CPY - CoPY register contents

Remark 1:
This document is intended for evaluation of the setup for documentation.
Please e-mail us any comments you may have.

Remark 2:
The final version of this document will also describe all other features of the CPY macro: storage-to-register, register-to-storage, storage-to-storage and type checking.

Remark 3:
View the complete list of defined field types .

This document contains the following chapters:

• 1 CPY - copy register contents
  • 1.0 Description
  • 1.1 Environment
  • 1.2 Programming Requirements
  • 1.3 Restrictions
  • 1.4 Input Register Information
  • 1.5 Output Register Information
  • 1.6 Performance Implications
  • 1.7 Syntax
  • 1.8 Parameters
  • 1.9 Abend Codes
  • 1.10 Return and Reason Codes
  • 1.11 Examples
• 2 Miscellaneous
  • 2.1 Wish List
  • 2.2 Maintenance status
  • 2.3 Source Code

1.0 Description

The CPY macro will copy the contents of a register unchanged to another register as follows:

• If source and destination are both general purpose registers a LR instruction is generated.
• If source and destination are both access registers a CPYA instruction is generated.
• If the source is a general purpose register and the destination is an access register a SAR instruction is generated.
• If the source is an access register and the destination is a general purpose register an EAR instruction is generated.
• If source and destination are both floating point registers a LER instruction is generated.
• All other combinations of registers are flagged as errors.

If the source and destination register are the same, the operation is discarded (i.e. no code is generated) and, unless suppressed by the NOWARN option, a warning is issued.

1.1 Environment

1.2 Programming Requirements

The registers must have a type code of 'g' for general purpose registers, 'a' for access registers, or 'f' for floating point registers. The preferred way to achieve this is to start your program with the PGM macro, or to define all registers by invoking the MAPREGS macro. EQUating a symbol to one of the MAPREGS-defined registers using the EQU macro also has the desired effect.

1.3 Restrictions

The CPY macro does not support:

• copying to or from control registers
• copying between floating point and general purpose (fixed point) registers
• copying to or from special registers (e.g. PSW, prefix, floating point status, etc)

The CPY macro always generates reenterable and refreshable code. List and execute forms for the CPY macro are not supported.

1.4 Input Register Information

Before issuing the CPY macro, the caller does not have to place any information into any register unless using it as a source for the CPY operation.

1.5 Output Register Information

When control returns to the caller, the general purpose registers (GPRs) are unchanged, except when a general purpose register is specified as the target of the CPY operation.

When control returns to the caller, the access registers (ARs) are unchanged, except when an access register is specified as the target of the CPY operation.

1.6 Performance Implications

None.

1.7 Syntax

The CPY macro is written as follows:

1.8 Parameters

The parameters are explained as follows:

destination

The destination register for the copy operation. May be any of the general purpose, access, or floating point registers.

,source

The source register for the copy operation. May be any of the general purpose, access, or floating point registers.

,NOWARN

When an operation is suppressed, due to destination and source registers being the same, a warning message is issued, unless the NOWARN option has been specified. If specified, the warning message is suppressed; the operation, however, is discarded irrespective of the NOWARN parameter.

1.9 Abend Codes

None.

1.10 Return and Reason Codes

None.

1.11 Examples

Some CPY examples are:

         MAPREGS ,                      * Define all registers
RDCB     EQU   R2                       * Define ptr to DCB
ARDCB    EQU   AR2                      * and ALET for DCB

SAMP1    CPY   R1,AR5                   * Copy ALET from AR5 to GPR1

SAMP2    CPY   R2,R1                    * Copy value from GPR1 to GPR2

SAMP3    CPY   R2,RDCB                  * Copy DCB pointer?
+*MNOTE 4,'Copy to self not useful: ignored'

SAMP4    CPY   R2,RDCB,NOWARN           * Equally useless, without
  warning

2 Miscellaneous

2.1 Wish List

• For oversized packed fields unpacking may be done by processing left to right in clusters of several bytes at a time
• For oversized zoned fields packing may be done by processing right to left in a loop.
• For every EQUREG a check must be made whether the source and/or destination registers are in USE. Change EQUREG with a NO=(...) keyword.
• Add logic for 64-bit registers and associated new field types

2.2 Maintenance Status

Currently not in maintenance

2.3 Source Code

Source code of macro CPY is available for reference only.
Any other use is licensed under the GPL.
For other licenses, please e-mail us.

Please e-mail us with your comments. Thanks in advance.

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