These are the requirements for the caller:

The caller must include the IHAPSA mapping macro and must be enabled for DAT.

None.

Before issuing the DATOFF macro, the caller does not have to place any information into any register unless using it in register notation for a particular parameter, or using it as a base register.

None.

The DATOFF macro is written as follows:

The parameters are explained as follows:

index

Specifies the function that is to be given control in the DAT-OFF section of the nucleus. The possible values for index, along with the associated functions, are as follows:

Index

Function

INDCDS

31-bit DAT-OFF compare double and swap

INDMVCL0

31-bit general DAT-OFF move character long

INDMVCLK

31-bit general DAT-OFF move character long in user key

INDXC0

31-bit general DAT-OFF exclusive OR character

INDCDS64

64-bit DAT-OFF compare double and swap

INDMVCL64

64-bit general DAT-OFF move character long

INDMVCLK64

64-bit general DAT-OFF move character long in user key

INDXC64

64-bit general DAT-OFF exclusive OR character

INDUSR1

User-written 31-bit

INDUSR2

User-written 31-bit

INDUSR3

User-written 31-bit

INDUSR4

User-written 31-bit

INDUSR641

User-written 64-bit

INDUSR642

User-written 64-bit

INDUSR643

User-written 64-bit

INDUSR644

User-written 64-bit

For all system-defined index values (INDCDS, INDMVCL0, INDMVCLK, and INDXC0), the user must supply information in certain registers, as shown in the following lists. All register values for INDCDS, INDMVCL0, INDMVCLK, and INDXC0 must be 31-bit addresses. All register values for INDCDS64, INDMVCL64, INDMVCLK64, and INDXC64 must be 64-bit addresses. Callers must be AMODE=64 to use INDCDS64, INDMVCL64, INDMVCLK64, or INDXC64.

INDCDS and INDCDS64

Registers

Information

2-3

First 64-bit operand in even-odd pair of registers (target data)

4-5

Third 64-bit operand in even-odd pair of registers (source data)

6

Location of second operand, a doubleword in storage (target address)

Note: Register 6 contains a real address. If INCDS is specified, then the low order 32 bits of GPR 6 form the real address operand. If INCDS64 is specified, then all 64 bits of GPR6 form the real address operand.

INDMVCL0 and INDMVCL64

Registers

Information

2

Location into which the characters are to be moved

3

Length of the area into which the characters are to be moved

4

Location of the area from which the characters are to be moved

5

Length of the area from which the characters are to be moved

Note: Registers 2 and 4 contain real addresses.

INDMVCLK and INDMVCLK64

Registers

Information

2

Location into which the characters are to be moved

3

Length of the area into which the characters are to be moved

4

Location of the area from which the characters are to be moved

5

Length of the area from which the characters are to be moved

6

Bits 24-27 contain the PSW key in which the MVCL is to be executed

Note: Registers 2 and 4 contain real addresses.

INDXC0 and INDXC64

Registers

Information

2

Location of the results of exclusive OR character processing

3

Bits 24-31 contain one less than the number of bytes on which the exclusive OR is to be performed

4

Location of the operand on which the exclusive OR is to be performed

Note: Registers 2 and 4 contain real addresses.

There are eight DAT-OFF indexes that users can define. These indexes are INDUSR1, INDUSR2, INDUSR3, INDUSR4, INDUSR641, INDUSR642, INDUSR643, and INDUSR644. User written DAT-OFF functions are restricted as follows:

• The user of the DATOFF macro instruction must be in key 0, supervisor state, and executing with DAT turned on.
• The DAT-OFF function must have the attributes AMODE=31 and RMODE=ANY to use INDUSR1, INDUSR2, INDUSR3, and INDUSR4.
• The DAT-OFF function must have the attributes AMODE=64 and RMODE=ANY to use INDUSR641, INDUSR642, INDUSR643, and INDUSR644.
• The DAT-OFF function must preserve register 0 because register 0 contains the return address of the module that issued the DATOFF macro.
• The DAT-OFF function must use branch instructions to link to other DAT-OFF functions.
• The DAT-OFF function must use BSM 0,14 to return from INDUSR1, INDUSR2, INDUSR3, and INDUSR4.
• The DAT-OFF function must return via BR 14 from INDUSR641, INDUSR642, INDUSR643, and INDUSR644.

Note: See z/OS MVS Programming: Authorized Assembler Services Guide for information about how to insert a user-written function in the nucleus.

,RELATED=value

Specifies information used to document the macro and to relate the service performed to some corresponding service or function. The format of the information specified can be any valid coding values that the user chooses.

0FF

See z/OS MVS System Codes for an explanation and programmer responses for these codes.

When DATOFF macro returns control to your program, GPR 15 contains a return code.

See z/OS MVS Programming: Authorized Assembler Services Guide for examples.