Question

I am working on an assignment for a college assembly class. We are using IBM Mainframe PC370 emulator. (Old school, but great starting point)

I always try to go a little beyond the scope of the assignment in order to better my programming skills.

What I am trying to do is to move some character data (WORD) into (CWORD) with a offset of 1 using a register. My hope is to be able to place data into an index based off of the input from a file to determine the placement in an index.

We have been given a file that has a five digit dollar figure in position 1-5 and a two digit month code in position 20-21. I would like to put the month code in a register to determine the offset to add the dollar amount into that position in the index.

The following code is what I have been using to attempt the register offset.

Is this even possible? I have not found anything in the textbook or online that specifically discusses doing this type of thing.

         L     R5,1
         MVC   CWORD+0(R5),WORD
         WTO   CWORD
         WTOR  'PRESS ENTER TO EXIT',EXIT

Thank you for your time.
SUBCAN

Answer 1

You wrote:

      L     R5,1                        Get the fullword (32bit) value at location 0001.
      MVC   CWORD+0(R5),WORD            Copy the 5 bytes at location WORD to location CWORD.
      WTO   CWORD                       Display the contents of CWORD.
      WTOR  'PRESS ENTER TO EXIT',EXIT  Display the message and wait for a response.

Plus, presumably:

CWORD DS    CL5                     Output area.
      ...
WORD  DS    CL4                     Input area

You should have written:

      LA    R5,CWORD+1                  Get the address of the second byte of CWORD.
      MVC   0(L'WORD,R5),WORD           Copy the Length(WORD) bytes at location WORD to location CWORD+1.
      WTO   CWORD                       Display the contents of CWORD.
      WTOR  'PRESS ENTER TO EXIT',EXIT  Display the message and wait for a response.
      ...
CWORD DS    CL5                     Output area.
WORD  DS    CL4                     Input area

At least, that sounds like what you wanted. But it isn’t 100% clear from your question. If that wasn’t your intention.