Operation Codes and Extenders

Definition:

Opcode extenders in IBM i are like modifiers for commands in programming. They help you specify details or customize the behavior of an operation, making it more flexible and tailored to your specific needs in the program you’re writing.

Types of Opcode extenders

Uses of Opcode extenders

• For Assigning values.
• For Arithmetic operations.
• For Strings operations.
• For date/time/timestamp operations.
• For File operations

Opcodes extenders for Assigning values.

We have opcode extenders that are used while assigning numeric and string values. Below are the definitions of the work variables that we are using to perform operations using opcode.

• Eval(H): Half adjust (round) of the numeric value while evaluating a variable or parameter.
  

  

  At line 31, once the eval opcode executes, it will add the values of a and b (i.e., 10.25 and 10.20) and assign a 20.45 value to the Result2 variable.
  At line 34, once the eval opcode executes, it will add the values of a and b (i.e., 10.25 and 10.20) and assign a 20.4 value to the Result3 variable as it has only one decimal.
  At line 37, once the eval opcode executes with Half Extender, it will add the values of a and b (i.e., 10.25 and 10.20) and assign a 20.5 value to the Result variable by rounding the value from 20.45 to 20.5.

• Move(P) & Movel(P): Pad the string value with blank while moving from one variable to another.
  

  

  At line 41, once the move opcode executes, it will move the value from A1 (‘AAAAA’) to B2(‘BBBBBBBBBB’) and assign the ‘BBBBBAAAAA’ value to the B2 variable.
  At line 45, once the move opcode with P extender executes, it will move the value from A1 (‘AAAAA’) to B2(‘BBBBBBBBBB’) and assign the ‘ AAAAA’ value to the B2 variable.
  At line 49, once the Movel opcode executes, it will move the value from A1 (‘AAAAA’) to B2(‘BBBBBBBBBB’) and assign the ‘AAAAABBBBB’ value to the B2 variable.
  At line 53, once the Movel opcode with P extenders executes, it will move the value from A1 (‘AAAAA’) to B2(‘BBBBBBBBBB’) and assign the ‘AAAAA ’ value to the B2 variable.

• Eval(M): It evaluates the default decimal value in a variable.
  

  

  At line 57, once the Eval opcode with M extender executes, it will evaluate the value 2.80000 to the Result4.

• Eval(R): It evaluates the result decimal position precision value in a variable.
  

  

  At line 57, once the Eval opcode with R extender executes, it will evaluate the value 2.85714 to the Result4.

Opcodes extenders for Arithmetic operations.

We have opcode extenders that are used while performing arithmetic operations. Below are the definitions of the work variables that we are using to perform operations using opcode.

• Add(H): Half adjust (round) of the numeric value while adding the values of the variables.
  

  

  At line 64, once the Add opcode executes, it will add the values of a and b (i.e., 10.25 and 10.20) and assign a 20.45 value to the Result2 variable.

  At line 66, once the Add opcode executes with Half Extender, it will add the values of a and b (i.e., 10.25 and 10.20) and assign a 20.5 value to the Result variable by rounding the value from 20.45 to 20.5.

• Z-Add(H): Half adjust (round) of the numeric value while adding zero to factor 2.
  

  

  At line 72, once the Z-Add opcode executes with Half Extender, it will add the value of b and Result (i.e., 10.20 and 0) and assign a 10.2 value to the Result variable by rounding the value from 10.20 to 10.2.

  Note: Result value will automatically change from 50 to zero as per Z-ADD opcode, it will convert the Result value to zero and then add with factor-2.

  0 + Factor 2 (numeric)  Result field

• Sub(H): Half adjust (round) of the numeric value while subtracting the values from one variable to another.
  

  

  At line 78, once the Sub opcode executes, it will subtract the value from e to f (i.e., 20.55 and 10.20) and assign a 10.35 value to the Result2 variable.

  At line 82, once the Sub opcode executes with Half extender, it will subtract the value from e to f (i.e., 20.55 and 10.20) and assign a 10.4 value to the Result variable by rounding the value from 10.35 to 10.4.

• Z-Sub(H): Half adjust (round) of the numeric value while subtracting factor-2 from 0.
  

  

  At line 88, once the Z-Sub opcode executes with Half extender, it will subtract the value from Result to b (i.e., 0 and 10.20) and assign –10.2 value to the Result variable by rounding off the value from 10.20 to 10.2.

  Note: Result value will automatically change from 50 to zero as per Z-SUB opcode, it will convert the Result value to zero and then subtract it to factor-2.

  0 – Factor 2 (numeric)  – Result field

• MULT(H): Half adjust (round) of the numeric value while multiplying the value of variables.
  

  

  At line 93, once the Mult opcode executes, it will multiply the value of a and b (i.e., 10.25 and 10.20) and assign a 104.55 value to the Result2 variable.

  At line 96, once the Mult opcode executes with Half extender, it will multiply the value of a and b (i.e., 10.25 and 10.20) and assign 104.6 value to the Result variable by rounding the value from 104.55 to 104.6.

• DUMP(A): It is used to perform the dump operation to ensure the operation occurs regardless of the debug option set in the H specification.
  

  

  At line 44, once the Eval opcode executes, it will try to divide the Num1 by Num2 (i.e., 100 and 0) and assign the default value 1 to Result as 100/0 is not possible.

Opcodes extenders for Strings operations.

We have opcode extenders that are used while performing string operations. Below are the definitions of the work variables that we are using to perform operations using opcode.

• SUBST(E P): Error handling or padding with blank while substring the string variable.
  

  

  At line 35, once the Subst opcode executes, it will substring the variable Target (‘XXXXXXXX’) with String1 (‘TEST123’) from starting position T (5) till length (3) and substring the value of target from ‘XXXXXXXX’ to ‘T12XXXXX’.

  At line 37, once the Subst opcode with E extender executes, it will try to substring the variable Target (‘XXXXXXXX’) with String1 (‘TEST123’) from starting position X (22) till length (3) but display the ‘Error’ message as the 22 index is not present in Target variable.

  At line 43, once the Subst opcode with P extender executes, it will substring the variable Target (‘XXXXXXXX’) with String1 (‘TEST123’) from starting position T (5) till length (3) and substring the value of target from ‘XXXXXXXX’ to ‘T12 ’.

• SCAN(E): Error handling while searching the string.
  

  

  At line 46, once the Scan opcode executes, it will try to search the blank in the variable String (‘Search String’) from starting position K (5) and 7 will assign it to the Pos variable.

  At line 46, once the Scan opcode with E extender executes, it will try to search the blank in the variable String (‘Search String’) from starting position X (22) but display the ‘Error’ message as the 22 index is not present in a String variable.

• XLATE(E P): Error handling or padding with blank while translating from character to character by the protocol specified in factor-1.
  

  

  At line 55, once the Xlate opcode executes, it will try to translate the Chgcase2 (‘rpg dept’) variable with Result2 (‘XXXXXXXXXXXXXXX’) by the protocol specified in factor-1 and assign the new value ‘RPG DEPT XXXXX‘ to the Result2.

  At line 60, once the Xlate opcode with P extender executes, it will try to translate the Chgcase2 (‘rpg dept’) variable with Result2 (‘XXXXXXXXXXXXXXX’) by the protocol specified in factor-1 and assign the new value ‘RPG DEPT ‘ to the Result2 while padding the ‘XXXXX’ with blank of Result2.

  At line 68, once the Xlate opcode with E extender executes, it will try to translate the Chgcase2 (‘rpg dept’) variable with Result2 (‘XXXXXXXXXXXXXXX’) from starting position X (22) by the protocol specified in factor-1 but display the ‘Error’ message as the 22 index is not present in Chgcase2 variable.

• CHECK(E): Error handling while checking the non-occurrence of a character in a string.
  

  

  At line 73, once the Check opcode executes, it will try to check the factor-1 (‘ABCD) in the factor-2 variable Substring (‘AABC1ABD2AV3A’) and 5 will assign it to the Pos variable.

  At line 76, once the Check opcode executes, it will try to check the factor-1 (‘ABCD) in factor-2 variable Substring (‘AABC1ABD2AV3A’) from starting position T (5) and 20 will assign to Pos variable.

  At line 78, once the Check opcode with E extender executes, it will try to check the factor-1 (‘ABCD) in factor-2 variable Substring (‘AABC1ABD2AV3A’) from starting position X (22) but display the ‘Error’ message as the 22 index is not present in substring variable.

Opcodes extenders for date/time/timestamp operations.

We have opcode extenders that are used while performing date/time/timestamp operations. Below are the definitions of the work variables that we are using to perform operations using opcode.

• Test(EDTZ): Validate the date, time or timestamp.
  

  

  

  At line 29, once the Test opcode with Z extender executes, it will try to test the timestamp Char_Tstmp (‘19960723140856834000’) with *ISO format and turn off the error indicator 18 as the Char_Tstmp1 is the correct timestamp.

  At line 30, once the Test opcode with Z extender executes, it will try to test the timestamp Char_Tstmp1 (‘190723140856834000’) with *ISO format and turn on the error indicator 18 as the Char_Tstmp1 is not the correct timestamp.

  At line 31, once the Test opcode with Z and E extender executes, it will try to test the timestamp Char_Tstmp1 (‘190723140856834000’) with *ISO format and display the message ‘Invalid Fmt’ as the Char_Tstmp1 is not correct timestamp.

  At line 36, once the Test opcode with D extender executes, it will try to test the date Char_Date (‘041596’) with *MDY format and turn off the error indicator 19 as the Char_Date is the correct date.

  At line 37, once the Test opcode with D and E extender executes, it will try to test the date Num_Date (‘910921’) with *DMY format and display the message ‘Invalid Fmt’ as the Num_Date is in YYMMDD format, but we are checking in*DMY format.

  At line 41, once the Test opcode with E and T extender executes, it will try to test the time Char_Time (‘13:05 PM’) with *USA format and it won’t give any error as the format of Char_Time matches with the *USA format.

Opcodes extenders for file operations.

We have an ‘N’ opcode extender that is used to make the record not locked while reading. Before is the simple example of an N opcode extender.

On line 9, we have declared one file PIOFILE in update mode, and on line number 10, we are reading the same file 10 times from 1 to 10. Once line 21 executes with the N opcode extender, the record is not locked while reading operation and if any update/delete operation is performed then it will execute without any error.