Roll Down (QsnRollDown) API

Required Parameter Group:

1	Number of lines to roll	Input	Binary(4)
2	Top row of roll area	Input	Binary(4)
3	Bottom row of roll area	Input	Binary(4)

Omissible Parameter Group:

4	Command buffer handle	Input	Binary(4)
5	Low-level environment handle	Input	Binary(4)
6	Error code	I/O	Char(*)

Returned Value:

Return code

Output

Binary(4)

  Default Public Authority: *USE

  Service Program: QSNAPI

  Threadsafe: No

The Roll Down (QsnRollDown) API rolls the screen down a given number of lines within the roll area specified. The following conditions cause a CPFA315 error to occur:

A top row of zero
A bottom row greater than the number of display lines
A top row greater than or equal to the bottom row
A roll area greater than the bottom row minus the top row

This API corresponds directly to the 5250 Roll command. See the 5250 data stream documentation for details.

Restrictions

The following considerations apply to the QsnRollDown API:

Lines vacated due to a roll are not cleared to nulls.
The command does not change the format table, and so, should be avoided when it could produce discrepancies between the format table and the display.
Data rolled out of the roll area are lost.

Authorities and Locks

None

Required Parameter Group

Number of lines to roll: INPUT; BINARY(4)
The number of lines to roll the designated area down by.
Top row of roll area: INPUT; BINARY(4)
The line number defining the top line of the area that will participate in the roll.
Bottom row of roll area: INPUT; BINARY(4)
The line number defining the bottom line of the area that will participate in the roll.

Omissible Parameter Group

Command buffer handle: INPUT; BINARY(4)
If this parameter is omitted or specified as 0, this is a direct operation and the screen is rolled down immediately. Otherwise, this is an indirect operation and the command is stored in the command buffer without an I/O operation taking place.
Low-level environment handle: INPUT; BINARY(4)
The low-level environment that the operation applies to. If this parameter is omitted or given with a value of zero, the default low-level environment is used.
Error code: I/O; CHAR(*)
The structure in which to return error information. For the format of the structure, see Error Code Parameter. If this parameter is omitted, diagnostic and escape messages are issued to the application.

Returned Value

Return code: OUTPUT; BINARY(4)
A return code indicating the result of the operation. The value returned will be 0 if the operation was successful, or -1 otherwise.

Error Messages

Message ID	Error Message Text
CPF24B4 E	Severe error while addressing parameter list.
CPF3CF1 E	Error code parameter not valid.
CPF3CF2 E	Error(s) occurred during running of &1 API.
CPFA301 E	Command buffer is full.
CPFA303 E	Error occurred for screen I/O operation.
CPFA304 E	Data-stream error &1 reported for screen I/O operation.
CPFA305 E	Cannot add operation to command buffer.
CPFA315 E	Roll parameters not valid.
CPFA31E E	Required parameter &1 omitted.
CPFA331 E	Buffer handle incorrect.
CPFA334 E	Low level environment handle incorrect.
CPFA343 E	Output operation not done.
CPFA344 E	The file &2 in library &3 is not valid.
CPFA345 E	The invite active flag is not valid.

API introduced: V2R3

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