Parameters on entry

The six parameters are:

exit_type

(Input) The address of a fullword of storage that indicates the exit type. The value is always 4, to indicate an ADATA exit.

action

(Input) The address of a fullword integer that can be one of the following three values:

0

OPEN Request. Open and initialize the filter. No ADATA record is available with this call, although there might be initial character string data supplied.

The exit accepts the following return codes:

0: The open action was successful. The exit calls the filter module to inspect and process each ADATA record.
12: The open action was unsuccessful. The filter module is assumed to have closed itself, and is not called again.

1

CLOSE Request. The exit is requesting the filter module to close itself. No ADATA record is available with this call and no further calls are made to the filter module.

The exit accepts the following return codes:

0: The filter module has closed successfully. The exit can delete the filter.
12: The filter module is assumed to have closed itself, and is not called again. The exit can delete the filter.

3

PROCESS Request. A record is available to the filter module for processing. The ADATA record should not be modified.

The exit accepts the following return codes:

0: The filter module has completed its processing of this record, and is ready to accept further records.
12: The filter module is assumed to have closed itself, and is not called again.

return_code

(Output) The address of a fullword integer where the filter module should place a return code. Valid return codes are described under each action.

handle

(Input/Output) The address of a 4-fullword area of storage that is initialized to zero before the OPEN (action=0) call to the filter. Its contents are preserved across subsequent calls. The handle can be used in any way by the filter module; for example, to address working storage for a reenterable filter module.

record_length

(Input) The address of a fullword integer containing the length of the ADATA record. A length is provided for PROCESS (action=3) calls, and for OPEN (action=0) calls when you supply an initial character string.

record

(Input) The address of the ADATA record. This points to the ADATA record for PROCESS (action=3) calls, and to the initial character string for OPEN (action=0) calls.