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;* OpenFile - Opens specified file for reading or writing. See the CopyFile
;* procedure for another example of using DOS Function 3Dh to open files.
;*
;* Shows:   DOS Function - 3Dh (Open File)
;*
;* Params:  access - Access code:  0 = read    1 = write    2 = read/write
;*          fspec - Pointer to ASCIIZ file specification
;*
;* Return:  Short integer with file handle or -1 for error
 
OpenFile PROC \
        USES ds, \
        access:WORD, fspec:PTR BYTE
 
        LoadPtr ds, dx, fspec           ; Point DS:DX to file spec
        mov     ax, access              ; AL = access code
        mov     ah, 3Dh                 ; AH = function number
        int     21h                     ; Open file
        jnc     exit                    ; If ok, return AX = handle
        mov     ax, -1                  ; Else set error code
exit:   ret
 
OpenFile ENDP
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