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page 80,132
title CP/DOS DosClose mapper * * *
dosxxx segment byte public 'dos'
assume cs:dosxxx,ds:nothing,es:nothing,ss:nothing
;
; ************************************************************************* *
; *
; * MODULE: DosClose
; *
; * FUNCTION: This module will close a file or a device.
; *
; * CALLING SEQUENCE:
; *
; * PUSH WORD FileHandle ; File Handle or device handle
; * CALL DosClose
; *
; * RETURN SEQUENCE:
; *
; * IF ERROR (AX not = 0)
; *
; * AX = Error Code:
; *
; * o Invalid file handle
; *
; *
; * MODULES CALLED: DOS int 21H function 3EH
; *
; *
; *************************************************************************
public DosClose
.sall
.xlist
include macros.inc
.list
str struc
old_bp dw ?
return dd ?
FileHandle dw ? ; file or device handle
str ends
DosClose proc far
Enter DosClose ; push registers
; Only files are closed. Devices are not closed, since OPEN creates
; a dummy device handle without actually openning the device.
mov bx,[bp].FileHandle ; load the handle
mov ax,bx ; check for device handle
neg ax ; if device handle, return
jns GoodExit ; do not close the device
FileCloseRequest:
mov ax,03e00h ; load opcode
int 21h ; close the file
jc ErrorExit ; return if error
GoodExit:
sub ax,ax ; else, set good return code
ErrorExit:
mexit ; pop registers
ret size str - 6 ; return
DosClose endp
dosxxx ends
end
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