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;* FindFirst - Finds first entry in given directory matching specification.
;*
;* Shows:   DOS Function - 4Eh (Find First File)
;*          Keywords - USES
;*          Instructions - ret     pushf    popf
;*
;* Params:  attr - Attribute code (see header comments for CreateFile)
;*          fspec - Pointer to ASCIIZ file specification
;*          finfo - Pointer to 43-byte buffer to receive
;*                  data from matched entry
;*
;* Return:  Short integer with error code
;*          0 if successful
;*          1 if no match found
 
        .DATA
old_dta DD      WORD PTR ?              ; Storage for old DTA address
 
        .CODE
 
FindFirst PROC \
        USES ds, \
        attr:WORD, fspec:PTR BYTE, finfo:PTR BYTE
 
        push    ds                      ; Pass far pointer
        mov     ax, OFFSET @data:old_dta;   to old_dta
        push    ax
        call    GetDTA                  ; Get current DTA address
        add     sp, 4                   ; Adjust stack
 
        mov     cx, attr                ; Load CX with file attribute
        LoadPtr ds, dx, finfo           ; DS:DX points to 43-byte buffer
        push    ds                      ; Make this new DTA
        push    dx
        call    SetDTA                  ; Set 43-byte buffer as DTA
        add     sp, 4                   ; Adjust stack
        LoadPtr ds, dx, fspec           ; Point DS:DX to file spec
        mov     ah, 4Eh                 ; AH = function number
        int     21h                     ; Find First File
 
        pushf                           ; Preserve flags
        push    WORD PTR @data:old_dta[2] ; Pass far pointer to
        push    WORD PTR @data:old_dta[0] ;   SetDTA procedure
        call    SetDTA                  ; Restore DTA address to orig
        sub     ax, ax                  ; Set error code
        add     sp, 4                   ; Adjust stack
        popf                            ; Recover flags
        jnc     exit                    ; Exit if successful match
        inc     ax                      ; Else set error code to 1
exit:   ret
 
FindFirst ENDP
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