GN_Prs, Parse filename

Register parameters

RST 20H, DEFW $5809

IN:
     HL = 0,1,2; not allowed (B=0)
     BHL = points to filename
     (B = 0 is interpreted as local pointer)
     Filename must be terminated by a control character.
OUT, if call successful:
     Fc = 0
     A0 = 1, extension used
     A1 = 1, filename used
     A2 = 1, explicit directory used
     A3 = 1, current directory (".") used
     A4 = 1, parent directory ("..") used
     A5 = 1, wildcard directory ("//") used
     A6 = 1, device specified
     A7 = 1, wildcards used

     B = number of segments in filename
     C = length of filename including terminator

OUT, if call failed:
     Fc = 1
     A = error code:
          RC_IVF ($17), poor syntax

Registers changed after return:
     ....DEHL/IXIY same
     AFBC..../.... different

Related calls

GN_Esa, read & write to filename segments
GN_Fcm, compress a filename
GN_Fex, expand a filename
GN_Opw, Open wildcard handler
GN_Pfs, parse filename segment
GN_Wcl, close wildcard handle
GN_Wfn, fetch next match for wildcard string (handle)
GN_Wsm, match filename segment to wildcard string