 3
Input
    ErrorLevel - ErrorLevel to return to DOS
Output
    None
Register modified
    NA
Syntax
    TerminateProgram    ErrorLevel

GetReturnCode
-------------
Function: Gets the return code after an Exec.
DOS Function: 4Dh
DOS Versions: 2, 3
Input
    none
Output
    ah  - exit type
        0 = normal program termination
        1 = program was terminated by a CTRL-C
        2 = A critical device error terminated the program
        3 = Function 31h terminated the program
    al - return code of child process
Registers modified: ax, flags
Syntax: GetReturnCode

FindFirst
---------
Function: Finds the first entry in a directory that matches the given file
          specification. The information about the file is then stored in the
          current DTA.
DOS Function: 4Eh
DOS Services: 2, 3
Input
    Attributes - Attributes to use in search for file
    StringSeg - segment address of the filename
    StringOfs - offset from StringSeg of the filename
Output
    If function successful:
        Carry flag - clear
        DTA is initialized with file information
    If function failed
        Carry flag - set
        ax - error code:
            2 - Invalid path
          12h - No matching entry found
Registers modified: ax, cx, dx, ds, Flags
Syntax: FindFirst   Attributes, StringSeg, StringOfs

FindNext
-------
Function: Finds the next entry in a directory that matches the file
          specification last given to FindNext. The information about the file
          is then stored in the current DTA.
DOS Function: 4Fh
DOS Services: 2, 3
Input
    none