iwhereis.asm

还是一个词法分析程序

;   FILENAME: IWHEREIS.ASM
;
;   Copyright (c) 1988, 1992 by Borland International, Inc.
;
;   DESCRIPTION:  This program does a search for the file(s) specified on the
;   command line. It can also perform a DOS command on each file that is
;   found.
;
; Syntax: WHEREIS [d:][path]filename filename filename... [dos_command]
;  dos_command is a command surrounded by "",'', or []. It will be called
;  for each file that is found. It should include at least one of these:
;     %1 - Insert full path, filename and extension
;     %2 - Filename and extension (no path)
;     %3 - Only the path.
;     %4 - Only the filename before the extension followed by a .
;     %5 - Only the extension, preceeded by a .
;  For example to delete all .BAK files on a drive:
;     WHEREIS  *.BAK [DEL %2]",13,10>
;
;   Note that dos_command may be any valid DOS command, including invoking
;   batch files or built-in DOS commands. Note that the RMDIR, (also RD),
;   command should not be used on the directory that WHEREIS is currently
;   executing in.
;
;
;   ASSEMBLY INSTRUCTIONS: To assemble this module use the following
;   TASM command line.
;
;       TASM /m /dMDL=memorymodel iwhereis
;
;   /m in the above command line allows TASM to use extra passes to resolve
;   jumps and other operations to their shortest form and get rid of extra NOPs.
;   'memorymodel' in the above command line may be replaced by TINY, SMALL,
;   MEDIUM, COMPACT, LARGE or HUGE. If assembling this module to run on
;   a 286/386 machine, turn on the P286 directive in order to take advantage of
;   286/386 specific instructions. For example:
;
;       TASM /m /dMDL=memorymodel /jP286 iwhereis
;
;   SYSTEM REQUIREMENTS:
;       TASM 2.0
;       256K
;       DOS 2.0 or later

; TURBO ASSEMBLER NEW FEATURES:
; TASM 2.0 has many new features. The following is a list of a few of
; them that have been used to make this program easier and more readable.
; To find the examples in the code, just seach for "**n", where n is a
; number from the following table.

; Special TASM 2.0 features:
;    **1  - TASM automatically pushes the immediate value in a way that
;           preserves all registers if the processor mode is 8086. If
;           186 or above, then TASM pushes the value directly.
;    **2  - Many lines of assembler are replaced by the use of the
;           extended call syntax.
;    **3  - Conditional jumps that go out of range are automatically
;           adjusted to a different code sequence that allows the
;           further jump. Other jumps, even if forward referenced, are
;           automatically changed to the shortest possible code sequence
;           without extra NOPs, because of multipass capability.
;    **4  - TASM handles forward referenced variables that occur
;           in a segment other than DS: by automatically inserting
;           the proper segment override, and without causing phase errors.
;    **5  - TASM's ability to handle multiple objects on a single
;           PUSH or POP command makes coding shorter.
;    **6  - TASM's new line continuation feature while in IDEAL mode
;           makes long argument lists very easy.


jumps      ; Have TASM automatically resolve out of range jumps

%tabsize 4

ifndef  MDL
    display "Error: This module requires that you provide a memory model"
    display "    definition on the command line. I.E. /dMDL=SMALL."
    err ; Force a fatal error
else

    ideal                   ; Use TASM's Ideal mode
%   model   MDL,pascal      ; Define the memory model
                            ; Set language to PASCAL so we can rely on TASM's
                            ; new extended call features.

    ProgramVersion EQU "2.01"

    include "iwhglobl.inc"  ; Public symbol declarations
    include "imacros.mac"   ; Various macros
    include "bios.inc"
    include "ibios.mac"
    include "kbd.inc"      ; Keyboard scan codes
    include "dos.inc"      ; Equates representing DOS functions/services
    include "idos.mac"

    stack   7FFFh           ; Allocate 32K stack




    codeseg
    SavedDS     dw  ?       ; For the control-break handler to find the path
                            ; variables for restoring the original path and
                            ; drive.

    BreakPressed    db 0    ; Set by Int1B handler to one if
                            ; CTRL-BREAK pressed. Allows us to break even
                            ; if DOS BREAK is set to off.
    global BreakPressed:byte     ; So other modules can check it!


    dataseg

    PspAddress  dw  ?       ; Segment address of Program Segment Prefix(PSP)
    DisplayPage db  0       ; Current display page

    Old1BHandlerSeg dw ?
    Old1BHandlerOfs dw ?


    include "WHUSAGE.INC"   ; Usage screen declaration

    ; Pascal style strings to store the parsed file specification.

    Drive       db  0," :  "
    Path        db  MAX_PATH_LENGTH  dup (0)

    ; Following is used as a scratchpad when parsing additional filespecs
    ; from the command line.
    tempDrive   db  0," :  "
    tempPath    db  MAX_PATH_LENGTH  dup (0)


    FileSpecCounter db 0    ; Count how many filespecs we parsed
    NextFileSpec    dw 0    ; Location of where to put next filespec

    DrivePtr    dw   ?      ; Points to where the file parse routine should
    PathPtr     dw   ?      ; place its results.


    FileSpec    db  MAX_FILE_SPECS dup (FILE_SPEC_SIZE dup (0))
                            ; Make room for the filenames, each with a
                            ; preceeding length byte and terminating 0

    db  '\'
    HomeDirectory   db  MAX_PATH_LENGTH dup (0)
    OldDrive        db  ?

    ; When working through the arguments on the command line to setup
    ; filespecs,
    CurrentArgument db  MAX_PATH_LENGTH+FILE_SPEC_SIZE dup (0)

    codeseg

    proc    GetArgument
    ;   This procedure gets an argument transfered into a temporary
    ;   buffer where all leading spaces are removed from the string.
    ;
    ;   Input
    ;       AL contains number of argument to get.
    ;   Output
    ;       If argument exists:
    ;          AL number of argument
    ;          ES:DI points to temporary argument buffer
    ;       If argument does not exist:
    ;          AL contains 0
    ;   Calling conventions
    ;       NA
    ;   Registers modified
    ;       all

        call    ParamString
        or      al,al
        jz      @@Finished      ; A zero return means no more arguments.



        push    ax              ; Save it to restore return value from ParamString

; **2
;   The following lines are neatly replaced by a single line CALL with
;   extended syntax. All the variables are automatically pushed on the
;   stack in the proper order, automatically.
;
;        push    es
;        push    di
;
;        if (@Cpu and 100b) eq 100b
;            push    seg CurrentArgument
;        else
;            mov     ax, seg CurrentArgument
;            push    ax
;        endif
;        if (@Cpu and 100b) eq 100b
;            push    offset CurrentArgument
;        else
;            mov     ax, offset CurrentArgument
;            push    ax
;        endif

        xor     ah,ah
        mov     al,[byte es:di]
        inc     ax

        call    ByteCopy,es,di,seg CurrentArgument,Offset CurrentArgument

    @@DeleteSpaces:
        cmp     [CurrentArgument+1], SPACE
        jne     @@NoMoreSpaces

; **2
;        if (@Cpu and 100b) eq 100b
;            push    seg CurrentArgument
;        else
;            mov     ax, seg CurrentArgument
;            push    ax
;        endif
;        if (@Cpu and 100b) eq 100b
;            push    offset CurrentArgument
;        else
;            mov     ax, offset CurrentArgument
;            push    ax
;        endif

        mov     cx, 1           ; Remove the first character
        mov     ax, 1           ; from the string
        call    DeleteChar,seg CurrentArgument,offset CurrentArgument

        jmp     @@DeleteSpaces
    @@NoMoreSpaces:
        mov     ax,seg CurrentArgument
        mov     es,ax
        mov     di,offset CurrentArgument

        pop     ax



    @@Finished:
        ret
    endp    GetArgument



    dataseg

MakePascalString  SearchMssg,<"WHEREIS parameters:",13,10>

    codeseg
    proc    Show_Args
    ;   This procedure displays all the command line parameters sent
    ;   to the program.
    ;
    ;   Input
    ;       none
    ;   Output
    ;       none
    ;   Calling conventions
    ;       NA
    ;   Registers modified
    ;       all

        push es di ax                 ;**5
        call WritePascalString,ds,offset SearchMssg
        mov  [argcount],1             ;**4

    @@Show_loop:
        mov  al,[argcount]
        call GetArgument
        or   al,al         ; Check for zero return. Means no more arguments.
        jz   @@Show_Exit

        call WritePascalString,es,di  ; Show the current argument

        push seg BlankLine            ;**1
        push offset BlankLine
        call WritePascalString

        inc  [argcount]               ;**4
        jmp  @@Show_loop

    @@Show_Exit:
        pop  ax di es                 ;**5
        ret

    argcount db 1                     ;**4
    endp    Show_Args



    proc Main

    ;************************* Program Entry Point ***************************
    ; Execution of the program begins here.

    EntryPoint:
        mov     ax, @data       ; Initialize ds by moving segment address
        mov     ds, ax          ; of data segment into ds register
        push    bp              ; Setup a starting stack frame.
        mov     bp, sp

        call    Initialize      ; Initialize data structures, etc.

        call    Show_Args


        mov     [FileSpecCounter],0  ; FileSpecCounter has # files found so far