EP_Prev ($15) - Return previous file entry in File Area

Register parameters

IN:
     A = EP_PREV
   BHL = pointer to current file entry in slot (B=00h-FFh, HL=0000h-3FFFh).

OUT:
   Fc = 0, File Eprom Area available
        Fz = 1, File Entry marked as deleted
        Fz = 0, File Entry is active.
        BHL = pointer to previous file entry in slot (B=00h-FFh, HL=0000h-3FFFh).

   Fc = 1,
        A = RC_Onf
        File Eprom was not found in slot, or current File entry was the first
        File Entry (an attempt was made to go beyond the bottom of the file area)

Registers changed after return:
   A..CDE../IXIY same
   .FB...HL/.... different

Notes

To get the previous file entry, the current file entry pointer must be supplied as argument to this API. The B register defines the absolute bank number which contains the slot mask ($40 for slot 1, $80 for slot 2 and $C0 for slot 3).