> -----Original Message-----
> From: IBM Mainframe Discussion List
> [mailto:[email protected]] On Behalf Of Monika Amiss
> Sent: Tuesday, March 29, 2011 12:07 PM
> To: [email protected]
> Subject: binary add
>
> Dear group,
>
> I'm reading some SMF30 records and want to accumulate
> several 4 byte binary values (like CPU SU, IO SU, ...) for
> jobs which achieve the same criteria. But the summation grows
> over the 4 byte capacity (I use AR in Amode31). Is there a
> way to use 2 register for the summation. Or can I use
> Amode64-Code only for the addition. I fear to consume to much
> resources if I convert the data to decimal each time.
>
> Hope somebody could help me. Any hint appreciated.
> With best regards
> Monika
If you are on a z, you can use 64 bit arithmetic. It has nothing to do with
AMODE. You can use 64 bit arithmetic even in 24 or 31 bit addressing mode. Eg.
Instead of:
L R2,FULLWORD1
A R2,FULLWORD2
ST R2,RESULT
you could do:
LGF R2,FULLWORD1 LOAD 64 BIT R2 FROM 32 BIT FULLWORD1
AGF R2,FULLWORD2 ADD 32 BIT FULLWORD2 TO 64 BIT R2
STG R2,DOUBLEWORD SAVE 64 BIT RESULT
or
LGF R2,FULLWORD1 LOAD 32 BIT FULLWORD INTO 64 BIT R2 WITH SIGN
EXTENTION
LGF R3,FULLWORD2 SAME WITH R3
AGR R2,R3 ADD TWO 64 BIT REGISTERS
note. Do __NOT__ do:
L R2,FULLWORD1
L R3,FULLWORD2
AGR R2,R3
In the above, the L to load loads only 32 bits and does not clear or sign
extend the high order fullword of the registers. So that the AGR adds the 64
bit registers with the "left over" contents in the high words of R2 and R3. If
you have a 32 bit value in a register, use the LGFR instruction to "sign
extend" that value into the high word before doing 64 bit arithmetic. You can
even LGFR Rx,Rx to sign extend a value into the same register. Also keep in
mind that all GP registers on a z are 64 bits in size. It's just that some
instructions do not disturb the high (or sometimes the low) fullword bits.
In the past, on non-z equipment, I have done 64 bit arithmetic.
L R2,FULLWORD1
SRDA R2,32 64 BIT VALUE IN R2/R3
L R4,FULLWORD2
SRDA R4,32 64 BIT VALUE IN R4/R5
ALR R4,R2 ADD HIGH WORD
ALR R5,R3 ADD LOW WORD
BNO AROUND NO OVERFLOW (CARRY)
AL R4,=F'1' LOW WORD OVERFLOW - CARRY
AROUND DS 0H
--
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IT
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