Querries Regarding MVS Assembler

Comments

• Unknown

  September 1999

  THe odds are that the value in TDATUM
  
  will be packed decimal with the last (rightmost)
  
  nibble being the hex value "C". When it got
  
  unpacked, the last byte became X"C-",
  
  and you need it to be X"F-" so it can be
  
  standard ebcdec. You could have used
  
  OI, but the MVZ accomplishes the same thing,
  
  it puts the zone part to be F instead of C.
  
  Jerry Burnett [email protected]
  
  : Hello HI
  
  : I have a MVS Assembly code which is to be Impact Analysis for year 2000

  
  : From this code i can only understand that the TDATUM variable which consists a
  
  : date is been unpacked and then formatted in DD.MM.YY in variable MAEN

  
  : I am not able to understand the last instruction MVZ What it is doing what will
  
  : the value in variable MAEN after this operation.

  
  : UNPK DATE,TDATUM
  
  : MVC MAEN(2),DATE
  
  : MVI MAEN+2,C'.'
  
  : MVC MAEN+3(2),DATE+2
  
  : MVI MAEN+5,C'.'
  
  : MVC MAEN+6(2),DATE+4
  
  : MVZ MAEN+7(1),=X'FF'

  
  :
  
  : Please Look into it ASAP the answer for this will be greately appreciated
  
  : Waiting for your reply

  
  : Regards
  
  : Vijay

  
  
  
  
  
• Unknown

  September 1999

  
  
  The last (rightmost) nibble of the contents
  
  of TDATUM is most likely a hexidecimal "C"
  
  (signifying a plus sign), and this code is
  
  attempting to prepare the date contents
  
  for printing, or viewing, and needs it to be
  
  in standard EDCDIC, so the "C" has to changed
  
  to "F". After unpacking, the "C" was switched
  
  with whatever digit came before it (the final
  
  numeric digit in the TDATUM field), and the
  
  MVZ instruction changes the "C" to "F".
  
  The MVZ only moves the leftmost nibble,
  
  which is a "C" after unpacking. I have seen
  
  this accomplished most often with the
  
  OI MAEN+7,x'F0' instruction (which avoids
  
  a double reference to memory), but the
  
  MVZ used here accomplishes the same thing.
  
  Jerry Burnett [email protected]

  
  : Hello HI
  
  : I have a MVS Assembly code which is to be Impact Analysis for year 2000

  
  : From this code i can only understand that the TDATUM variable which consists a
  
  : date is been unpacked and then formatted in DD.MM.YY in variable MAEN

  
  : I am not able to understand the last instruction MVZ What it is doing what will
  
  : the value in variable MAEN after this operation.

  
  : UNPK DATE,TDATUM
  
  : MVC MAEN(2),DATE
  
  : MVI MAEN+2,C'.'
  
  : MVC MAEN+3(2),DATE+2
  
  : MVI MAEN+5,C'.'
  
  : MVC MAEN+6(2),DATE+4
  
  : MVZ MAEN+7(1),=X'FF'

  
  :
  
  : Please Look into it ASAP the answer for this will be greately appreciated
  
  : Waiting for your reply

  
  : Regards
  
  : Vijay

  
  
  
  
  
  
  
• Unknown

  November 1999

  : Hello HI
  
  : I have a MVS Assembly code which is to be Impact Analysis for year 2000

  
  : From this code i can only understand that the TDATUM variable which consists a
  
  : date is been unpacked and then formatted in DD.MM.YY in variable MAEN

  
  : I am not able to understand the last instruction MVZ What it is doing what will
  
  : the value in variable MAEN after this operation.

  
  : UNPK DATE,TDATUM
  
  : MVC MAEN(2),DATE
  
  : MVI MAEN+2,C'.'
  
  : MVC MAEN+3(2),DATE+2
  
  : MVI MAEN+5,C'.'
  
  : MVC MAEN+6(2),DATE+4
  
  : MVZ MAEN+7(1),=X'FF'

  
  :
  
  : Please Look into it ASAP the answer for this will be greately appreciated
  
  : Waiting for your reply

  
  : Regards
  
  : Vijay