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func-code
MFDSP$–Master File Directory Service Package
The function code may be given as an actual number, a tag that has been equated to
an actual number, or the address of a word that contains the number. The first time
the MFDSP$ routine is called, it must be called with a function code of zero or one.
If the MFD file was created using the DGET$ function on the ER MSCON$, then use
zero on the MFDSP$ call. If the MFD file was created using the DGET$P function on
the ER MSCON$, then a function code of one must be used on the MFDSP$ call.
If this parameter is omitted, the routine uses the value in H2 of register A1 as the
function code. If device-table-size is specified as the fourth parameter then this
parameter is required.
The function codes for MFDSP$ are the following:
0 Initialize for DGET$ file and return the address of the first lead item.
1 Initialize for DGETP$ file and return the address of the first main item.
2 Get next lead item (DGET$ file only).
3 Get sector 1 of lead item (DGET$ file only).
4 Get next main item.
5 Get next sector of main item.
6 Get first DAD table associated with the main item returned by function 4 or 5.
7 Get next DAD table.
8 Find item whose MFD address is in A2.
9 Convert MFD address in A2 to DGET$ file relative address in A3.
10 Get a ER MSCON$ (DGET$) copy of the MFD and initialize (function code 0)
device-table-size
If this parameter is omitted, the default maximum size of the device number table is
1,000 words. The device table is a buffer built by MFDSP$ to contain a 1-word entry
for each mass storage device configured on the system. Entries are located in the
table according to the device number or LDAT index (see the Exec System Software
Administration Reference Manual (subsection 2.2) for more information on the LDAT
index). This means that if a device is numbered 100, its entry will occupy the 101 st
word of the table (entries begin at the second word of the table). If this parameter is
included, the ‘func-code’ parameter must also be included.
The default maximum size of the device number table is 1,000 words. If your system
includes devices numbered greater than 999, you can use this parameter to increase
the table size to a maximum of 4,096 words. The requested word size of the table
should be at least the highest device number plus 1. A device-table-size value of
1000 or less will use the current table size of 1,000 words. The pkt-length
(parameter 1) should also be increased when a larger device table size is requested
by the fourth parameter. The device table size parameter is only used by functions
that initialize the device table (functions 0, 1, and 10.) The value of this parameter is
passed in H1 of register A1.
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