14. FILE_OPENIN

*------------------------------------------------------------------------------
* NAME          FILE_OPENIN
*------------------------------------------------------------------------------
* DEPENDENCY    FILE_OPEN
* PURPOSE       To open a file like 'OPEN_IN #3,filename'
* DESCRIPTION   Opens a file in mode 1 (old shared device) The filename is
*               passed in A0 (a pointer to the name). The current job assumes
*               ownership of the channel. May need a TRAP #4 before calling if
*               the filename is relative A6 when called. (SuperBasic).
* INPUTS :
*               A0.L = Pointer to filename
* OUTPUTS :
*               A0.L = Channel id.
*               D0 = Error code
*               Z flag set if no errors, unset otherwise.
*------------------------------------------------------------------------------
file_openin     movem.l d1-d3,-(a7)     ; Those workers need saving
                moveq   #1,d3           ; Old shared device mode
                bra     fo_params       ; Do the rest via FILE_OPEN