OPSYN instruction

The OPSYN instruction defines or deletes symbolic operation codes.

The OPSYN instruction has two formats. The first format defines a new operation code to represent an existing operation code, or to redefine an existing operation code for:

Machine and extended mnemonic branch instructions
Assembler instructions, including conditional assembly instructions
Macro instructions


Define operation code

>>-+-symbol-----------+--OPSYN--operation_code_2---------------><
   '-operation_code_1-'

If operation_code_2 has been previously defined as both a machine instruction and as a macro, both are copied to the definition of operation_code_1.

The second format deletes an existing operation code for:

Machine and extended mnemonic branch instructions
Assembler instructions, including conditional assembly instructions
Macro instructions


Delete operation code

>>-operation_code_1--OPSYN-------------------------------------><

symbol

Is one of the following:

An ordinary symbol that is not the same as an existing operation code
A variable symbol that has been assigned a character string with a value that is valid for an ordinary symbol and is not the same as an existing operation code

operation_code_1

Is one of the following:

An operation code described in this chapter, or any machine instruction (such as those described in Machine instruction statements), or How to write conditional assembly instructions
The operation code defined by a previous OPSYN instruction
The name of a previously defined macro.

operation_code_2

Is one of these:

An operation code described in this chapter, or any machine instruction (such as those described in Machine instruction statements), or How to write conditional assembly instructions
The operation code defined by a previous OPSYN instruction
The name of a previously defined macro.

In the first format, the OPSYN instruction assigns the properties of the operation code denoted by operation_code_2 to the ordinary symbol denoted by symbol or the operation code denoted by operation_code_1.

In the second format, the OPSYN instruction causes the operation code specified in operation_code_1 to lose its properties as an operation code.

The OPSYN instruction can be coded anywhere in the program to redefine an operation code, following an ICTL instruction, if any.

The symbol in the name field can represent a valid operation code. It loses its current properties as if it had been defined in an OPSYN instruction with a space-filled operand field. In the following example, L and LR both possess the properties of the LR machine instruction operation code:

L        OPSYN           LR

When the same symbol appears in the name field of two OPSYN instructions, the latest definition takes precedence. In this example, STORE now represents the STH machine operation:

STORE    OPSYN           ST
STORE    OPSYN           STH

Note: OPSYN is not processed during lookahead mode (see Lookahead). Therefore it cannot be used during lookahead to replace an opcode that must be processed during lookahead, such as COPY. For example, assuming AFTER is defined in COPYBOOK, the following code gives an ASMA042E error (Length attribute of symbol is unavailable):

          AIF  (L'AFTER LT 2).BEYOND
 OPCOPY   OPSYN COPY               OPSYN not processed during look ahead
          OPCOPY COPYBOOK          OPCOPY fails
 .BEYOND ANOP ,